marijuana research articles

• Search by keyword
• Search by citation

Page 1 of 5

Factors associated with the use of cannabis for self-medication by adults: data from the French TEMPO cohort study

Medical cannabis, legalized in many countries, remains illegal in France. Despite an experiment in the medical use of cannabis that began in March 2021 in France, little is known about the factors associated w...

• View Full Text

Cannabis use associated with lower mortality among hospitalized Covid-19 patients using the national inpatient sample: an epidemiological study

Prior reports indicate that modulation of the endocannabinoid system (ECS) may have a protective benefit for Covid-19 patients. However, associations between cannabis use (CU) or CU not in remission (active ca...

State licenses for medical marijuana dispensaries: neighborhood-level determinants of applicant quality in Missouri

When state governments impose quotas on commercial marijuana licenses, regulatory commissions use an application process to assess the feasibility of prospective businesses. Decisions on license applications a...

Effect of organic biostimulants on cannabis productivity and soil microbial activity under outdoor conditions

In 2019 and 2020, we investigated the individual and combined effects of two biofertilizers (manure tea and bioinoculant) and one humic acid (HA) product on cannabis biochemical and physiological parameters an...

Neuroimaging studies of cannabidiol and potential neurobiological mechanisms relevant for alcohol use disorders: a systematic review

The underlying neurobiological mechanisms of cannabidiol’s (CBD) management of alcohol use disorder (AUD) remains elusive.

A narrative review of the therapeutic and remedial prospects of cannabidiol with emphasis on neurological and neuropsychiatric disorders

The treatment of diverse diseases using plant-derived products is actively encouraged. In the past few years, cannabidiol (CBD) has emerged as a potent cannabis-derived drug capable of managing various debilit...

Comment on “Hall et al., Topical cannabidiol is well tolerated in individuals with a history of elite physical performance and chronic lower extremity pain”

A national study of clinical discussions about cannabis use among veteran patients prescribed opioids.

The Veterans Health Administration tracks urine drug tests (UDTs) among patients on long-term opioid therapy (LTOT) and recommends discussing the health effects of cannabis use.

Evaluation of dispensaries’ cannabis flowers for accuracy of labeling of cannabinoids content

Cannabis policies have changed drastically over the last few years with many states enacting medical cannabis laws, and some authorizing recreational use; all against federal laws. As a result, cannabis produc...

Oral Cannabis consumption and intraperitoneal THC:CBD dosing results in changes in brain and plasma neurochemicals and endocannabinoids in mice

While the use of orally consumed Cannabis, cannabidiol (CBD) and tetrahydrocannabinol (THC) containing products, i.e. “edibles”, has expanded, the health consequences are still largely unknown. This study examine...

Recent advances in the development of portable technologies and commercial products to detect Δ 9 -tetrahydrocannabinol in biofluids: a systematic review

The primary components driving the current commercial fascination with cannabis products are phytocannabinoids, a diverse group of over 100 lipophilic secondary metabolites derived from the cannabis plant. Alt...

Associations between simultaneous use of alcohol and cannabis and cannabis-related problems in 2014–2016: evidence from the Washington panel survey

To address the research question of how simultaneous users of alcohol and cannabis differ from concurrent users in risk of cannabis use problems after the recreational marijuana legalization in Washington State.

Characteristics of patients with non-cancer pain and long-term prescription opioid use who have used medical versus recreational marijuana

Marijuana use is increasingly common among patients with chronic non-cancer pain (CNCP) and long-term opioid therapy (LTOT). We determined if lifetime recreational and medical marijuana use were associated wit...

Cannabis use, decision making, and perceptions of risk among breastfeeding individuals: the Lactation and Cannabis (LAC) Study

Our primary objective was to understand breastfeeding individuals’ decisions to use cannabis. Specifically, we investigated reasons for cannabis use, experiences with healthcare providers regarding use, and po...

Distribution of legal retail cannabis stores in Canada by neighbourhood deprivation

In legal cannabis markets, the distribution of retail stores has the potential to influence transitions from illegal to legal sources as well as consumer patterns of use. The current study examined the distrib...

Examining attributes of retailers that influence where cannabis is purchased: a discrete choice experiment

With the legalization of cannabis in Canada, consumers are presented with numerous purchase options. Licensed retailers are limited by the Cannabis Act and provincial regulations with respect to offering sales...

Effects of acute cannabis inhalation on reaction time, decision-making, and memory using a tablet-based application

Acute cannabis use has been demonstrated to slow reaction time and affect decision-making and short-term memory. These effects may have utility in identifying impairment associated with recent use. However, th...

Analysis of social media compliance with cannabis advertising regulations: evidence from recreational dispensaries in Illinois 1-year post-legalization

In the USA, an increasing number of states have legalized commercial recreational cannabis markets, allowing a private industry to sell cannabis to those 21 and older at retail locations known as dispensaries....

Comparison of perceptions in Canada and USA regarding cannabis and edibles

Canada took a national approach to recreational cannabis that resulted in official legalization on October 17, 2018. In the United States (US), the approach has been more piecemeal, with individual states pass...

Attitudes of Swiss psychiatrists towards cannabis regulation and medical use in psychiatry: a cross-sectional study

Changes in regulation for cannabis for nonmedical use (CNMU) are underway worldwide. Switzerland amended the law in 2021 allowing pilot trials evaluating regulative models for cannabis production and distribut...

Cannabis and pathologies in dogs and cats: first survey of phytocannabinoid use in veterinary medicine in Argentina

In animals, the endocannabinoid system regulates multiple physiological functions. Like humans, animals respond to preparations containing phytocannabinoids for treating several conditions. In Argentina, laws ...

The holistic effects of medical cannabis compared to opioids on pain experience in Finnish patients with chronic pain

Medical cannabis (MC) is increasingly used for chronic pain, but it is unclear how it aids in pain management. Previous literature suggests that MC could holistically alter the pain experience instead of only ...

The potential for Ghana to become a leader in the African hemp industry

Global interest in hemp cultivation and utilization is on the rise, presenting both challenges and opportunities for African countries. This article focuses on Ghana’s potential to establish a thriving hemp se...

Cannabinoid hyperemesis syndrome presenting with ventricular bigeminy

The is a case of a 28-year-old male presenting to an emergency department (ED) via emergency medical services (EMS) with a chief complaint of “gastritis.” He was noted to have bigeminy on the pre-arrival EMS e...

Driving-related behaviors, attitudes, and perceptions among Australian medical cannabis users: results from the CAMS 20 survey

Road safety is an important concern amidst expanding worldwide access to legal cannabis. The present study reports on the driving-related subsection of the Cannabis as Medicine Survey 2020 (CAMS-20) which surv...

High levels of pesticides found in illicit cannabis inflorescence compared to licensed samples in Canadian study using expanded 327 pesticides multiresidue method

As Cannabis was legalised in Canada for recreational use in 2018 with the implementation of the Cannabis Act , Regulations were put in place to ensure safety and consistency across the cannabis industry. This incl...

Correction: Potency and safety analysis of hemp delta-9 products: the hemp vs. cannabis demarcation problem

The original article was published in Journal of Cannabis Research 2023 5 :29

Cannabis use for exercise recovery in trained individuals: a survey study

Cannabis use, be it either cannabidiol (CBD) use and/or delta-9-tetrahydrocannabinol (THC) use, shows promise to enhance exercise recovery. The present study aimed to determine if individuals are using CBD and...

The COVID-19 pandemic and cannabis use in Canada―a scoping review

Since the start of the COVID-19 pandemic in Canada, the cannabis industry has adapted to public health emergency orders which had direct and indirect consequences on cannabis consumption. The objective of this...

DMSO potentiates the suppressive effect of dronabinol on sleep apnea and REM sleep in rats

Dimethyl sulfoxide (DMSO) is an amphipathic molecule with innate biological activity that also is used to dissolve both polar and nonpolar compounds in preclinical and clinical studies. Recent investigations o...

Potency and safety analysis of hemp delta-9 products: the hemp vs. cannabis demarcation problem

Hemp-derived delta-9 tetrahydrocannabinol (∆ 9 THC) products are freely available for sale across much of the USA, but the federal legislation allowing their sale places only minimal requirements on companies. Pro...

The Correction to this article has been published in Journal of Cannabis Research 2023 5 :33

A comparison of advertised versus actual cannabidiol (CBD) content of oils, aqueous tinctures, e-liquids and drinks purchased in the UK

Cannabidiol (CBD)-containing products are sold widely in consumer stores, but concerns have been raised regarding their quality, with notable discrepancies between advertised and actual CBD content. Informatio...

Cannabis sativa demonstrates anti-hepatocellular carcinoma potentials in animal model: in silico and in vivo studies of the involvement of Akt

Targeting protein kinase B (Akt) and its downstream signaling proteins are promising options in designing novel and potent drug candidates against hepatocellular carcinoma (HCC). The present study explores the...

Conflicting forces in the implementation of medicinal cannabis regulation in Uruguay

Uruguay is widely known as a pioneer country regarding cannabis regulation policies, as it was the first state to regulate the cannabis market for both recreational and medicinal purposes in 2013. However, not...

Why a distinct medical stream is necessary to support patients using cannabis for medical purposes

Since 2001, Canadians have been able to obtain cannabis for medical purposes, initially through the Access to Cannabis for Medical Purposes Regulations (ACMPR). The Cannabis Act (Bill C-45) came into force on ...

Propylene glycol and Kolliphor as solvents for systemic delivery of cannabinoids via intraperitoneal and subcutaneous routes in preclinical studies: a comparative technical note

Substance administration to laboratory animals necessitates careful consideration and planning in order to enhance agent distribution while reducing any harmful effects from the technique. There are numerous m...

No difference in COVID-19 treatment outcomes among current methamphetamine, cannabis and alcohol users

Poor outcomes of COVID-19 have been reported in older males with medical comorbidities including substance use disorder. However, it is unknown whether there is a difference in COVID-19 treatment outcomes betw...

Cannabis for morning sickness: areas for intervention to decrease cannabis consumption during pregnancy

Cannabis use during pregnancy is increasing, with 19–22% of patients testing positive at delivery in Colorado and California. Patients report using cannabis to alleviate their nausea and vomiting, anxiety, and...

The therapeutic potential of purified cannabidiol

The use of cannabidiol (CBD) for therapeutic purposes is receiving considerable attention, with speculation that CBD can be useful in a wide range of conditions. Only one product, a purified form of plant-deri...

Naturalistic examination of the anxiolytic effects of medical cannabis and associated gender and age differences in a Canadian cohort

The aim of the current study was to examine patterns of medical cannabis use in those using it to treat anxiety and to investigate if the anxiolytic effects of cannabis were impacted by gender and/or age.

The Desert Whale: the boom and bust of hemp in Arizona

This paper examines the factors that led to the collapse of hemp grown for cannabidiol (CBD) in Arizona, the United States of America (USA), and particularly in Yuma County, which is a well-established agricul...

Reasonable access: important characteristics and perceived quality of legal and illegal sources of cannabis for medical purposes in Canada

Throughout the past two decades of legal medical cannabis in Canada, individuals have experienced challenges related to accessing legal sources of cannabis for medical purposes. The objective of our study was ...

The reintroduction of hemp in the USA: a content analysis of state and tribal hemp production plans

The reintroduction of Cannabis sativa L . in the form of hemp (< 0.3% THC by dry weight) into the US agricultural sector has been complex and remains confounded by its association with cannabis (> 0.3% THC by dry ...

The Cannabis sativa genetics and therapeutics relationship network: automatically associating cannabis-related genes to therapeutic properties through chemicals from cannabis literature

Understanding the genome of Cannabis sativa holds significant scientific value due to the multi-faceted therapeutic nature of the plant. Links from cannabis gene to therapeutic property are important to establish...

Self-reported adverse events associated with ∆ 8 - Tetrahydrocannabinol (Delta-8-THC) Use

There is an expanding unregulated market for a psychotropic compound called ∆ 8 -Tetrahydrocannabinol (delta-8-THC) that is being derived from hemp, but a summary of adverse events related to delta-8-THC has not be...

The safety of lookalikes: a new THC beverage enhancer and a non-THC counterpart

A new tetrahydrocannabinol (THC) beverage enhancer is available to medical and recreational cannabis consumers across the US. Beverage enhancers that do not contain THC, but instead contain flavored concentrat...

Modeling a pesticide remediation strategy for preparative liquid chromatography using high-performance liquid chromatography

Cannabis sativa L. also known as industrial hemp, is primarily cultivated as source material for cannabinoids cannabidiol (CBD) and ∆9-tetrahydrocannabinol (∆9-THC). Pesticide contamination during plant growth is...

Glandular trichome development, morphology, and maturation are influenced by plant age and genotype in high THC-containing cannabis ( Cannabis sativa L.) inflorescences

Glandular capitate trichomes which form on bract tissues of female inflorescences of high THC-containing Cannabis sativa L. plants are important sources of terpenes and cannabinoids. The influence of plant age an...

Topical cannabidiol is well tolerated in individuals with a history of elite physical performance and chronic lower extremity pain

Cannabidiol (CBD) is a potential therapeutic for pain management. Yet, there exists a dearth of studies of its tolerability and efficacy, especially in special populations. Former elite athletes are a special ...

“It doesn’t make any sense to even try”: the disruptive impact of COVID-19’s first wave on people with chronic pain using medical cannabis in New York

The COVID-19 pandemic disrupted health care but it is unknown how it impacted the lives of people using medical cannabis for chronic pain.

Affiliated with

An official publication of the  Institute of Cannabis Research

• Editorial Board
• Instructions for Authors
• Instructions for Editors
• Sign up for article alerts and news from this journal

Annual Journal Metrics

2022 Citation Impact 3.7 - 2-year Impact Factor 3.4 - 5-year Impact Factor 0.741 - SNIP (Source Normalized Impact per Paper)

2023 Speed 21 days submission to first editorial decision for all manuscripts (Median) 211 days submission to accept (Median)

2023 Usage  596,678 downloads 1,834 Altmetric mentions 

• More about our metrics

Journal of Cannabis Research

ISSN: 2522-5782

• Submission enquiries: Access here and click Contact Us
• General enquiries: [email protected]

• Introduction
• Conclusions
• Article Information

A, The y-axis corresponds to the cannabinoid composition of medical cannabis prescriptions (balanced, CBD-dominant, THC-dominant). The x-axis represents time in years over the sample period (December 2018 to May 2022). The solid fitted lines are locally estimated scatterplot smoothing curves with bandwidths of 0.9 and 2-sided 95% CIs around the smooths. B, Raincloud plots for the daily dose amounts of CBD and THC (x-axis) across the 3 main cannabinoid composition categories (y-axis) are shown. Each dot in the panel corresponds to a single patient-consult dose recording (measured in mg), whereas the boxplot showcases the associated means (denoted by the x), medians (middle line of the box), first and third quartiles (left and right hinges), and 1.5 times the interquartile range left and right of the first and third quartiles, respectively (left and right whiskers), for both CBD and THC. Finally, the split-violin plot visualizes the distribution density of CBD/THC dosing behavior. C, The y-axis represents the daily dose of CBD and THC taken, while the x-axis denotes the number of consultations since commencing treatment. Error bars show 95% CI. CBD indicates cannabidiol; THC, delta-9-tetrahydrocannabinol.

