Can Cannabis Treat Mental Health Conditions? The Evidence
What Researchers Found About Anxiety and Cannabis
The Study at a Glance
Published
Lancet Psychiatry, 2019
Researchers
University of New South Wales (Australia)
Study Type
Meta-AnalysisParticipants
3,067 patients · Various
Key Finding
This comprehensive Lancet Psychiatry analysis of 83 studies found scarce evidence that cannabis helps mental health conditions. The only modest benefit was for anxiety in people already using cannabis for other conditions like chronic pain—and even this evidence was very low quality.
Key Finding: This comprehensive Lancet Psychiatry analysis of 83 studies found scarce evidence that cannabis helps mental health conditions. The only modest benefit was for anxiety in people already using cannabis for other conditions like chronic pain—and even this evidence was very low quality.
What Researchers Studied About Anxiety and Cannabis
Cannabis is increasingly promoted for anxiety, depression, PTSD, and other mental health conditions. But does the scientific evidence actually support these claims?
This landmark 2019 analysis in Lancet Psychiatry examined ALL available evidence on cannabinoids for mental disorders—including depression, anxiety, PTSD, ADHD, Tourette syndrome, and psychosis.
With mental health conditions affecting millions and cannabis laws changing rapidly, researchers needed to separate hype from evidence.
How This Meta-Analysis Was Conducted
Researchers conducted a comprehensive systematic review and meta-analysis:
• Searched multiple databases from 1980 to 2018 • Included 83 studies (40 randomized controlled trials) • 3,067 total participants across all studies • Examined depression, anxiety, PTSD, ADHD, Tourette syndrome, and psychosis • Assessed both pharmaceutical cannabinoids and medicinal cannabis • Rated evidence quality using GRADE methodology
Anxiety Treatment Results
The Main Results:
- 1No significant evidence that cannabinoids help depression
- 2Very low quality evidence for small anxiety improvement (only in those with other conditions)
- 3No evidence of benefit for PTSD (only 1 RCT with 10 participants)
- 4No evidence of benefit for ADHD or Tourette syndrome
- 5THC worsened negative symptoms of psychosis
- 6Doubled risk of adverse events; nearly tripled withdrawal due to adverse events
By the Numbers
| Statistic | What It Means |
|---|---|
| 83 | studies analyzed (40 randomized controlled trials) |
| 3,067 | participants across all studies |
| 2x | increased risk of adverse events with cannabinoids |
| 2.8x | increased withdrawal due to adverse events |
studies analyzed (40 randomized controlled trials)
participants across all studies
increased risk of adverse events with cannabinoids
increased withdrawal due to adverse events
What This Means for Anxiety Patients
This rigorous Lancet Psychiatry review delivers an important reality check:
What the evidence shows: • Depression: No evidence cannabinoids help • Anxiety: Very weak evidence of small benefit—but only in people using cannabis for other conditions • PTSD: Insufficient evidence (only 1 tiny study) • ADHD: No evidence of benefit • Tourette syndrome: No evidence of benefit • Psychosis: THC may worsen symptoms
The side effect reality: • Doubled risk of adverse events • Nearly tripled risk of stopping due to side effects
What this means for you: If you're considering cannabis specifically to treat a mental health condition, this evidence does NOT support that decision. The authors explicitly state there is "insufficient evidence to provide guidance on the use of cannabinoids for treating mental disorders."
Important distinction: Some people report cannabis helps their anxiety or mood—but the controlled research doesn't support using cannabinoids as a primary treatment for mental disorders. If cannabis helps your anxiety while you're using it for chronic pain, that's different from using it to treat an anxiety disorder.
Quick Answers: Anxiety and Cannabis
Direct answers based on the findings of this study:
Research Summary: Answers are based on published peer-reviewed studies and represent research findings, not medical recommendations. Individual results may vary. Always consult a healthcare provider before making treatment decisions.
Does weed help depression?
No—a major Lancet Psychiatry review of 42 studies found no evidence that cannabis improves depression. Don't rely on marijuana to treat depression; talk to a mental health professional about proven treatments.
Source: Black et al., Lancet Psychiatry, 2019 (PMID: 31672337)
Can marijuana treat anxiety disorders?