Mean scores on the y-axes correspond to the respective 0 to 100 subscales for general health (A), bodily pain (B), physical functioning (C), and role-physical (D) from the SF-36, respectively. The follow-up on the x-axes represents the number of consultations since commencing treatment. Mean levels of the 4 domain scores are computed for each follow-up consult. The red horizontal lines show the respective pretreatment means at baseline. The gray horizontal lines illustrate the associated means reported by individuals in the 2015 wave of the Household, Income and Labour Dynamics in Australia survey (see reference in text). Error bars show 95% CIs.

Mean scores on the y-axes correspond to the respective 0 to 100 subscales for mental health (A), role-emotional (B), social functioning (C), and vitality (D) from the SF-36, respectively. The follow-up on the x-axes represents the number of consultations since commencing treatment. Mean levels of the 4 domain scores are computed for each follow-up consult. The red horizontal lines show the respective pre-treatment means at baseline. The gray horizontal lines illustrate the associated mean reported by individuals in the 2015 wave of the Household, Income and Labour Dynamics in Australia survey (see reference in text). Error bars show 95% CIs.

eTable 1. Data Availability on Quality of Life (SF-36) Measures by Follow-up

eTable 2. OLS Regression Results, Estimating General Health (Increasing From 0 to 100)

eTable 3. OLS Regression Results, Estimating Bodily Pain (Decreasing From 0 to 100)

eTable 4. OLS Regression Results, Estimating Physical Functioning (Increasing From 0 to 100)

eTable 5. OLS Regression Results, Estimating Role-Physical (Decreasing From 0 to 100)

eTable 6. OLS Regression Results, Estimating Mental Health (Increasing From 0 to 100)

eTable 7. OLS Regression Results, Estimating Role-Emotional (Decreasing From 0 to 100)

eTable 8. OLS Regression Results, Estimating Social Functioning (Increasing From 0 to 100)

eTable 9. OLS Regression Results, Estimating Vitality (Increasing From 0 to 100)

eTable 10. Reported Adverse Events Across Different Severity Levels

eFigure. Flow of Patients Through the Study of the Association of Medicinal Cannabis With Health-Related Quality of Life

Data Sharing Statement

See More About

Sign up for emails based on your interests, select your interests.

Customize your JAMA Network experience by selecting one or more topics from the list below.

• Academic Medicine
• Acid Base, Electrolytes, Fluids
• Allergy and Clinical Immunology
• American Indian or Alaska Natives
• Anesthesiology
• Anticoagulation
• Art and Images in Psychiatry
• Artificial Intelligence
• Assisted Reproduction
• Bleeding and Transfusion
• Caring for the Critically Ill Patient
• Challenges in Clinical Electrocardiography
• Climate and Health
• Climate Change
• Clinical Challenge
• Clinical Decision Support
• Clinical Implications of Basic Neuroscience
• Clinical Pharmacy and Pharmacology
• Complementary and Alternative Medicine
• Consensus Statements
• Coronavirus (COVID-19)
• Critical Care Medicine
• Cultural Competency
• Dental Medicine
• Dermatology
• Diabetes and Endocrinology
• Diagnostic Test Interpretation
• Drug Development
• Electronic Health Records
• Emergency Medicine
• End of Life, Hospice, Palliative Care
• Environmental Health
• Equity, Diversity, and Inclusion
• Facial Plastic Surgery
• Gastroenterology and Hepatology
• Genetics and Genomics
• Genomics and Precision Health
• Global Health
• Guide to Statistics and Methods
• Hair Disorders
• Health Care Delivery Models
• Health Care Economics, Insurance, Payment
• Health Care Quality
• Health Care Reform
• Health Care Safety
• Health Care Workforce
• Health Disparities
• Health Inequities
• Health Policy
• Health Systems Science
• History of Medicine
• Hypertension
• Images in Neurology
• Implementation Science
• Infectious Diseases
• Innovations in Health Care Delivery
• JAMA Infographic
• Law and Medicine
• Leading Change
• Less is More
• LGBTQIA Medicine
• Lifestyle Behaviors
• Medical Coding
• Medical Devices and Equipment
• Medical Education
• Medical Education and Training
• Medical Journals and Publishing
• Mobile Health and Telemedicine
• Narrative Medicine
• Neuroscience and Psychiatry
• Notable Notes
• Nutrition, Obesity, Exercise
• Obstetrics and Gynecology
• Occupational Health
• Ophthalmology
• Orthopedics
• Otolaryngology
• Pain Medicine
• Palliative Care
• Pathology and Laboratory Medicine
• Patient Care
• Patient Information
• Performance Improvement
• Performance Measures
• Perioperative Care and Consultation
• Pharmacoeconomics
• Pharmacoepidemiology
• Pharmacogenetics
• Pharmacy and Clinical Pharmacology
• Physical Medicine and Rehabilitation
• Physical Therapy
• Physician Leadership
• Population Health
• Primary Care
• Professional Well-being
• Professionalism
• Psychiatry and Behavioral Health
• Public Health
• Pulmonary Medicine
• Regulatory Agencies
• Reproductive Health
• Research, Methods, Statistics
• Resuscitation
• Rheumatology
• Risk Management
• Scientific Discovery and the Future of Medicine
• Shared Decision Making and Communication
• Sleep Medicine
• Sports Medicine
• Stem Cell Transplantation
• Substance Use and Addiction Medicine
• Surgical Innovation
• Surgical Pearls
• Teachable Moment
• Technology and Finance
• The Art of JAMA
• The Arts and Medicine
• The Rational Clinical Examination
• Tobacco and e-Cigarettes
• Translational Medicine
• Trauma and Injury
• Treatment Adherence
• Ultrasonography
• Users' Guide to the Medical Literature
• Vaccination
• Venous Thromboembolism
• Veterans Health
• Women's Health
• Workflow and Process
• Wound Care, Infection, Healing

Get the latest research based on your areas of interest.

Others also liked.

• Download PDF
• X Facebook More LinkedIn

Arkell TR , Downey LA , Hayley AC , Roth S. Assessment of Medical Cannabis and Health-Related Quality of Life. JAMA Netw Open. 2023;6(5):e2312522. doi:10.1001/jamanetworkopen.2023.12522

Manage citations:

© 2024

• Permissions

Assessment of Medical Cannabis and Health-Related Quality of Life

• 1 Centre for Human Psychopharmacology, Swinburne University of Technology, Melbourne, Victoria, Australia
• 2 Institute for Breathing and Sleep (IBAS), Austin Hospital, Melbourne, Victoria, Australia
• 3 Department of Economics, University of Western Australia, Crawley, Western Australia, Australia
• 4 Emyria, Leederville, Western Australia, Australia

Question   Is medical cannabis treatment associated with improvements in health-related quality of life?

Findings   In this case series of 3148 patients, significant improvements were reported on all 8 domains of the 36-Item Short Form Health Survey health-related quality of life assessment after commencing treatment with medical cannabis. Improvements were largely sustained over time.

Meaning   These findings suggest that medical cannabis treatment may be associated with improvements in health-related quality of life among patients with a range of health conditions.

Importance   The use of cannabis as a medicine is becoming increasingly prevalent. Given the diverse range of conditions being treated with medical cannabis, as well as the vast array of products and dose forms available, clinical evidence incorporating patient-reported outcomes may help determine safety and efficacy.

Objective   To assess whether patients using medical cannabis report improvements in health-related quality of life over time.

Design, Setting, and Participants   This retrospective case series study was conducted at a network of specialist medical clinics (Emerald Clinics) located across Australia. Participants were patients who received treatment for any indication at any point between December 2018 and May 2022. Patients were followed up every mean (SD) 44.6 (30.1) days. Data for up to 15 follow-ups were reported. Statistical analysis was conducted from August to September 2022.

Exposure   Medical cannabis. Product types and cannabinoid content varied over time in accordance with the treating physician’s clinical judgement.

Main Outcomes and Measures   The main outcome measure was health-related quality of life as assessed using the 36-Item Short Form Health Survey (SF-36) questionnaire.

Results   In this case series of 3148 patients, 1688 (53.6%) were female; 820 (30.2%) were employed; and the mean (SD) age was 55.9 (18.7) years at baseline before treatment. Chronic noncancer pain was the most common indication for treatment (68.6% [2160 of 3148]), followed by cancer pain (6.0% [190 of 3148]), insomnia (4.8% [152 of 3148]), and anxiety (4.2% [132 of 3148]). After commencing treatment with medical cannabis, patients reported significant improvements relative to baseline on all 8 domains of the SF-36, and these improvements were mostly sustained over time. After controlling for potential confounders in a regression model, treatment with medical cannabis was associated with an improvement of 6.60 (95% CI, 4.57-8.63) points to 18.31 (95% CI, 15.86-20.77) points in SF-36 scores, depending on the domain (all P  < .001). Effect sizes (Cohen d ) ranged from 0.21 to 0.72. A total of 2919 adverse events were reported, including 2 that were considered serious.

Conclusions and Relevance   In this case series study, patients using medical cannabis reported improvements in health-related quality of life, which were mostly sustained over time. Adverse events were rarely serious but common, highlighting the need for caution with prescribing medical cannabis.

Medical cannabis was legalized in Australia in November 2016.Aside from Sativex and Epidiolex, all other cannabinoid products are considered unapproved therapeutic goods at the time of this writing. Physicians must obtain regulatory approval to prescribe via one of several special access pathways. These approvals have increased rapidly over the last 2 years and now total more than 332 000. 1 Most approvals have been for chronic pain (55%), followed by anxiety (23%) and insomnia and/or sleep disorders (6%). 2 Major reviews have generally concluded there is evidence for cannabinoid efficacy in the treatment of several conditions: pain in adults, chemotherapy-induced nausea and vomiting, and spasticity associated with multiple sclerosis. 3 - 5 Moderate evidence exists for cannabinoid efficacy in treating secondary sleep disturbances, and there is limited, insufficient, or absent evidence for other conditions. Despite this, enrollment in medical cannabis programs increased 4.5-fold in the US between 2016 and 2020, 6 and a recent survey conducted in the US and Canada found that 27% of all respondents (n = 27 169) had used cannabis for medical purposes at some point. 7

The term medical cannabis encompasses a vast array of products (eg, dried flower, oils, edibles) containing multiple bioactive constituents including, but not limited to, delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). Because patients are using these products to manage such a wide range of health conditions—in addition to the paucity of evidence from randomized clinical trials—clinical evidence incorporating patient-reported outcomes is becoming increasingly recognized as a vital source of safety and efficacy data. 8 , 9 Validated health-related quality of life measures can help provide important, global insights into associations between medical cannabis treatment and daily functioning, physical mobility, and mental health among patients with various and disparate conditions. Here, we examine changes in health-related quality of life over time in a cohort (n = 3148) of Australian patients receiving medical cannabis treatment between 2018 and 2022.

We conducted a retrospective case series analysis of patients prescribed medical cannabis through Emerald Clinics, a network of specialist medical clinics across Australia. After providing informed written consent, patients presenting to Emerald Clinics first undergo a comprehensive consultation with a physician, who reviews their medical history and determines suitability for cannabinoid treatment. In addition to meeting Australia’s regulatory requirements for access to unapproved products (physicians must provide a suitable clinical justification for the use of medical cannabis, including reasons why products included in the Australian Register of Therapeutic Goods are not suitable for treatment of the patient), patients are also required to have exhausted other treatment options for the clinical indication(s) they are presenting with. Moreover, site-specific contraindications for treatment include: (1) urine positive for carboxy-THC (THC-COOH), (2) pregnant and/or breastfeeding, (3) serious cardiac disease, or (4) serious mental health conditions, such as suicidal ideation or a history of psychosis. Patients are instructed to slowly increase their dose via a “start low, go slow” principle. The target dose is determined on a case-by-case basis and is subject to regular reviews by the prescribing physician to assess treatment efficacy and side effects, including any interactions with concomitant medication. Although no official prescribing guidelines exist in Australia, clinical judgement of appropriate dose and product type may be influenced by various factors such as health condition, age, concomitant medications, comorbidities, dose form, and the cost of treatment. This report follows the Strengthening the Reporting of Observational Studies in Epidemiology ( STROBE ) reporting guideline.

In accordance with Australia’s National Statement on Ethical Conduct in Human Research (2007) requirements for exemption from review, data collection commenced in December 2018 and remains ongoing. For this study, we included every observation available (as of May 5, 2022) comprising baseline and up to and including the first 15 follow-up consultations of each patient. We limited the number of follow-ups to 15 as patient numbers become much smaller thereafter (n <80). Besides providing detailed clinical and demographic information (such as age, gender, employment status, and any other medications currently being used), at each consultation patients were also asked to complete several validated questionnaires, including the 36-Item Short Form Health Survey (SF-36) which is the focus of this study. eTable 1 in Supplement 1 presents a consult-by-consult overview of data availability for each measure used in our analysis, but also the mean (SD) time elapsed between consultations. On average, patients attended a mean of (SD) 5.6 (4.9) consultations with a mean (SD) time between consultations of 44.6 (30.1) days.

The primary outcome was change from baseline in patient scores on the SF-36, 10 , 11 a widely used measure of health-related quality of life. The SF-36 includes 36 items which form 8 distinct scales, including: (1) limitations in physical activities due to health problems; (2) limitations in social activities due to physical or emotional problems; (3) limitations in usual role activities due to physical health problems; (4) bodily pain; (5) general mental health (psychological distress and well-being); (6) limitations in usual role activities due to emotional problems; (7) vitality (energy and fatigue); and (8) general health perceptions. Scores can range from 0 to 100, with higher values indicating better outcomes. A recent review considered a 10-point change to be the minimally clinically important difference. 12 Finally, as an additional outcome we also report any reported adverse events.

Our analysis followed a conventional ordinary least squares model. We first estimated a univariate regression using a binary treatment indicator for taking medical cannabis as the sole estimator for each of the 8 domain scores. We then moved to a more complete framework, estimating each score y for patient i at consult t with: y i,t  = β 1 Treatment t + β 2 X i,t + β 3 Z i + ε i,t (equation 1). The coefficient associated with β 1 represents the effect of commencing with the treatment on a patient’s quality of life. X i,t represents a set of control variables that could potentially influence y i,t . These include the number of medications a patient takes daily (at the time of consult), binary indicators for both 8 medication categories (simple analgesics, opioids, antidepressants, benzodiazepines, GABA analogues, antipsychotic medications, compound analgesics, and other pain medications) and 4 primary diagnosis categories (pain, psychiatric, neurological, or other), the number of other comorbidities reported, the patient’s age, gender, and employment status, and a nonlinear treatment trend (equal to the reciprocal of the number of follow-up consults since commencing treatment), as well as month- and year-fixed effects. Furthermore, Z i incorporates patient-fixed effects and ε i,t corresponds to the usual error term. Note that throughout all estimations, 95% CIs were clustered at the patient level while statistical significance was tested at the 5% level ( P  = .05). We then reestimated the same regression analysis displayed in equation 1 for the separate treatment categories, focusing on whether a patient was using a balanced (40% to <60% CBD content), CBD-dominant (≥60% CBD content), or THC-dominant (≥60% THC content) treatment as the main regressors of interest. Effect sizes equivalent to Cohen d were calculated by dividing the associated treatment coefficients in our patient fixed-effects model by the SDs of the respective SF-36 scores at baseline. All analyses were performed in R 4.2.2 (R Project for Statistical Computing) using the lfe package from August to September 2022.

Among the 3148 patients included in this data set, 1688 (53.6%) were female; 820 (30.2%) were employed; and the mean (SD) age was 55.9 (18.7) years at baseline before treatment. Table 1 summarizes the demographics and characteristics of the 3148 patients included in this study. Chronic non-cancer pain was the most common indication for treatment (68.6% [2160 of 3148]), followed by cancer pain (6.0% [190 of 3148]), insomnia (4.8% [152 of 3148]), and anxiety (4.2% [132 of 3148]). Number of comorbidities ranged from 0 to 36, with a mean (SD) of 5.2 (3.9). On average, patients were taking a mean (SD) of 6.58 (4.58) medications a day prior to commencing treatment. The most common medications included simple analgesics (54.1% [1703 of 3148]), opioid analgesics (48.4% [1523 of 3148]), antidepressants (44.5% [1401 of 3148]), benzodiazepines (34.4% [1084 of 3148]), and GABA analogues (22.0% [693 of 3148]). Except for the mental health measure (mean [SD]: 54.06 [22.27]), all mean (SD) pretreatment SF-36 scores were well below the halfway mark on the respective 0 to 100 scales: 40.22 (22.40) for general health; 29.85 (24.16) for bodily pain; 40.99 (30.49) for physical functioning; 14.02 (28.99) for role-physical; 28.37 (37.30) for role-emotional; 36.57 (26.84) for social functioning; and 30.19 (20.83) for vitality.

Figure 1 A shows the percentage of prescriptions by cannabinoid category across the sample period. Prescriptions for CBD-dominant treatments increased consistently from February 2019, and accounted for approximately 80% of all monthly prescriptions (compared with 7.5% and 12.5% for balanced and THC-dominant categories, respectively) at the end of the data collection period. Most of these prescriptions were for orally administered products including oils (n = 14 779 [90.1%]) and capsules (n = 631 [3.8%]). There were only a small number of prescriptions for dried flower for inhalation either alone (n = 244 [1.5%]) or in combination with an oil (n = 168 [1.0%]). Figure 1 B compares daily THC and/or CBD doses across categories. For balanced treatments, the mean (SD) CBD dose was 18.8 (19.2) mg and the mean (SD) THC dose was 18.8 (19.0) mg. For CBD-dominant treatments, the mean (SD) CBD dose was 97.1 (155.0) mg and the mean (SD) THC dose was 8.7 (12.2) mg. For THC-dominant treatments, the mean (SD) CBD dose was 5.0 (6.9) mg while the mean (SD) THC dose was 35.9 (71.6) mg. As Figure 1 C illustrates, the mean (SD) daily CBD dose initially increased from 51.4 (128.4) mg at follow-up 1 (approximately 45 days after treatment initiation) to 72.2 (217.6) mg at follow-up 2 (approximately 90 days after treatment initiation), but then stayed relatively stable across subsequent consults. The mean (SD) daily THC dose, on the other hand, increased steadily over time from 6.5 (8.2) mg at follow-up 1 to 25.8 (23.6) mg at follow-up 15 (approximately 675 days after treatment initiation).

Figure 2 and Figure 3 display mean scores for all SF-36 domains across 15 follow-up consults, with the red horizontal line showing the mean score at baseline as a pretreatment reference point. The gray line provides a comparison to the mean Australian score as reported in the 2015 wave of the Household, Income and Labour Dynamics in Australia survey. 13 As can be seen in Figure 2 , patients reported an increase relative to baseline on all 4 physical component domains, yet scores remain substantially lower than the mean Australian score. For physical functioning ( Figure 2 C), mean scores regressed toward baseline at follow-up 10, but did not decrease beyond this point. For all other physical domains, gains relative to baseline were maintained across all 15 follow-ups. For bodily pain (Figure 2B) and role-physical ( Figure 2 D), the change from baseline was statistically significant across all time points ( P  < .05). Figure 3 shows a similar if not greater (relative to physical component domains) improvement in mental health domain scores. We observed pronounced and statistically significant improvements on all 4 domains across all 15 follow-ups ( P  < .01). For both Figure 2 and Figure 3 , wider 95% CIs at later time points (ie, longer treatment duration) reflect smaller patient numbers.

Table 2 reports the ordinary least squares regression results for all 8 SF-36 domain scores. Here, we only display the primary coefficient of interest with the corresponding 95% CIs, R 2 value, and effect size (Cohens d ). The complete regression output can be found in eTables 2 to 9 in Supplement 1 . Our complete regression model accounts for a relatively high proportion of variance (41% to 79%) in SF-36 domain scores. Overall ( Table 2 ), treatment with medical cannabis was associated with improvements on all physical and mental health domain scores: general health (β = 8.42; 95% CI, 6.73-10.11; P  < .001); bodily pain (β = 17.34; 95% CI, 15.41-19.27; P  < .001); physical functioning (β = 6.60; 95% CI, 4.57-8.63; P  < .001); role-physical (β = 16.81; 95% CI, 13.58-20.04, P  < .001); mental health (β = 11.00; 95% CI, 9.32-12.68; P  < .001); role-emotional (β = 14.19; 95% CI, 10.01-18.36; P  < .001); social functioning (β = 18.31; 95% CI, 15.86-20.77; P  < .001); and vitality (β = 12.91; 95% CI, 11.02-14.79; P  < .001). Effect sizes were small-moderate in magnitude, ranging from 0.21 to 0.72. For all domains except for physical functioning and role-physical, balanced products were associated with marginally greater improvements than either CBD-dominant or THC-dominant products. CBD-dominant products were associated with largest improvements on the role-physical domain, while THC-dominant products were associated with largest improvements on the physical functioning domain.

A total of 2919 adverse events were reported over the sampling period (eTable 10 in Supplement 1 ). Most were either mild (n = 1905) or moderate (n = 922); 86 were severe. Two adverse events were considered serious, including 1 incidence of hallucination. In order of frequency, adverse events included sedation and/or sleepiness (13.1% of patients), dry mouth (11.4%), lethargy and/or tiredness (7.4%), dizziness (7.1%), difficulty concentrating (6.4%), nausea (6.3%), diarrhea and/or loose stools (4.9%), feeling high (4.7%), increased appetite (3.7%), headache (3.2%), anxiety and/or panic attack (2.7%), vivid dreams (1.7%), hallucination (1.4%), and impaired coordination (1.3%). The incidence of adverse events did not differ significantly across cannabinoid composition categories.

In this retrospective case series, patients reported improvements on all 8 health-related quality of life domains assessed by the SF-36 after commencing treatment with medical cannabis. In our most complete regression model, observed treatment effects suggest improvements relative to baseline (pretreatment) ranging from 6.60 to 18.31 points. Even though the mean daily THC/CBD dose differed considerably across the balanced (18.8 mg THC; 18.8 mg CBD), CBD-dominant (8.7 mg THC; 97.1 mg CBD) and THC-dominant (35.9 mg THC; 5.0 mg CBD) treatment categories, estimated treatment effects were very similar. The mean daily THC dose increased consistently across the sample period from 6.5 mg at follow-up 1 to 25.8 mg at follow-up 15, consistent with a standard dose titration protocol. The mean CBD dose, on the other hand, stayed relatively stable across the sample period after reaching 72.2 mg at follow-up 2.

Commensurate with the Therapeutic Goods Administration data reflecting broader prescription patterns across Australia, 2 chronic noncancer pain was by far the most common primary diagnosis in this sample population (n = 2160), followed by cancer pain (n = 190), insomnia (n = 152), and anxiety (n = 132). As might be expected given the high incidence of pain conditions, almost half of all patients were using simple and/or opioid analgesics at baseline. Patient-reported bodily pain and physical functioning scores at baseline were more than 40% below the Australian mean score, while patient-reported role-physical scores (limitations in usual role activities due to physical health problems) were more than 70% below the Australian mean. Patient-reported social functioning and role-emotional (limitations in usual role activities due to emotional problems) were also more than 40% below the Australian mean. Considering this, the estimated treatment effects reported here (ranging from 6.60 to 18.31 points) suggest substantial absolute gains across all functional domains, although it is important to contextualize the magnitude of these changes within the broader literature.

In a recent systematic review and meta-analysis of randomized clinical trials of medical cannabis for chronic pain (n = 32 trials with 5174 patients), oral medical cannabis was associated with a 4% increase in the proportion of patients experiencing an improvement of more than 10 points (the minimally clinically important difference) on the physical functioning scale of the SF-36 relative to placebo. 12 No evidence was found for improvements on the role-emotional, role-physical, or social functioning scales; however, the median follow-up time was only 50 days (maximum: 154 days), and there was considerable variability in active drug type and route of administration. Here, clinically important improvements (>10 points) were observed for the role-emotional, role-physical, and social functioning scales, with associated effect sizes (0.38 to 0.68), suggesting considerable clinical gains over the long term.

Pritchett et al 14 reported significant improvements on 5 SF-36 domains when comparing scores prior to commencing medical cannabis with posttreatment scores. In a sample of 2183 patients in Florida, large mean differences of 43.64, 35.15 and 26.55 points were noted for the social functioning, bodily pain, and physical functioning scales. However, pretreatment scores were retrospectively reported by patients, which limits their reliability, and only a single posttreatment measure was obtained. To better determine the long-term effects of medical cannabis treatment, Safakish et al 15 examined changes on the SF-12 (a short-form version of the SF-36) over 12 months in 751 patients with chronic pain commencing medical cannabis treatment. While statistically significant improvements were seen on both the physical and mental health domains, these changes were notably smaller than those seen here. Nevertheless, patients did experience a clinically important reduction in pain severity of 2.09 points on the brief pain inventory.

Pain severity was also significantly reduced in 274 patients with chronic pain when assessed 6 months after treatment, as was pain interference and most social and emotional disability scores on the S-TOPS. 16 An analysis of 190 patients with chronic pain in the UK Medical Cannabis Registry likewise revealed improvements on a range of scales (including the EQ-5D, Sleep Quality Scale, General Anxiety Disorder-7) at 1, 3, and 6 months relative to baseline. 17 Changes in EQ-5D scores after 6 weeks of treatment were less consistent in a study involving 214 Canadian patients commencing medical cannabis treatment; improvements were seen for patients with anxiety and PTSD, but not for patients with arthritis and other rheumatic disorders or sleep disorders. 18 Despite an improvement in quality of life among patients with anxiety, there were no significant changes in the anxiety subscale of the Depression, Anxiety and Stress Scale. These data suggest that treatment with medical cannabis may, in some circumstances, improve quality of life without reducing the severity of the underlying condition.

A recent study by Aviram et al 19 provides some evidence to support this notion. In a sample of 429 patients who consumed medical cannabis via inflorescence inhalation and were followed up monthly over 6 months, there was no change over time in the least, average, and worst weekly pain intensities, or in pain frequency. There was, however, an increase in the proportion of patients reporting better quality of life on the EQ-5D and a decrease in the proportion reporting consumption of analgesic medications at subsequent time points. There was also a reduction in the mean (SD) morphine equivalent dose of opioid analgesics from 21 (91) mg at baseline to 5.2 (27) mg at 6 months, suggesting a possible opioid-sparing association with medical cannabis, consistent with several other recent studies.( 20 - 22 ) These data are also supported by epidemiological evidence for reduced state-level opioid overdose mortality rates in US states with medical cannabis laws, 23 although as Noori et al 24 caution in a recent review, 24 extant evidence from randomized and observational studies is of very low certainty.

This study is limited by the use of a retrospective case series design without a control, which restricts what conclusions can be drawn around treatment efficacy, and limits generalizability to other clinical populations. Given the ongoing increase in medical cannabis prescribing, other clinics should strongly consider implementing a similarly rigorous clinical data collection protocol in order to monitor clinical safety and patient-reported outcomes associated with medical cannabis use. As most patients began treatment at some point during the sampling period, patient numbers at later consults (ie, reflecting longer treatment periods) are lower than patient numbers at earlier consults. As a result, mean SF-36 domain scores show considerably greater variability at later consults and should be interpreted with caution. We intend to conduct a follow-up study in the future with larger patient numbers and a longer follow-up period. Furthermore, patients were not required to complete the questionnaires described here, and so these data may be biased upwards if patients experiencing a positive effect of medical cannabis were more likely to respond. Finally, the clinical care model used by Emerald Clinics may have also contributed to perceived improvements in quality of life.

This study suggests a favorable association between medical cannabis treatment and quality of life among patients with a diverse range of conditions. However, clinical evidence for cannabinoid efficacy remains limited, and further high-quality trials are required. While we cannot exclude the possibility that adverse events may have been caused in whole or part by the disease state and concomitant medications, the relatively high incidence of adverse events still affirms the need for caution with THC prescribing and careful identification of patients with contraindications.

Accepted for Publication: March 27, 2023.

Published: May 9, 2023. doi:10.1001/jamanetworkopen.2023.12522

Open Access: This is an open access article distributed under the terms of the CC-BY-NC-ND License . © 2023 Arkell TR et al. JAMA Network Open .

Corresponding Author: Thomas R. Arkell, PhD, Centre for Human Psychopharmacology, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia ( [email protected] ).

Author Contributions: Dr Roth had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Arkell, Downey, Hayley.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Arkell, Downey, Hayley.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Roth.

Administrative, technical, or material support: Downey, Hayley, Roth.

Supervision: Downey, Hayley, Roth.

Conflict of Interest Disclosures: Dr Arkell reported receiving personal fees from Althea, personal fees from bod, personal fees from NUBU Pharmaceuticals, personal fees from the International College of Cannabinoid Medicine, and grants from Barbara Dicker Foundation outside the submitted work. Dr Downey reported receiving grants from National Health & Medical Research Council, grants from Cannvalate, and grants from Barbara Dicker Foundation outside the submitted work. Dr Hayley reported receiving grants from Cannvalate, grants from Rebecca L. Cooper Foundation for the Al and Val Rosenstrauss Fellowship (F2021894), grants from Barbara Dicker Foundation, and grants from Road Safety Innovation Fund outside the submitted work. No other disclosures were reported.

Funding/Support: Emyria funded the collection of data for this study from 2018 to 2022, and Dr Roth conducted statistical analysis as a paid employee of the company. Funding for development of the manuscript was provided to Drs Arkell and Hayley, and Prof Downey via a grant from Emyria to Swinburne University.

Role of the Funder/Sponsor: The funder had no role in the design and conduct of the study; analysis and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication. The funder (Emyria) did have a role in the collection and management of the data (from 2018 to 2022).