Evidence is very weak. Lancet Psychiatry found only "very low quality" evidence of small benefit—and only in people using cannabis for other conditions, not primary anxiety. Cannabis isn't a proven anxiety treatment.
Source: Black et al., Lancet Psychiatry, 2019 (PMID: 31672337)
Is marijuana good for mental health?
No strong evidence supports this. A Lancet Psychiatry analysis of 83 studies found "scarce evidence" cannabis helps depression, anxiety, ADHD, PTSD, or other mental disorders. THC actually worsened psychosis symptoms.
Source: Black et al., Lancet Psychiatry, 2019 (PMID: 31672337)
This is educational content, not medical advice
The research summarized here is for informational purposes only. Individual results may vary, and what works in studies may not work the same way for everyone. Always consult with a qualified healthcare provider before making changes to your treatment plan or starting medical cannabis therapy.
Important Limitations
This study has some caveats to keep in mind when interpreting the results:
- Many studies were small and short-term
- Very few studies on CBD alone or medicinal cannabis
- PTSD had only one RCT with 10 participants
- Studies often excluded people with severe mental illness
- Different cannabis preparations make comparisons difficult
The Bottom Line on Cannabis for Anxiety
This comprehensive Lancet Psychiatry analysis delivers a sobering message: despite popular claims, there is "scarce evidence" that cannabis treats mental health conditions. The only hint of benefit was for anxiety in people already using cannabis for other conditions—and even that evidence was very low quality. If you have depression, PTSD, or anxiety, cannabis should not be your primary treatment. Talk to a mental health professional about evidence-based treatments first.
Do You Qualify for Medical Marijuana?
If you're living with Anxiety, you may qualify for a medical marijuana card. Our licensed physicians can evaluate you from home via telehealth.
Related Research & Resources
Related Research
Condition Research
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This condition qualifies for medical marijuana in:
Source
Black N, Stockings E, Campbell G, et al. "Cannabinoids for the treatment of mental disorders and symptoms of mental disorders: a systematic review and meta-analysis" Lancet Psychiatry. 2019. DOI: 10.1016/S2215-0366(19)30401-8
Important Information
Study Age: This study was published 7 years ago. Newer research may have updated or refined these findings.
Not Medical Advice: This research summary is for educational purposes only. It should not be used to diagnose, treat, cure, or prevent any disease or medical condition. Always consult a qualified healthcare provider before starting or changing any treatment.
Individual Variation: Research findings represent group averages. Your individual response to cannabis may differ based on genetics, other medications, underlying conditions, and many other factors.
Last reviewed: January 24, 2026
Important Notices
Research Summary Disclaimer
This content represents our interpretation of published scientific research for educational purposes. It should not be used to make treatment decisions without consulting a qualified healthcare provider. Individual results may vary from study findings.
FDA Notice
These statements have not been evaluated by the FDA. Cannabis is not intended to diagnose, treat, cure, or prevent any disease. The FDA has not approved cannabis for any medical condition except specific prescription medications.
Copyright & Fair Use
Research summaries are provided under fair use (17 U.S.C. § 107) for educational purposes. We provide brief summaries with attribution, not full reproductions. All studies remain the intellectual property of their respective authors and publishers.
Data Sources
Study information sourced from PubMed®, U.S. National Library of Medicine. Inclusion does not imply endorsement by NLM, NIH, or the federal government.
For complete information, see our Terms of Use and Research Content Policy.
FAQs: Cannabis for Anxiety
Does cannabis help depression?
No, evidence does not support this. A comprehensive 2019 Lancet Psychiatry review of 42 studies found no significant evidence that cannabinoids improve depression symptoms.
Does cannabis help anxiety?
Evidence is very weak. The review found only "very low quality evidence" for a small improvement in anxiety, and only in people already using cannabis for other conditions, not for primary anxiety disorders.
Should I use cannabis for PTSD?
Not yet supported by evidence. The Lancet review found only one small trial (10 participants) for PTSD. While some veterans report benefit, high-quality evidence is lacking. Talk to a mental health professional about proven PTSD treatments.