Data Sharing Statement: See Supplement 2 .

• Register for email alerts with links to free full-text articles
• Access PDFs of free articles
• Manage your interests
• Save searches and receive search alerts

• Program Finder
• Admissions Services
• Course Directory
• Academic Calendar
• Hybrid Campus
• Lecture Series
• Convocation
• Strategy and Development
• Implementation and Impact
• Integrity and Oversight
• In the School
• In the Field
• In Baltimore
• Resources for Practitioners
• Articles & News Releases
• In The News
• Statements & Announcements
• At a Glance
• Student Life
• Strategic Priorities
• Inclusion, Diversity, Anti-Racism, and Equity (IDARE)
• What is Public Health?

The Evidence—and Lack Thereof—About Cannabis

Research is still needed on cannabis’s risks and benefits. 

Lindsay Smith Rogers

Although the use and possession of cannabis is illegal under federal law, medicinal and recreational cannabis use has become increasingly widespread.

Thirty-eight states and Washington, D.C., have legalized medical cannabis, while 23 states and D.C. have legalized recreational use. Cannabis legalization has benefits, such as removing the product from the illegal market so it can be taxed and regulated, but science is still trying to catch up as social norms evolve and different products become available. 

In this Q&A, adapted from the August 25 episode of Public Health On Call , Lindsay Smith Rogers talks with Johannes Thrul, PhD, MS , associate professor of Mental Health , about cannabis as medicine, potential risks involved with its use, and what research is showing about its safety and efficacy. 

Do you think medicinal cannabis paved the way for legalization of recreational use?

The momentum has been clear for a few years now. California was the first to legalize it for medical reasons [in 1996]. Washington and Colorado were the first states to legalize recreational use back in 2012. You see one state after another changing their laws, and over time, you see a change in social norms. It's clear from the national surveys that people are becoming more and more in favor of cannabis legalization. That started with medical use, and has now continued into recreational use.

But there is a murky differentiation between medical and recreational cannabis. I think a lot of people are using cannabis to self-medicate. It's not like a medication you get prescribed for a very narrow symptom or a specific disease. Anyone with a medical cannabis prescription, or who meets the age limit for recreational cannabis, can purchase it. Then what they use it for is really all over the place—maybe because it makes them feel good, or because it helps them deal with certain symptoms, diseases, and disorders.

Does cannabis have viable medicinal uses?

The evidence is mixed at this point. There hasn’t been a lot of funding going into testing cannabis in a rigorous way. There is more evidence for certain indications than for others, like CBD for seizures—one of the first indications that cannabis was approved for. And THC has been used effectively for things like nausea and appetite for people with cancer.

There are other indications where the evidence is a lot more mixed. For example, pain—one of the main reasons that people report for using cannabis. When we talk to patients, they say cannabis improved their quality of life. In the big studies that have been done so far, there are some indications from animal models that cannabis might help [with pain]. When we look at human studies, it's very much a mixed bag. 

And, when we say cannabis, in a way it's a misnomer because cannabis is so many things. We have different cannabinoids and different concentrations of different cannabinoids. The main cannabinoids that are being studied are THC and CBD, but there are dozens of other minor cannabinoids and terpenes in cannabis products, all of varying concentrations. And then you also have a lot of different routes of administration available. You can smoke, vape, take edibles, use tinctures and topicals. When you think about the explosion of all of the different combinations of different products and different routes of administration, it tells you how complicated it gets to study this in a rigorous way. You almost need a randomized trial for every single one of those and then for every single indication.

What do we know about the risks of marijuana use?  

Cannabis use disorder is a legitimate disorder in the DSM. There are, unfortunately, a lot of people who develop a problematic use of cannabis. We know there are risks for mental health consequences. The evidence is probably the strongest that if you have a family history of psychosis or schizophrenia, using cannabis early in adolescence is not the best idea. We know cannabis can trigger psychotic symptoms and potentially longer lasting problems with psychosis and schizophrenia. 

It is hard to study, because you also don't know if people are medicating early negative symptoms of schizophrenia. They wouldn't necessarily have a diagnosis yet, but maybe cannabis helps them to deal with negative symptoms, and then they develop psychosis. There is also some evidence that there could be something going on with the impact of cannabis on the developing brain that could prime you to be at greater risk of using other substances later down the road, or finding the use of other substances more reinforcing. 

What benefits do you see to legalization?

When we look at the public health landscape and the effect of legislation, in this case legalization, one of the big benefits is taking cannabis out of the underground illegal market. Taking cannabis out of that particular space is a great idea. You're taking it out of the illegal market and giving it to legitimate businesses where there is going to be oversight and testing of products, so you know what you're getting. And these products undergo quality control and are labeled. Those labels so far are a bit variable, but at least we're getting there. If you're picking up cannabis at the street corner, you have no idea what's in it. 

And we know that drug laws in general have been used to criminalize communities of color and minorities. Legalizing cannabis [can help] reduce the overpolicing of these populations.

What big questions about cannabis would you most like to see answered?

We know there are certain, most-often-mentioned conditions that people are already using medical cannabis for: pain, insomnia, anxiety, and PTSD. We really need to improve the evidence base for those. I think clinical trials for different cannabis products for those conditions are warranted.

Another question is, now that the states are getting more tax revenue from cannabis sales, what are they doing with that money? If you look at tobacco legislation, for example, certain states have required that those funds get used for research on those particular issues. To me, that would be a very good use of the tax revenue that is now coming in. We know, for example, that there’s a lot more tax revenue now that Maryland has legalized recreational use. Maryland could really step up here and help provide some of that evidence.

Are there studies looking into the risks you mentioned?

Large national studies are done every year or every other year to collect data, so we already have a pretty good sense of the prevalence of cannabis use disorder. Obviously, we'll keep tracking that to see if those numbers increase, for example, in states that are legalizing. But, you wouldn't necessarily expect to see an uptick in cannabis use disorder a month after legalization. The evidence from states that have legalized it has not demonstrated that we might all of a sudden see an increase in psychosis or in cannabis use disorder. This happens slowly over time with a change in social norms and availability, and potentially also with a change in marketing. And, with increasing use of an addictive substance, you will see over time a potential increase in problematic use and then also an increase in use disorder.

If you're interested in seeing if cannabis is right for you, is this something you can talk to your doctor about?

I think your mileage may vary there with how much your doctor is comfortable and knows about it. It's still relatively fringe. That will very much depend on who you talk to. But I think as providers and professionals, everybody needs to learn more about this, because patients are going to ask no matter what.

Lindsay Smith Rogers, MA, is the producer of the Public Health On Call podcast , an editor for Expert Insights , and the director of content strategy for the Johns Hopkins Bloomberg School of Public Health.

Could Medical Marijuana Help Address the Opioid Epidemic?

Policy Is Public Health

Medical Marijuana Laws Linked to Health and Labor Supply Benefits in Older Adults

Related Content

How Dangerous is Dengue?

Research Identifies Characteristics of Cities That Would Support Young People’s Mental Health

Alumni Spotlight: Junrui Di, PhD '19

Child Diarrhea Has a Cheap and Easy Fix—Why Isn’t It Reaching Patients?

How Abortion Trigger Laws Impact Mental Health

• Skip to main content
• Keyboard shortcuts for audio player

• Your Health
• Treatments & Tests
• Health Inc.
• Public Health

After 50 Years, U.S. Opens The Door To More Cannabis Crops For Scientists

More than 30 states have medical marijuana programs — yet scientists are only allowed to use cannabis plants from one U.S. source for their research. That's set to change, as the federal government begins to add more growers to the mix. Drew Angerer/Getty Images hide caption

More than 30 states have medical marijuana programs — yet scientists are only allowed to use cannabis plants from one U.S. source for their research. That's set to change, as the federal government begins to add more growers to the mix.

After more than 50 years, the federal government is lifting a roadblock to cannabis research that scientists and advocates say has hindered rigorous studies of the plant and possible drug development.

Since 1968, U.S. researchers have been allowed to use cannabis from only one domestic source : a facility based at the University of Mississippi, through a contract with the National Institute on Drug Abuse (NIDA).

That changed earlier this month, when the Drug Enforcement Administration announced it's in the process of registering several additional American companies to produce cannabis for medical and scientific purposes.

It's a move that promises to accelerate understanding of the plant's health effects and possible therapies for treating conditions — chronic pain, the side effects of chemotherapy, multiple sclerosis and mental illness, among many others — that are yet to be well studied .

Shots - Health News

How one boy's fight with epilepsy led to the first marijuana-derived pharmaceutical.

"This is a momentous decision," says Rick Doblin, executive director of the Multidisciplinary Association for Psychedelic Studies (MAPS), which has spearheaded research into other Schedule 1 drugs — the most restrictive class of controlled substance, which the federal government defines as "drugs with no currently accepted medical use."

"This is the last political obstruction of research with Schedule 1 drugs," he says.

About one-third of Americans currently live in a state where recreational marijuana is legal — and more than 30 states have medical marijuana programs . Yet scientists still aren't allowed to simply use the cannabis sold at state-licensed dispensaries for their clinical research because cannabis remains illegal under federal law.

Medical Marijuana's 'Catch-22': Limits On Research Hinder Patient Relief

"It is a big disconnect," says Dr. Igor Grant , a psychiatry professor and director of the Center for Medicinal Cannabis Research at University of California, San Diego.

The new DEA decision doesn't resolve the conflict between federal and state laws, but it does offer researchers a new, federally sanctioned pipeline for more products and strains of cannabis.

"We'll see a decade or more of explosive cannabis research and potential new therapies," says Dr. Steve Groff, founder and chairman of Groff North America , one of three companies that has publicly announced it has preliminary approval from the federal government to cultivate cannabis for research.

A long-running fight to overturn federal "monopoly"

Despite their efforts, scientists have encountered administrative and legal hurdles to growing pharmaceutical-grade cannabis for decades.

In 2001, Dr. Lyle Craker, a prominent plant biologist, first applied for a license to cultivate marijuana for research — only to encounter years of delay that kicked off a prolonged court battle with the DEA, which has to greenlight research into Schedule 1 drugs like cannabis.

"There's thousands of different cannabis varieties that all have unique chemical profiles and produce unique clinical effects, but we didn't have access to that normal diversity," says Dr. Sue Sisley , a cannabis researcher and president of the Scottsdale Research Institute, which also received preliminary DEA approval to produce cannabis for research.

Only in 2016 did the federal government signal a change in policy that would open the door for new growers, but applications to do so languished for years. Craker and others ended up suing the federal government over the delay.

Psychiatrist Explores Possible Benefits Of Treating PTSD With Ecstasy Or Cannabis

Sisley has long taken issue with the supply of cannabis coming from the NIDA facility in Mississippi — in particular, how it's processed. She used cannabis produced there in her recently published clinical trial on treating PTSD in military veterans.

She describes the product as an "anemic" greenish powder.

"It's very difficult to overcome the placebo effect when you have something that diluted," she says.

The 76-person study, which took 10 years to complete, concluded that smoked cannabis was generally well tolerated and did not lead to deleterious effects in this group. But it also did not find any statistically significant difference in abating the symptoms of PTSD when compared to a placebo.

For Grant of UCSD, the problem with the long-standing supply of cannabis isn't so much the quality, but the lack of different products like edibles and oils and of cannabis strains with varying concentrations of CBD and THC, the plant's main psychoactive ingredient.

"We don't have enough research on the kind of marijuana products that people in the real world are using," he says.

As CBD Oils Become More Popular, The FDA Considers Whether To Set New Rules

Because of the limited domestic supply, some researchers have resorted to importing cannabis from outside the U.S. — a legal but wildly counterintuitive arrangement that is "arduous" and prone to hiccups, says Sisley.

The constraints on research cannabis also has impeded the pathway to drug development because the NIDA facility's cannabis could only be used for academic research, not for prescription drug development . A drug studied in phase 3 clinical trials — what's required before submitting for approval from the Food and Drug Administration — must be the same as what's later marketed.

"The NIDA monopoly has primarily been why we have medical marijuana in the states, but we don't have medical marijuana through the FDA," says Doblin of MAPS. "It's a fundamental change that we can now have drug development with domestic supplies."

A few barriers still remain

The few companies that will soon land DEA spots to cultivate cannabis have an eager marketplace of researchers who are "clamoring" for the chance to study the scientific properties and medical potential of the plant, says Groff, whose company is up for DEA approval and who also has an FDA project to study the antimicrobial properties of cannabis for killing dangerous bacteria like MRSA .

By the end of next year, Groff anticipates his company will be producing up to 5,000 pounds of marijuana per year, offering researchers a "full menu of customizable options."

Biopharmaceutical Research Company — a third company that will soon cultivate cannabis with a DEA license — already has dozens of agreements in place with U.S. researchers and is hearing from more academic institutions, drugmakers and biotech companies in the wake of the change in policy, says CEO George Hodgin.

"Now there's a very clear, approved and legal path for them to legally enter the cannabis space in the United States," says Hodgin.

The Coronavirus Crisis

'illegal to essential': how the coronavirus is boosting the legal cannabis industry.

Washington State University's Center for Cannabis Policy, Research and Outreach is one of the places that expects to eventually procure cannabis from Hodgin's business.

"It's definitely a big step in the right direction because the industry is moving much faster than we are in research," says Michael McDonell , an associate professor of medicine and director of the university's cannabis center.

But he also points out that even with more growers coming online, it's still by no means easy to study cannabis, because researchers need a special license when working with a Schedule 1 drug and grants to conduct these studies are hard to come by.

Despite the widespread use of marijuana in the U.S., research into the medical potential of other Schedule 1 drugs like MDMA (ecstasy) is much further along than cannabis .

UCSD's Grant says the biggest leap forward for research would come from moving cannabis out of the Schedule 1 drug classification. "If that were to happen," he says, "that would solve a lot of these problems that we've been talking about."

• medical cannabis
• medical marijuana

Cannabis (Marijuana) DrugFacts

What is marijuana.

Marijuana refers to the dried leaves, flowers, stems, and seeds from the Cannabis sativa or Cannabis indica plant. The plant contains the mind-altering chemical THC and other similar compounds. Extracts can also be made from the cannabis plant (see " Marijuana Extracts ").

According to the National Survey on Drug Use and Health , cannabis (marijuana) is one of the most used drugs in the United States, and its use is widespread among young people. In 2021, 35.4% of young adults aged 18 to 25 (11.8 million people) reported using marijuana in the past year. 1 According to the Monitoring the Future survey , rates of past year marijuana use among middle and high school students have remained relatively steady since the late 1990s. In 2022, 30.7% of 12th graders reported using marijuana in the past year and 6.3% reported using marijuana daily. In addition, many young people also use vaping devices to consume cannabis products. In 2022, nearly 20.6% of 12th graders reported that they vaped marijuana in the past year and 2.1% reported that they did so daily. 2

Legalization of marijuana for medical use or adult recreational use in a growing number of states may affect these views. Read more about marijuana as medicine in our DrugFacts: Marijuana as Medicine .

How do people use marijuana?

People smoke marijuana in hand-rolled cigarettes (joints) or in pipes or water pipes (bongs). They also smoke it in blunts—emptied cigars that have been partly or completely refilled with marijuana. To avoid inhaling smoke, some people are using vaporizers. These devices pull the active ingredients (including THC) from the marijuana and collect their vapor in a storage unit. A person then inhales the vapor, not the smoke. Some vaporizers use a liquid marijuana extract.

People can mix marijuana in food ( edibles ), such as brownies, cookies, or candy, or brew it as a tea. A newly popular method of use is smoking or eating different forms of THC-rich resins (see " Marijuana Extracts ").

Marijuana Extracts

Smoking THC-rich resins extracted from the marijuana plant is on the rise. People call this practice dabbing . These extracts come in various forms, such as:

• hash oil or honey oil —a gooey liquid
• wax or budder —a soft solid with a texture like lip balm
• shatter —a hard, amber-colored solid

These extracts can deliver extremely large amounts of THC to the body, and their use has sent some people to the emergency room. Another danger is in preparing these extracts, which usually involves butane (lighter fluid). A number of people have caused fires and explosions and have been seriously burned from using butane to make extracts at home. 3,4

How does marijuana affect the brain?

Marijuana has both short-and long-term effects on the brain.

Short-Term Effects

When a person smokes marijuana, THC quickly passes from the lungs into the bloodstream. The blood carries the chemical to the brain and other organs throughout the body. The body absorbs THC more slowly when the person eats or drinks it. In that case, they generally feel the effects after 30 minutes to 1 hour.

THC acts on specific brain cell receptors that ordinarily react to natural THC-like chemicals. These natural chemicals play a role in normal brain development and function.

Marijuana over activates parts of the brain that contain the highest number of these receptors. This causes the "high" that people feel. Other effects include:

• altered senses (for example, seeing brighter colors)
• altered sense of time
• changes in mood
• impaired body movement
• difficulty with thinking and problem-solving
• impaired memory
• hallucinations (when taken in high doses)
• delusions (when taken in high doses)
• psychosis (risk is highest with regular use of high potency marijuana)

Long-Term Effects

Marijuana also affects brain development. When people begin using marijuana as teenagers, the drug may impair thinking, memory, and learning functions and affect how the brain builds connections between the areas necessary for these functions. Researchers are still studying how long marijuana's effects last and whether some changes may be permanent.

For example, a study from New Zealand conducted in part by researchers at Duke University showed that people who started smoking marijuana heavily in their teens and had an ongoing marijuana use disorder lost an average of 8 IQ points between ages 13 and 38. The lost mental abilities didn't fully return in those who quit marijuana as adults. Those who started smoking marijuana as adults didn't show notable IQ declines. 5

In another recent study on twins, those who used marijuana showed a significant decline in general knowledge and in verbal ability (equivalent to 4 IQ points) between the preteen years and early adulthood, but no predictable difference was found between twins when one used marijuana and the other didn't. This suggests that the IQ decline in marijuana users may be caused by something other than marijuana, such as shared familial factors (e.g., genetics, family environment). 6 NIDA’s Adolescent Brain Cognitive Development (ABCD) study, a major longitudinal study, is tracking a large sample of young Americans from late childhood to early adulthood to help clarify how and to what extent marijuana and other substances, alone and in combination, affect adolescent brain development. Read more about the ABCD study on our Longitudinal Study of Adolescent Brain and Cognitive Development (ABCD Study) webpage.

A Rise in Marijuana’s THC Levels

The amount of THC in marijuana has been increasing steadily over the past few decades. 7 For a person who's new to marijuana use, this may mean exposure to higher THC levels with a greater chance of a harmful reaction. Higher THC levels may explain the rise in emergency room visits involving marijuana use.

The popularity of edibles also increases the chance of harmful reactions. Edibles take longer to digest and produce a high. Therefore, people may consume more to feel the effects faster, leading to dangerous results.

Higher THC levels may also mean a greater risk for addiction if people are regularly exposing themselves to high doses.

What are the other health effects of marijuana?

Marijuana use may have a wide range of effects, both physical and mental.

Physical Effects

• Breathing problems. Marijuana smoke irritates the lungs, and people who smoke marijuana frequently can have the same breathing problems as those who smoke tobacco. These problems include daily cough and phlegm, more frequent lung illness, and a higher risk of lung infections. Researchers so far haven't found a higher risk for lung cancer in people who smoke marijuana. 8
• Increased heart rate. Marijuana raises heart rate for up to 3 hours after smoking. This effect may increase the chance of heart attack. Older people and those with heart problems may be at higher risk.
• Problems with child development during and after pregnancy. One study found that about 20% of pregnant women 24-years-old and younger screened positive for marijuana. However, this study also found that women were about twice as likely to screen positive for marijuana use via a drug test than they state in self-reported measures. 9 This suggests that self-reported rates of marijuana use in pregnant females is not an accurate measure of marijuana use and may be underreporting their use. Additionally, in one study of dispensaries, nonmedical personnel at marijuana dispensaries were recommending marijuana to pregnant women for nausea, but medical experts warn against it. This concerns medical experts because marijuana use during pregnancy is linked to lower birth weight 10 and increased risk of both brain and behavioral problems in babies. If a pregnant woman uses marijuana, the drug may affect certain developing parts of the fetus's brain. Children exposed to marijuana in the womb have an increased risk of problems with attention, 11 memory, and problem-solving compared to unexposed children. 12 Some research also suggests that moderate amounts of THC are excreted into the breast milk of nursing mothers. 13 With regular use, THC can reach amounts in breast milk that could affect the baby's developing brain. Other recent research suggests an increased risk of preterm births. 27 More research is needed. Read our Marijuana Research Report for more information about marijuana and pregnancy.
• Intense nausea and vomiting. Regular, long-term marijuana use can lead to some people to develop Cannabinoid Hyperemesis Syndrome. This causes users to experience regular cycles of severe nausea, vomiting, and dehydration, sometimes requiring emergency medical attention. 14

Reports of Deaths Related to Vaping

The Food and Drug Administration has alerted the public to hundreds of reports of serious lung illnesses associated with vaping, including several deaths. They are working with the Centers for Disease Control and Prevention (CDC) to investigate the cause of these illnesses. Many of the suspect products tested by the states or federal health officials have been identified as vaping products containing THC, the main psychotropic ingredient in marijuana. Some of the patients reported a mixture of THC and nicotine; and some reported vaping nicotine alone. No one substance has been identified in all of the samples tested, and it is unclear if the illnesses are related to one single compound. Until more details are known, FDA officials have warned people not to use any vaping products bought on the street, and they warn against modifying any products purchased in stores. They are also asking people and health professionals to report any adverse effects. The CDC has posted an information page for consumers.

Mental Effects

Long-term marijuana use has been linked to mental illness in some people, such as:

• temporary hallucinations
• temporary paranoia
• worsening symptoms in patients with schizophrenia —a severe mental disorder with symptoms such as hallucinations, paranoia, and disorganized thinking

Marijuana use has also been linked to other mental health problems, such as depression, anxiety, and suicidal thoughts among teens. However, study findings have been mixed.

Are there effects of inhaling secondhand marijuana smoke?

Failing a drug test.

While it's possible to fail a drug test after inhaling secondhand marijuana smoke, it's unlikely. Studies show that very little THC is released in the air when a person exhales. Research findings suggest that, unless people are in an enclosed room, breathing in lots of smoke for hours at close range, they aren't likely to fail a drug test. 15,16 Even if some THC was found in the blood, it wouldn't be enough to fail a test.

Getting High from Passive Exposure?

Similarly, it's unlikely that secondhand marijuana smoke would give nonsmoking people in a confined space a high from passive exposure. Studies have shown that people who don't use marijuana report only mild effects of the drug from a nearby smoker, under extreme conditions (breathing in lots of marijuana smoke for hours in an enclosed room). 17

Other Health Effects?

More research is needed to know if secondhand marijuana smoke has similar health risks as secondhand tobacco smoke. A recent study on rats suggests that secondhand marijuana smoke can do as much damage to the heart and blood vessels as secondhand tobacco smoke. 20 But researchers haven't fully explored the effect of secondhand marijuana smoke on humans. What they do know is that the toxins and tar found in marijuana smoke could affect vulnerable people, such as children or people with asthma.

How Does Marijuana Affect a Person's Life?

Compared to those who don't use marijuana, those who frequently use large amounts report the following:

• lower life satisfaction
• poorer mental health
• poorer physical health
• more relationship problems

People also report less academic and career success. For example, marijuana use is linked to a higher likelihood of dropping out of school. 18 It's also linked to more job absences, accidents, and injuries. 19

Is marijuana a gateway drug?

Use of alcohol, tobacco, and marijuana are likely to come before use of other drugs. 21,22 Animal studies have shown that early exposure to addictive substances, including THC, may change how the brain responds to other drugs. For example, when rodents are repeatedly exposed to THC when they're young, they later show an enhanced response to other addictive substances—such as morphine or nicotine—in the areas of the brain that control reward, and they're more likely to show addiction-like behaviors. 23,24

Although these findings support the idea of marijuana as a "gateway drug," the majority of people who use marijuana don't go on to use other "harder" drugs. It's also important to note that other factors besides biological mechanisms, such as a person’s social environment, are also critical in a person’s risk for drug use and addiction. Read more about marijuana as a gateway drug in our Marijuana Research Report .

Can a person overdose on marijuana?

An overdose occurs when a person uses enough of the drug to produce life-threatening symptoms or death. There are no reports of teens or adults dying from marijuana alone. However, some people who use marijuana can feel some very uncomfortable side effects, especially when using marijuana products with high THC levels. People have reported symptoms such as anxiety and paranoia, and in rare cases, an extreme psychotic reaction (which can include delusions and hallucinations) that can lead them to seek treatment in an emergency room.

While a psychotic reaction can occur following any method of use, emergency room responders have seen an increasing number of cases involving marijuana edibles. Some people (especially preteens and teens) who know very little about edibles don't realize that it takes longer for the body to feel marijuana’s effects when eaten rather than smoked. So they consume more of the edible, trying to get high faster or thinking they haven't taken enough. In addition, some babies and toddlers have been seriously ill after ingesting marijuana or marijuana edibles left around the house.

Is marijuana addictive?

Marijuana use can lead to the development of a substance use disorder, a medical illness in which the person is unable to stop using even though it's causing health and social problems in their life. Severe substance use disorders are also known as addiction. Research suggests that between 9 and 30 percent of those who use marijuana may develop some degree of marijuana use disorder. 25 People who begin using marijuana before age 18 are four to seven times more likely than adults to develop a marijuana use disorder. 26

Many people who use marijuana long term and are trying to quit report mild withdrawal symptoms that make quitting difficult. These include:

• grouchiness
• sleeplessness
• decreased appetite

What treatments are available for marijuana use disorder?

No medications are currently available to treat marijuana use disorder, but behavioral support has been shown to be effective. Examples include therapy and motivational incentives (providing rewards to patients who remain drug-free). Continuing research may lead to new medications that help ease withdrawal symptoms, block the effects of marijuana, and prevent relapse.

Points to Remember

• Marijuana refers to the dried leaves, flowers, stems, and seeds from the Cannabis sativa or Cannabis indica plant .
• The plant contains the mind-altering chemical THC and other related compounds.
• People use marijuana by smoking, eating, drinking, or inhaling it.
• Smoking and vaping THC-rich extracts from the marijuana plant (a practice called dabbing ) is on the rise.
• altered senses
• impaired memory and learning
• hallucinations and paranoia
• breathing problems
• possible harm to a fetus's brain in pregnant women
• The amount of THC in marijuana has been increasing steadily in recent decades, creating more harmful effects in some people.
• It's unlikely that a person will fail a drug test or get high from passive exposure by inhaling secondhand marijuana smoke.
• There aren’t any reports of teens and adults dying from using marijuana alone, but marijuana use can cause some very uncomfortable side effects, such as anxiety and paranoia and, in rare cases, extreme psychotic reactions.
• Marijuana use can lead to a substance use disorder, which can develop into an addiction in severe cases.
• No medications are currently available to treat marijuana use disorder, but behavioral support can be effective.

For more information about marijuana and marijuana use, visit our:

• Marijuana webpage
• Drugged Driving DrugFacts
• Substance Abuse Center for Behavioral Health Statistics and Quality. Results from the 2018 National Survey on Drug Use and Health: Detailed Tables. SAMHSA. https://www.samhsa.gov/data/report/2018-nsduh-detailed-tables . Accessed December 2019.
• Miech, R. A., Johnston, L. D., Patrick, M. E., O’Malley, P. M., Bachman, J. G., & Schulenberg J. E. (2023). Monitoring the Future National Survey Results on Drug Use, 1975-2022 . Monitoring the Future Monograph Series. Ann Arbor: Institute for Social Research, The University of Michigan.
• Bell C, Slim J, Flaten HK, Lindberg G, Arek W, Monte AA. Butane Hash Oil Burns Associated with Marijuana Liberalization in Colorado. J Med Toxicol Off J Am Coll Med Toxicol. 2015;11(4):422-425. doi:10.1007/s13181-015-0501-0.
• Romanowski KS, Barsun A, Kwan P, et al. Butane Hash Oil Burns: A 7-Year Perspective on a Growing Problem. J Burn Care Res Off Publ Am Burn Assoc. 2017;38(1):e165-e171. doi:10.1097/BCR.0000000000000334.
• Meier MH, Caspi A, Ambler A, et al. Persistent cannabis users show neuropsychological decline from childhood to midlife. Proc Natl Acad Sci U S A. 2012;109(40):E2657-E2664. doi:10.1073/pnas.1206820109.
• Jackson NJ, Isen JD, Khoddam R, et al. Impact of adolescent marijuana use on intelligence: Results from two longitudinal twin studies. Proc Natl Acad Sci U S A. 2016;113(5):E500-E508. doi:10.1073/pnas.1516648113.
• Mehmedic Z, Chandra S, Slade D, et al. Potency trends of Δ9-THC and other cannabinoids in confiscated cannabis preparations from 1993 to 2008. J Forensic Sci. 2010;55(5):1209-1217. doi:10.1111/j.1556-4029.2010.01441.x.
• National Academies of Sciences, Engineering, and Medicine. The Health Effects of Cannabis and Cannabinoids: Current State of Evidence and Recommendations for Research. Washington, DC: The National Academies Press; 2017.
• Young-Wolff KC, Tucker L-Y, Alexeeff S, et al. Trends in Self-reported and Biochemically Tested Marijuana Use Among Pregnant Females in California From 2009-2016. JAMA. 2017;318(24):2490. doi:10.1001/jama.2017.17225
• The National Academies of Sciences, Engineering, and Medicine, Health and Medicine Division, Board on Population Health and Public Health Practice, Committee on the Health Effects of Marijuana: An Evidence Review and Research Agenda. The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research. http://nationalacademies.org/hmd/Reports/2017/health-effects-of-cannabis-and-cannabinoids.aspx . Accessed January 19, 2017.
• Goldschmidt L, Day NL, Richardson GA. Effects of prenatal marijuana exposure on child behavior problems at age 10. Neurotoxicol Teratol. 2000;22(3):325-336.
• Richardson GA, Ryan C, Willford J, Day NL, Goldschmidt L. Prenatal alcohol and marijuana exposure: effects on neuropsychological outcomes at 10 years. Neurotoxicol Teratol. 2002;24(3):309-320.
• Perez-Reyes M, Wall ME. Presence of delta9-tetrahydrocannabinol in human milk. N Engl J Med. 1982;307(13):819-820. doi:10.1056/NEJM198209233071311.
• Galli JA, Sawaya RA, Friedenberg FK. Cannabinoid Hyperemesis Syndrome. Curr Drug Abuse Rev . 2011;4(4):241-249.
• Röhrich J, Schimmel I, Zörntlein S, et al. Concentrations of delta9-tetrahydrocannabinol and 11-nor-9-carboxytetrahydrocannabinol in blood and urine after passive exposure to Cannabis smoke in a coffee shop. J Anal Toxicol. 2010;34(4):196-203.
• Cone EJ, Bigelow GE, Herrmann ES, et al. Non-smoker exposure to secondhand cannabis smoke. I. Urine screening and confirmation results. J Anal Toxicol. 2015;39(1):1-12. doi:10.1093/jat/bku116.
• Herrmann ES, Cone EJ, Mitchell JM, et al. Non-smoker exposure to secondhand cannabis smoke II: Effect of room ventilation on the physiological, subjective, and behavioral/cognitive effects. Drug Alcohol Depend. 2015;151:194-202. doi:10.1016/j.drugalcdep.2015.03.019.
• McCaffrey DF, Pacula RL, Han B, Ellickson P. Marijuana Use and High School Dropout: The Influence of Unobservables. Health Econ. 2010;19(11):1281-1299. doi:10.1002/hec.1561.
• Zwerling C, Ryan J, Orav EJ. The efficacy of preemployment drug screening for marijuana and cocaine in predicting employment outcome. JAMA. 1990;264(20):2639-2643.
• Wang X, Derakhshandeh R, Liu J, et al. One Minute of Marijuana Secondhand Smoke Exposure Substantially Impairs Vascular Endothelial Function. J Am Heart Assoc. 2016;5(8). doi:10.1161/JAHA.116.003858.
• Secades-Villa R, Garcia-Rodríguez O, Jin CJ, Wang S, Blanco C. Probability and predictors of the cannabis gateway effect: a national study. Int J Drug Policy. 2015;26(2):135-142. doi:10.1016/j.drugpo.2014.07.011.
• Levine A, Huang Y, Drisaldi B, et al. Molecular mechanism for a gateway drug: epigenetic changes initiated by nicotine prime gene expression by cocaine. Sci Transl Med. 2011;3(107):107ra109. doi:10.1126/scitranslmed.3003062.
• Panlilio LV, Zanettini C, Barnes C, Solinas M, Goldberg SR. Prior exposure to THC increases the addictive effects of nicotine in rats. Neuropsychopharmacol Off Publ Am Coll Neuropsychopharmacol. 2013;38(7):1198-1208. doi:10.1038/npp.2013.16.
• Cadoni C, Pisanu A, Solinas M, Acquas E, Di Chiara G. Behavioural sensitization after repeated exposure to Delta 9-tetrahydrocannabinol and cross-sensitization with morphine. Psychopharmacology (Berl). 2001;158(3):259-266. doi:10.1007/s002130100875.
• Hasin DS, Saha TD, Kerridge BT, et al. Prevalence of Marijuana Use Disorders in the United States Between 2001-2002 and 2012-2013. JAMA Psychiatry. 2015;72(12):1235-1242. doi:10.1001/jamapsychiatry.2015.1858.
• Winters KC, Lee C-YS. Likelihood of developing an alcohol and cannabis use disorder during youth: association with recent use and age. Drug Alcohol Depend. 2008;92(1-3):239-247. doi:10.1016/j.drugalcdep.2007.08.005.
• Corsi DJ, Walsh L, Weiss D, et al. Association Between Self-reported Prenatal Cannabis Use and Maternal, Perinatal, and Neonatal Outcomes. JAMA . Published online June 18, 2019322(2):145–152. doi:10.1001/jama.2019.8734

This publication is available for your use and may be reproduced in its entirety without permission from NIDA. Citation of the source is appreciated, using the following language: Source: National Institute on Drug Abuse; National Institutes of Health; U.S. Department of Health and Human Services.

November 22, 2004

Marijuana Research

Current restrictions on marijuana research are absurd

By The Editors

The human brain naturally produces and processes compounds closely related to those found in Cannabis sativa , better known as marijuana [see "The Brain's Own Marijuana," by Roger A. Nicoll and Bradley E. Alger. These compounds are called endogenous cannabinoids or endocannabinoids. As the journal Nature Medicine put it in 2003, "the endocannabinoid system has an important role in nearly every paradigm of pain, in memory, in neurodegeneration and in inflammation." The journal goes on to note that cannabinoids' "clinical potential is enormous." That potential may include treatments for pain, nerve injury, the nausea associated with chemotherapy, the wasting related to AIDS and more.

Yet outdated regulations and attitudes thwart legitimate research with marijuana. Indeed, American biomedical researchers can more easily acquire and investigate cocaine. Marijuana is classified as a so-called Schedule 1 drug, alongside LSD and heroin. As such, it is defined as being potentially addictive and having no medical use, which under the circumstances becomes a self-fulfilling prophecy.

Any researcher attempting to study marijuana must obtain it through the National Institute on Drug Abuse (NIDA). The U.S. research crop, grown at a single facility, is regarded as less potent--and therefore less medicinally interesting--than the marijuana often easily available on the street. Thus, the legal supply is a poor vehicle for studying the approximately 60 cannabinoids that might have medical applications.

On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing . By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.

This system has unintended, almost comic, consequences. For example, it has created a market for research marijuana, with "buyers" trading journal co-authorships to "sellers" who already have a marijuana stockpile or license. The government may also have a stake in a certain kind of result. One scientist tells of a research grant application to study marijuana's potential medical benefits. NIDA turned it down. That scientist rewrote the grant to emphasize finding marijuana's negative effects. The study was funded.

Some may argue that researchers do not need to study the drug--after all, there is Marinol, a synthetic version of marijuana's major active compound, tetrahydrocannabinol, or THC; it relieves nausea and stimulates appetite. But patients are often disappointed with Marinol as compared with marijuana. A 1997 editorial in the New England Journal of Medicine noted that "it is difficult to titrate the therapeutic dose of this drug, and it is not widely prescribed. By contrast, smoking marijuana produces a rapid increase in the blood level of the active ingredients and is thus more likely to be therapeutic."

The reasonable course is to make it easier for American researchers to at least examine marijuana for possible medical benefits. Great Britain, no slacker in the war on drugs, takes this approach: the government has authorized a pharmaceutical firm to grow different strains of marijuana for clinical trials.

This call for marijuana research is not a closet campaign for drug legalization--easing research barriers would not require that marijuana be reclassified, nor would it have any bearing on individual states' decisions to approve limited use of medical marijuana. As a 1995 editorial in the Journal of the American Medical Association said, "We are not asking readers for immediate agreement with our affirmation that marijuana is medically useful, but we hope they will do more to encourage open and legal exploration of its potential." After almost a decade of little progress, we reiterate that sentiment.

Read our research on: Gun Policy | International Conflict | Election 2024

Regions & Countries

9 facts about americans and marijuana.

The use and possession of marijuana is illegal under U.S. federal law, but about three-quarters of states have legalized the drug for medical or recreational purposes. The changing legal landscape has coincided with a decades-long rise in public support for legalization, which a majority of Americans now favor.

Here are nine facts about Americans’ views of and experiences with marijuana, based on Pew Research Center surveys and other sources.

As more states legalize marijuana, Pew Research Center looked at Americans’ opinions on legalization and how these views have changed over time.

Data comes from surveys by the Center,  Gallup , and the  2022 National Survey on Drug Use and Health  from the U.S. Substance Abuse and Mental Health Services Administration. Information about the jurisdictions where marijuana is legal at the state level comes from the  National Organization for the Reform of Marijuana Laws .

More information about the Center surveys cited in the analysis, including the questions asked and their methodologies, can be found at the links in the text.

Around nine-in-ten Americans say marijuana should be legal for medical or recreational use,  according to a January 2024 Pew Research Center survey . An overwhelming majority of U.S. adults (88%) say either that marijuana should be legal for medical use only (32%) or that it should be legal for medical  and  recreational use (57%). Just 11% say the drug should not be legal in any form. These views have held relatively steady over the past five years.

Views on marijuana legalization differ widely by age, political party, and race and ethnicity, the January survey shows.

While small shares across demographic groups say marijuana should not be legal at all, those least likely to favor it for both medical and recreational use include:

• Older adults: 31% of adults ages 75 and older support marijuana legalization for medical and recreational purposes, compared with half of those ages 65 to 74, the next youngest age category. By contrast, 71% of adults under 30 support legalization for both uses.
• Republicans and GOP-leaning independents: 42% of Republicans favor legalizing marijuana for both uses, compared with 72% of Democrats and Democratic leaners. Ideological differences exist as well: Within both parties, those who are more conservative are less likely to support legalization.
• Hispanic and Asian Americans: 45% in each group support legalizing the drug for medical and recreational use. Larger shares of Black (65%) and White (59%) adults hold this view.

Support for marijuana legalization has increased dramatically over the last two decades. In addition to asking specifically about medical and recreational use of the drug, both the Center and Gallup have asked Americans about legalizing marijuana use in a general way. Gallup asked this question most recently, in 2023. That year, 70% of adults expressed support for legalization, more than double the share who said they favored it in 2000.

Half of U.S. adults (50.3%) say they have ever used marijuana, according to the 2022 National Survey on Drug Use and Health . That is a smaller share than the 84.1% who say they have ever consumed alcohol and the 64.8% who have ever used tobacco products or vaped nicotine.

While many Americans say they have used marijuana in their lifetime, far fewer are current users, according to the same survey. In 2022, 23.0% of adults said they had used the drug in the past year, while 15.9% said they had used it in the past month.

While many Americans say legalizing recreational marijuana has economic and criminal justice benefits, views on these and other impacts vary, the Center’s January survey shows.

• Economic benefits: About half of adults (52%) say that legalizing recreational marijuana is good for local economies, while 17% say it is bad. Another 29% say it has no impact.

• Criminal justice system fairness: 42% of Americans say legalizing marijuana for recreational use makes the criminal justice system fairer, compared with 18% who say it makes the system less fair. About four-in-ten (38%) say it has no impact.
• Use of other drugs: 27% say this policy decreases the use of other drugs like heroin, fentanyl and cocaine, and 29% say it increases it. But the largest share (42%) say it has no effect on other drug use.
• Community safety: 21% say recreational legalization makes communities safer and 34% say it makes them less safe. Another 44% say it doesn’t impact safety.

Democrats and adults under 50 are more likely than Republicans and those in older age groups to say legalizing marijuana has positive impacts in each of these areas.

Most Americans support easing penalties for people with marijuana convictions, an October 2021 Center survey found . Two-thirds of adults say they favor releasing people from prison who are being held for marijuana-related offenses only, including 41% who strongly favor this. And 61% support removing or expunging marijuana-related offenses from people’s criminal records.

Younger adults, Democrats and Black Americans are especially likely to support these changes. For instance, 74% of Black adults  favor releasing people from prison  who are being held only for marijuana-related offenses, and just as many favor removing or expunging marijuana-related offenses from criminal records.

Twenty-four states and the District of Columbia have legalized small amounts of marijuana for both medical and recreational use as of March 2024,  according to the  National Organization for the Reform of Marijuana Laws  (NORML), an advocacy group that tracks state-level legislation on the issue. Another 14 states have legalized the drug for medical use only.

Of the remaining 12 states, all allow limited access to products such as CBD oil that contain little to no THC – the main psychoactive substance in cannabis. And 26 states overall have at least partially  decriminalized recreational marijuana use , as has the District of Columbia.

In addition to 24 states and D.C.,  the U.S. Virgin Islands ,  Guam  and  the Northern Mariana Islands  have legalized marijuana for medical and recreational use.

More than half of Americans (54%) live in a state where both recreational and medical marijuana are legal, and 74% live in a state where it’s legal either for both purposes or medical use only, according to a February Center analysis of data from the Census Bureau and other outside sources. This analysis looked at state-level legislation in all 50 states and the District of Columbia.

In 2012, Colorado and Washington became the first states to pass legislation legalizing recreational marijuana.

About eight-in-ten Americans (79%) live in a county with at least one cannabis dispensary, according to the February analysis. There are nearly 15,000 marijuana dispensaries nationwide, and 76% are in states (including D.C.) where recreational use is legal. Another 23% are in medical marijuana-only states, and 1% are in states that have made legal allowances for low-percentage THC or CBD-only products.

The states with the largest number of dispensaries include California, Oklahoma, Florida, Colorado and Michigan.

Note: This is an update of a post originally published April 26, 2021, and updated April 13, 2023.  

Sign up for our weekly newsletter

Fresh data delivered Saturday mornings

Americans overwhelmingly say marijuana should be legal for medical or recreational use

Religious americans are less likely to endorse legal marijuana for recreational use, four-in-ten u.s. drug arrests in 2018 were for marijuana offenses – mostly possession, two-thirds of americans support marijuana legalization, most popular.

About Pew Research Center Pew Research Center is a nonpartisan fact tank that informs the public about the issues, attitudes and trends shaping the world. It conducts public opinion polling, demographic research, media content analysis and other empirical social science research. Pew Research Center does not take policy positions. It is a subsidiary of The Pew Charitable Trusts .

Is it dangerous to smoke weed? What you need to know about using marijuana.

Using marijuana at a young age can have lifelong consequences. the drug interferes with the development of the brain..

The push to legalize marijuana at the federal level has gained ground ever since California legalized it for medical use nearly 30 years ago.  Recreational marijuana is now permissible  in 24 states and Washington, D.C. Only four states still outlaw marijuana with no medical exceptions. 

In 2022, President Joe Biden ordered a review of the drug's status as a Schedule I substance, which denotes that a drug has no accepted medical use and has high potential for abuse. If marijuana is reclassified, a renewed push for national legalization will surely follow. 

We aren't here to tell you whether to vote for or against legalizing marijuana. But as a doctor and mental health professional, we're concerned that many Americans may come away from this legalization push with a belief that marijuana is harmless − if not healthful.

That's not quite right, as a growing body of scientific literature shows, including a new landmark study in the Journal of the American Heart Association .

Marijuana can help relieve symptoms of illness

Let's be fair: Marijuana has been shown to alleviate the symptoms and side effects of certain conditions.

Scientific research suggests that the drug can reduce vomiting and nausea in patients undergoing chemotherapy, reduce muscle spasms in patients with multiple sclerosis and provide short-term relief for adults with chronic pain. 

Your quality of life: Do I have to get chemo to treat my cancer? That answer is changing as treatments evolve.

There's some evidence that marijuana might reduce tics in people with Tourette syndrome , increase appetite and reduce weight loss in people with HIV and improve sleep quality for people with sleep apnea. 

But because medical marijuana is federally illegal, there have been relatively few comprehensive and scientifically rigorous studies on its potential benefits. All these areas require further research, including whether benefits actually outweigh risks. 

And let's not get suckered into the cannabis industry's focus on medical utility. For the majority of users, marijuana is a recreational drug that brings pleasure, pure and simple.

Risks of marijuana use include heart attacks and strokes

Unfortunately, that's not all it brings. The risks are real. 

An  American Heart Association study  analyzed data from more than 430,000 adults collected over four years. Researchers found that marijuana use is linked to a significantly higher risk of heart attack and stroke, with the risk increasing with frequency of use. Daily users had a 25% higher chance of heart attack and a 42% higher chance of stroke than non-users. And the increased danger exists whether users smoke, vape or eat their cannabis products. 

It's also important to note that thanks to advances in agricultural technology, the potency of marijuana's psychoactive ingredient – tetrahydrocannabinol, or THC − has dramatically increased. 

Today's marijuana is nothing like the flowers and leaves that filled the joints smoked at Woodstock in 1969. At that time, marijuana contained less than 2% THC. By the '90s, that had doubled to about 4%. Today, THC content in the most popular strains of weed falls between 17% and 28%. Concentrated oils or "dabs," meanwhile, can contain upwards of 95% concentration.

The higher the potency, the greater the risk of addiction − despite the common misconception that marijuana is not addictive.

Not your grandma's weed: Why potency limits must be part of any push to legalize cannabis

A 2014 study from the New England Journal of Medicine showed that nearly 10% of people who try out marijuana get hooked . That figure increases to 17% among those who first try weed in adolescence and to 25% among those who get high every day. 

Marijuana is not a harmless substance, especially for adolescents whose brains have yet to fully develop. Yet teenage marijuana use is also at its highest level  this century. 

Nearly 80% of cannabis users  try the drug for the first time as a teenager . In the years following its legalization in Colorado via a 2012 referendum, marijuana use among 12- to 17-year-olds  increased 65%.

Using marijuana at a young age can have lifelong consequences. The drug interferes with the development of the brain . Impaired attention, problems with memory and difficulty learning are all potential side effects of early exposure to marijuana. 

Studies have shown that  frequent marijuana use can fundamentally alter the brain's prefrontal cortex (our brain's "personality center"), the cerebellum (which controls movement and balance) and the amygdala (which processes emotions and memories).

Recognition of the mental health risks of marijuana use is also growing. A six-year study found that teenage girls are five times more likely to develop depression or anxiety if they smoke weed every day. Because many use marijuana as a coping mechanism for anxiety and depression, they can get themselves into a vicious cycle of dependency and worsening mental health.

Recent research from the National Institutes of Health has linked cannabis use disorder − which afflicts more than 1 in 5 users − to an increased risk of developing schizophrenia.Among men in their 20s, as many as  30% of schizophrenia cases would have been prevented but for marijuana use.

Once people get hooked, marijuana can be incredibly difficult to quit.  Withdrawal symptoms  include depression, insomnia, anger, irritability and, of course, intense cravings to get high again.

Against all this data, it's a dangerous folly to think that getting high poses no health risks. 

At a time when social acceptance of marijuana and access to the drug have skyrocketed, even as youth mental health indicators are plummeting, it's more important than ever to reexamine the notion that weed is harmless. 

Phil McGraw, Ph.D., of daytime TV's "Dr. Phil," is one of the most well-known mental health professionals in the world and founder of Merit Street Media cable network, where he hosts " Dr. Phil Primetime ." Dr. John Whyte is chief medical officer of WebMD .

• Share full article

Advertisement

Supported by

A Conversation With …

Teen Drug Use Habits Are Changing, For the Good. With Caveats.

Dr. Nora Volkow, who leads the National Institutes of Drug Abuse, would like the public to know things are getting better. Mostly.

By Matt Richtel

Historically speaking, it’s not a bad time to be the liver of a teenager. Or the lungs.

Regular use of alcohol, tobacco and drugs among high school students has been on a long downward trend.

In 2023, 46 percent of seniors said that they’d had a drink in the year before being interviewed; that is a precipitous drop from 88 percent in 1979, when the behavior peaked, according to the annual Monitoring the Future survey, a closely watched national poll of youth substance use. A similar downward trend was observed among eighth and 10th graders, and for those three age groups when it came to cigarette smoking. In 2023, just 15 percent of seniors said that they had smoked a cigarette in their life, down from a peak of 76 percent in 1977 .

Illicit drug use among teens has remained low and fairly steady for the past three decades, with some notable declines during the Covid-19 pandemic.

In 2023, 29 percent of high school seniors reported using marijuana in the previous year — down from 37 percent in 2017, and from a peak of 51 percent in 1979.

There are some sobering caveats to the good news. One is that teen overdose deaths have sharply risen, with fentanyl-involved deaths among adolescents doubling from 2019 to 2020 and remaining at that level in the subsequent years.

Dr. Nora Volkow has devoted her career to studying use of drugs and alcohol. She has been the director of the National Institute on Drug Abuse since 2003. She sat down with The New York Times to discuss changing patterns and the reasons behind shifting drug-use trends.

What’s the big picture on teens and drug use?

People don’t really realize that among young people, particularly teenagers, the rate of drug use is at the lowest risk that we have seen in decades. And that’s worth saying, too, for legal alcohol and tobacco.

What do you credit for the change?

One major factor is education and prevention campaigns. Certainly, the prevention campaign for cigarette smoking has been one of the most effective we’ve ever seen.

Some of the policies that were implemented also significantly helped, not just making the legal age for alcohol and tobacco 21 years, but enforcing those laws. Then you stop the progression from drugs that are more accessible, like tobacco and alcohol, to the illicit ones. And teenagers don’t get exposed to advertisements of legal drugs like they did in the past. All of these policies and interventions have had a downstream impact on the use of illicit drugs.

Does social media use among teens play a role?

Absolutely. Social media has shifted the opportunity of being in the physical space with other teenagers. That reduces the likelihood that they will take drugs. And this became dramatically evident when they closed schools because of Covid-19. You saw a big jump downward in the prevalence of use of many substances during the pandemic. That might be because teenagers could not be with one another.

The issue that’s interesting is that despite the fact schools are back, the prevalence of substance use has not gone up to the prepandemic period. It has remained stable or continued to go down. It was a big jump downward, a shift, and some drug use trends continue to slowly go down.

Is there any thought that the stimulation that comes from using a digital device may satisfy some of the same neurochemical experiences of drugs, or provide some of the escapism?

Yes, that’s possible. There has been a shift in the types of reinforcers available to teenagers. It’s not just social media, it’s video gaming, for example. Video gaming can be very reinforcing, and you can produce patterns of compulsive use. So, you are shifting one reinforcer, one way of escaping, with another one. That may be another factor.

Is it too simplistic to see the decline in drug use as a good news story?

If you look at it in an objective way, yes, it’s very good news. Why? Because we know that the earlier you are using these drugs, the greater the risk of becoming addicted to them. It lowers the risk these drugs will interfere with your mental health, your general health, your ability to complete an education and your future job opportunities. That is absolutely good news.

But we don’t want to become complacent.

The supply of drugs is more dangerous, leading to an increase in overdose deaths. We’re not exaggerating. I mean, taking one of these drugs can kill you.

What about vaping? It has been falling, but use is still considerably higher than for cigarettes: In 2021, about a quarter of high school seniors said that they had vaped nicotine in the preceding year . Why would teens resist cigarettes and flock to vaping?

Most of the toxicity associated with tobacco has been ascribed to the burning of the leaf. The burning of that tobacco was responsible for cancer and for most of the other adverse effects, even though nicotine is the addictive element.

What we’ve come to understand is that nicotine vaping has harms of its own, but this has not been as well understood as was the case with tobacco. The other aspect that made vaping so appealing to teenagers was that it was associated with all sorts of flavors — candy flavors. It was not until the F.D.A. made those flavors illegal that vaping became less accessible.

My argument would be there’s no reason we should be exposing teenagers to nicotine. Because nicotine is very, very addictive.

Anything else you want to add?

We also have all of this interest in cannabis and psychedelic drugs. And there’s a lot of interest in the idea that psychedelic drugs may have therapeutic benefits. To prevent these new trends in drug use among teens requires different strategies than those we’ve used for alcohol or nicotine.

For example, we can say that if you take drugs like alcohol or nicotine, that can lead to addiction. That’s supported by extensive research. But warning about addiction for drugs like cannabis and psychedelics may not be as effective.

While cannabis can also be addictive, it’s perhaps less so than nicotine or alcohol, and more research is needed in this area, especially on newer, higher-potency products. Psychedelics don’t usually lead to addiction, but they can produce adverse mental experiences that can put you at risk of psychosis.

Matt Richtel is a health and science reporter for The Times, based in Boulder, Colo. More about Matt Richtel

An official website of the United States government

The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

• Publications
• Account settings

Preview improvements coming to the PMC website in October 2024. Learn More or Try it out now .

• Advanced Search
• Journal List
• HHS Author Manuscripts

Risks and Benefits of Marijuana Use

Current Author Addresses: Drs. Keyhani and Cohen, Ms. Steigerwald, Ms. Vali, Ms. Dollinger, and Ms. Yoo: San Francisco VA Medical Center, 4150 Clement Street, Box 111A1, San Francisco, CA 94121.

Dr. Ishida: San Francisco VA Medical Center, 4150 Clement Street, Box 111J, San Francisco, CA 94121.

Dr. Cerdá: Department of Emergency Medicine, University of California, Davis, 4150 V Street, Suite 2100, Sacramento, CA 95817.

Dr. Hasin: Mailman School of Public Health, Columbia University, 722 West 168th Street, Room 228F, New York, NY 10032.

Author Contributions: Conception and design: S. Keyhani, S. Steigerwald, J. Ishida, M. Cerdá, C. Dollinger, S.R. Yoo. Analysis and interpretation of the data: S. Keyhani, S. Steigerwald, J. Ishida, M. Vali, M. Cerdá, D. Hasin, B.E. Cohen.

Critical revision for important intellectual content: S. Keyhani,S. Steigerwald, J. Ishida, M. Cerdá, D. Hasin, B.E. Cohen. Final approval of the article: S. Keyhani, S. Steigerwald, J. Ishida, M. Vali, M. Cerdá, D. Hasin, C. Dollinger, S.R. Yoo, B.E. Cohen.

Statistical expertise: M. Vali.

Collection and assembly of data: S. Keyhani, S. Steigerwald.

Background:

Despite insufficient evidence regarding its risks and benefits, marijuana is increasingly available and is aggressively marketed to the public.

To understand the public’s views on the risks and benefits of marijuana use.

Probability-based online survey.

United States, 2017.

Participants:

16 280 U.S. adults.

Measurements:

Proportion of U.S. adults who agreed with a statement.

The response rate was 55.3% ( n = 9003). Approximately 14.6% of U.S. adults reported using marijuana in the past year. About 81% of U.S. adults believe marijuana has at least 1 benefit, whereas 17% believe it has no benefit. The most common benefit cited was pain management (66%), followed by treatment of diseases, such as epilepsy and multiple sclerosis (48%), and relief from anxiety, stress, and depression (47%). About 91% of U.S. adults believe marijuana has at least 1 risk, whereas 9% believe it has no risks. The most common risk identified by the public was legal problems (51.8%), followed by addiction (50%) and impaired memory (42%). Among U.S. adults,29.2% agree that smoking marijuana prevents health problems. About 18% believe exposure to secondhand marijuana smoke is somewhat or completely safe for adults, whereas 7.6% indicated that it is somewhat or completely safe for children. Of the respondents, 7.3% agree that marijuana use is somewhat or completely safe during pregnancy. About 22.4% of U.S. adults believe that marijuana is not at all addictive.

Limitation:

Wording of the questions may have affected interpretation.

Conclusion:

Americans’ view of marijuana use is more favorable than existing evidence supports.

M arijuana is legal in 30 states and the District of Columbia for medicinal purposes and in 8 states for recreational use ( 1 ). These legal changes have been accompanied by an increase in daily marijuana use, as well as in marijuana dependence, among adults in the U.S. population ( 2 ). Further, the prevalence of past-year marijuana use in the adult general population doubled in the past decade, reaching 13.3% in 2014 ( 3 ).

With legalization of recreational marijuana, rapid commercialization has ensued. Retail marijuana sales exceed $1 billion annually in Colorado and Washington, the first 2 states to legalize marijuana for recreational purposes ( 4 , 5 ). Extensive media coverage of the business, agricultural, and financial aspects of recreational legalization may be desensitizing the public to safety concerns ( 6 , 7 ). Marijuana is being described on the Internet as a product that may be consumed safely during pregnancy; a product with preventive benefits that improves indices of metabolism, such as glucose and lipid levels; and a potential cure for cancer ( 8 , 9 ).

Whereas the marketing of tobacco and alcohol to consumers is heavily regulated, promotion of marijuana products has no such constraints. Mass marketing of marijuana to the public has not been accompanied by public health messages about the potential risks of these products, because the evidence base describing both benefits and harms is limited ( 10 , 11 ). In the past few years, a substantial effort has been made to identify the risks and benefits of marijuana, as well as the gaps in evidence. Several recent systematic reviews found insufficient evidence to support the use of cannabinoids for treating musculoskeletal pain and low-strength evidence that marijuana use is effective in managing neuropathic pain ( 12 ). A recent meta-analysis concluded that heavy cannabis use increases the risk for psychotic outcomes and that “there is sufficient evidence to justify harm reduction prevention programs” ( 13 ). Although low-strength evidence suggests that marijuana smoking is associated with cough and sputum production, data are insufficient regarding how daily marijuana use might affect long-term physical health, including the effects of frequent or heavy use on cardiovascular outcomes (such as stroke and myocardial infarction), obstructive lung disease, pulmonary function, and cancer ( 14 , 15 ). Available data are also insufficient on the effect of marijuana use among older persons and adults with chronic health conditions ( 12 ). Several studies reported neurocognitive risks with marijuana use, including effects on memory, attention, educational outcomes, and life satisfaction, as well as risk for dependence, but the evidence base is limited and debate continues on whether use in adolescence is associated with an irreversible adverse effect on IQ and cognition ( 16 , 17 ). Emerging data suggest that marijuana may adversely affect treatment of depression and anxiety and that regular marijuana use is associated with emergency department visits and fatal vehicle crashes ( 16 ).

Because of the dearth of data on the adverse consequences of marijuana use and the increasing avail ability of cannabis products, understanding how the public perceives marijuana use is important ( 11 ). National surveys suggest that the perception of “great risk” from weekly marijuana use dropped from 50.4% in 2002 to 33.3% in 2014 ( 3 ). However, we have little understanding of public perceptions of other domains of marijuana use, including specific risks and benefits, potential preventive health benefits, and societal effects (such as exposure to secondhand smoke and driving under the influence). In addition, we have little information on how Americans view marijuana compared with tobacco and alcohol, 2 commonly used substances for which decades of research has created a robust understanding of the potential risks. Finally, no data exist on how perceptions of risks and benefits may vary according to the history of marijuana use.

We conducted a national survey to develop a more comprehensive understanding of the views of U.S. adults toward marijuana use to help public health leaders and state and federal policymakers improve communication regarding risks, benefits, and current gaps in knowledge.

Survey Development

We reviewed existing federal surveys, peer-reviewed literature, and media reports to identify questions used to assess perceived risks and benefits of marijuana use ( 16 , 18 – 20 ). In addition, 2 of the authors (S.K and S.S.) interviewed professionals in various fields, including substance abuse and mental health experts, medical dispensary staff, and marijuana distributors, to understand forms of consumption and potential reasons for marijuana use among the public. On the basis of our review of existing national surveys, our literature review, interviews with professionals in the field, and the investigative team’s experiences (including personal interaction with the public), we drafted survey items that focused on improving our understanding of the general public’s views on marijuana and specifically addressed content areas not covered by federally sponsored surveys. These content areas included perceptions of specific risks and benefits of marijuana use, possible preventive health benefits of different methods of marijuana consumption (smoking, vaping, ingestion), addiction potential, safety of use during pregnancy, and societal effects (including secondhand smoke and driving under the influence). We also developed survey items to compare the perceived safety of marijuana versus alcohol and tobacco. The purpose of these questions was to gauge how Americans view the safety of daily use of marijuana relative to that of commonly used substances with a more established risk profile. The items were motivated partly by the team’s observation (shared by other groups) that marijuana smoking and secondhand exposure to marijuana smoke are common and tolerated in certain areas of California ( 21 ). The survey also included items de signed to capture forms of marijuana use, frequency of use, reasons for use, and knowledge and behaviors associated with use. Overall, 27 questions were designed to capture opinions and 54 to capture use. We designed the survey to include a spectrum of answer options to enable respondents to identify the statement most closely aligned with their beliefs. Because many of the questions did not have clear-cut, scientific answers, we specifically did not include an “I don’t know” option to ensure that respondents chose a statement closest to their current views. Survey items and content were written at an eighth-grade level and tested with online software ( 22 ). Cognitive testing of the items was done with a convenience sample of 40 adults of different ages and education levels, including marijuana users and nonusers, to iteratively refine the content.

Sampling Strategy

To survey U.S. adults, we used Growth from Knowledge (GfK) KnowledgePanel, a probability-based, nationally representative online panel of the civilian, non-institutionalized U.S. population ( 23 ). Growth from Knowledge created KnowledgePanel by randomly sampling addresses. This address-based panel covers 97% of the United States and represents a statistical sample of the country’s population. Households without Web access are provided with an Internet connection and a tablet to ensure participation. All panel members are sampled with a known probability of selection; no one can volunteer to participate. Sampling of participants was stratified by the legalization status (recreational, medical, or nonlegal) of their states to allow comparisons across states. We oversampled 2 groups (California residents and adults aged 18 to 26 years) to support additional research questions. Sampling weights were provided by GfK. Further details on KnowledgePanel’s sampling strategy are provided at www.knowledgenetworks.com/knpanel/docs/knowledgepanel(R)-design-summary-description.pdf .

Survey Administration

The survey was piloted in a random sample of 20 participants to review and refine online administration. The Internet survey was launched on 27 September 2017 to 16 280 U.S. adults aged 18 years and older. Data collection was completed on 9 October 2017. The Committee of Human Subject Research of the University of California, San Francisco, exempted GfK’s conduct of the survey from review.

Statistical Analysis and Weighting

The response rate, determined by using methods outlined by the American Association for Public Opinion Research, was the ratio of respondents to all participants who received the survey ( 24 ). Growth from Knowledge provided final survey weights to account for oversampling of California residents and for nonresponse. Results were weighted by using weights provided by GfK to approximate the U.S. population on the basis of age, sex, race, ethnicity, education level, household income, home ownership, and metropolitan area. Respondents who did not answer all the questions were dropped from the analysis. All analyses used weighting commands based on variables provided by GfK to generate national estimates. To assess how well our sample correlated with federally sponsored surveys, we compared the sociodemographic characteristics of our respondents with those of participants in the 2015 National Survey on Drug Abuse and Health (NSDUH), which provides information on the epidemiology of substance abuse and marijuana use in the United States ( 18 , 20 ). We combined responses to present views as appropriate. The decision to combine results was made at the design stage and was geared toward gauging the direction a respondent was leaning in his or her views. Descriptive statistics were calculated for all items, and results were categorized by time of last marijuana use and age. All analyses were performed with R statistical software, version R-3.4.0 (The R Foundation).

Role of the Funding Source

The funders played no role in the design, conduct, and reporting of the research or in the decision to submit the manuscript for publication.

Response Rate and Participant Characteristics

Overall, 9003 persons responded to the survey, a response rate of 55.3%. The response rate did not vary with regard to legalization status of the state (55.2%, 55.4%, and 55.3%, respectively, for states with recreational, medically legal, and nonlegal status). The rate of missing data or refusal by survey question varied from 0% to 3.9%. Mean age of the sample was 48 years (range, 18 to 94 years). Among the respondents, 52% were women, 64% were white, 12% were black, 16% were Hispanic, and 8% were of other races. Sociodemographic characteristics, including age, sex, race, education level, employment status, and household size, were largely similar to those of NSDUH respondents. Some differences were seen in income level, with KnowledgePanel participants having slightly higher incomes than NSDUH respondents ( Table 1 ).About 14.6% of U.S. adults reported using marijuana in the past year.

Baseline Characteristics of KP Respondents Compared With NSDUH Respondents *

KP = KnowledgePanel; NSDUH = National Survey on Drug Use and Health.

Perceptions of Specific Risks and Benefits

Overall, 81% of U.S. adults believe that marijuana has at least 1 benefit, whereas 17% believe it has no benefit. The benefit most commonly cited by respondents was pain management (65.7%), followed by treatment of dis eases, such as epilepsy and multiple sclerosis (47.9%), and relief from anxiety, stress, and depression (46.8%). When respondents were asked which benefit is most portant, they most commonly endorsed pain management (34.8%), followed by treatment of diseases, such epilepsy and multiple sclerosis (25.2%), and relief stress, anxiety, and depression (11.7%) ( Table 2 ).

Views on Risks and Benefits of Marijuana Use Among U.S. Adults Aged 18 Years or Older, by Past-Year Use *

Overall, 91% of U.S. adults believe marijuana has at least 1 risk, whereas 9% believe it has no risks. The most common risk identified by respondents was legal problems (51.8%), followed by addiction (50%) and impaired memory (42%). When asked about the most important risk, respondents most commonly indicated addiction (21.3%), followed by legal problems (20.7%) and increased use of other drugs (18%).

Overall, more past-year users than nonusers of marijuana agreed with statements indicating that marijuana use has benefits, as well as statements suggesting that marijuana use has no risks. About 1 in 10 marijuana users agreed that addiction is the most important risk associated with marijuana use. Far more nonusers than users agreed that marijuana use has no benefits, and fewer nonusers agreed that marijuana use has no risks.

Preventive Health Benefits

More than a third (36.9%) of U.S. adults strongly or somewhat strongly agree that edible marijuana prevents health problems. More than a quarter (29.2%) strongly or somewhat strongly agree that smoking or vaping marijuana prevents health problems ( Figure 1 ).

Views of U.S. adults aged 18 years or older on whether different forms of marijuana prevent health problems.

Full distribution of responses: Among participants, 7.4% strongly agreed, 29.5% somewhat agreed, 32.7% somewhat disagreed, and 29.2% strongly disagreed that edible marijuana prevents health problems; 5.7% strongly agreed, 23.5% somewhat agreed, 33.9% somewhat disagreed, and 35.7% strongly disagreed that vaping marijuana prevents health problems; and 6.3% strongly agreed, 22.9% somewhat agreed, 30.6% somewhat disagreed, and 39.2% strongly disagreed that smoking marijuana prevents health problems.

Overall, 76% of U.S. adults agree that marijuana is somewhat or very addictive, and 22.4% agree that it is not at all addictive ( Table 3 and Appendix Figure 1 , available at Annals.org ).

Views of Persons in the United States on Important Public Health Domains Pertaining to Marijuana Use *

Among the survey respondents, 92.1% agree that using marijuana during pregnancy is completely or somewhat unsafe. Only 7.3% agree that it is somewhat or completely safe ( Table 3 and Appendix Figure 2 , available at Annals.org ).

Beliefs Toward Secondhand Smoke

About 18% of U.S. adults agree that exposure to secondhand marijuana smoke is safe for adults, and 7.6% agree it is safe for children ( Table 3 and Figure 2 ).

Views among U.S. adults about the safety of secondhand marijuana smoke.

Comparisons Between Marijuana and Other Substances

More than 1 in 3 adults (37.3%) believe that secondhand smoke from marijuana is safer than that from tobacco. More than 1 in 3 (38.2%) agree that smoking 1 marijuana joint a day is much safer or somewhat safer than smoking 1 cigarette a day. About 13.5% agree that smoking 1 marijuana joint per day is safer than drinking 1 glass of wine per day ( Table 3 and Appendix Figure 3 , available at Annals.org ).

The distribution of views on driving under the influence of marijuana is relatively normal. About 27.6% agree that driving under the influence of marijuana is somewhat safer or much safer than driving under the influence of alcohol. About 44.4% agree that driving under the influence of marijuana is as safe as driving under the influence of alcohol, and about 24.7% agree that it is somewhat or much less safe ( Appendix Figure 3 ).

Belief Patterns by Marijuana Use Status and Age

Overall, the rates of agreement with statements suggesting a lack of harm from marijuana use ( Table 3 ) are higher among marijuana users and generally higher among younger adults (aged 18 to 34 years) than in older groups ( Table 3 ).

Most Americans believe that marijuana has both risks and benefits. Although many survey respondents agreed that marijuana may have therapeutic benefits in managing some conditions (such as pain or multiple sclerosis), for which limited evidence of benefit exists, they also believe that marijuana is beneficial in treating insomnia, depression, and anxiety, for which efficacy and safety have not been established and possible harms may exist ( 12 , 25 , 26 ). In addition, a sizable group of survey participants responded that marijuana has no risks or addiction potential and that smoking marijuana prevents health problems.

The survey questions comparing marijuana use with drinking a glass of wine daily provide a useful context in which to evaluate the public’s beliefs. About 13.5% of respondents indicated that daily marijuana smoking is safer than a daily glass of wine. Although excessive alcohol use is associated with many health risks, moderate alcohol intake may prevent coronary heart disease ( 27 , 28 ); however, not enough data exist to support the notion that marijuana use in any form prevents health problems. That 29.2% of U.S. adults strongly or somewhat strongly agree that smoking marijuana prevents health problems is concerning.

The comparisons of daily tobacco versus marijuana use in this study also were informative. Although some investigators reported that marijuana smoking is not detrimental to lung function, the participants in those studies had a low cumulative lifetime exposure and the researchers examined risks in younger cohorts that used marijuana only 2 to 4 times per month over a 20-year follow-up ( 29 , 30 ). More research is needed to inform our understanding of the long-term health effects of daily marijuana smoking. Despite insufficient evidence for potential harms from daily marijuana smoking, media coverage of existing studies with low cumulative exposure may be creating the impression among the public that smoking marijuana, even on a daily basis, is harmless ( 10 ). Likewise, many Americans do not believe that secondhand marijuana smoke is as toxic as secondhand tobacco smoke and believe it is safe to expose adults to secondhand marijuana smoke. Although data on these comparisons are limited or lacking, these views are nonetheless concerning given the evidence that inhalation of particulate matter in any form (for example, breathing smog or secondhand tobacco smoke or smoking) is associated with increased cardiovascular risk ( 31 , 32 ). The public seems to have a more favorable view of marijuana smoking or exposure to secondhand marijuana smoke than is warranted by our current understanding of the detrimental health effects of inhaling particulate matter ( 31 ).

That the American public overall has a favorable view of marijuana use may not be surprising. Several historical trends (including the advocacy for decriminal ization given the societal costs of the war on drugs, evidence that cannabinoids have therapeutic and palliative effects for some intractable conditions ( 12 , 33 ), aggressive marketing of cannabis to the public, and slanted media coverage of marijuana) and ongoing public conversation surrounding legalization of marijuana for recreational use may be sending an overall message that it is safe to use marijuana ( 6 , 7 , 10 , 34 , 35 ). The current, largely state-based regulatory structure to protect consumers is inadequate. The lack of a coherent national policy regulating the sale and promotion of marijuana has left a vacuum that commercial interests can exploit.

This study had several limitations. The survey response rate was 55.3%; however, this rate is similar to that of other national Internet surveys ( 36 – 39 ). Use of an Internet survey might limit generalizability, because persons who choose to join an ongoing Internet panel may differ from those who choose not to. However, studies examining nonresponse to panel recruitment in GfK’s KnowledgePanel found no evidence of nonresponse bias in the panel with regard to core demographic and socioeconomic variables ( 40 ). In addition, although some differences were observed in income distribution between our sample and the NSDUH respondents, the members of both panels were very similar in terms of age, sex, race, education level, household size, and employment status. Finally, we did not conduct reliability testing of the opinion questions, and it is possible that wording of these items introduced bias, which may have affected respondents’ interpretation. Future research should include more psychometric testing of the items to minimize directional bias introduced by the content of the questions.

The gaps in our understanding of the health effects and safety of daily marijuana use are extensive, and the public may be underestimating its long-term risks. These national data underscore the need to invest in further research to better understand both the health effects of marijuana use and the public health investment necessary to better communicate potential health risks to the public.

Acknowledgments

Grant Support: In part by the National Heart, Lung, and Blood Institute of the National Institutes of Health under grant R01HL130484–01A1. Dr. Keyhani’s administrative funds provided by the Northern California Institute for Research and Education also supported this work. Dr. Ishida was supported by career development award K23DK103963 from the National Institute of Diabetes and Digestive and Kidney Diseases.

Reproducible Research Statement: Study protocol: Blank survey tool available from Dr. Keyhani upon request (e-mail, [email protected] ). Statistical code: Not available. Data set: Will be available at https://phprg.ucsf.edu/ before 1 June 2019.

Primary Funding Source: National Heart, Lung, and Blood Institute.

Appendix Figure 1. Responses to the question, “How addictive is marijuana?” among U.S. adults.

Appendix Figure 2. Responses to the question, “How safe is it for pregnant women to use marijuana?” among U.S. adults.

Appendix Figure 3. Views among U.S. adults about driving under the influence of marijuana compared with alcohol, and comparisons of marijuana with tobacco and wine.

Publisher's Disclaimer: Disclaimer: The views expressed in this article are those of the authors and do not represent the views of the U.S. Department of Veterans Affairs or the U.S. government.

Disclosures: Authors have disclosed no conflicts of interest. Forms can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M18-0810 .