Systematic review: medicinal cannabis may offer short-term mental health relief but is not a cure

What the researchers found

High doses of CBD provided some acute relief in anxiety disorders. CBD/THC combinations alleviated withdrawal symptoms in cannabis use disorder and improved sleep. THC was associated with dose-dependent adverse events and, in some psychosis studies, worsened primary outcomes. No study found long-lasting medicinal effects or improvement.

Why it matters

As medicinal cannabis use for mental health grows globally, this review provides the most comprehensive controlled-study assessment to date of what works, what does not, and what carries risks across a wide range of psychiatric diagnoses.

The numbers in context

18,341 studies screened, 49 controlled studies included from 15 countries. Diagnoses covered: anxiety disorders, tic disorders, autism spectrum disorder, ADHD, OCD, anorexia nervosa, schizophrenia/psychosis, substance use disorders, insomnia, and bipolar disorder.

How the study worked

Researchers searched PubMed, PsycInfo, Embase, and Cochrane Library across two search periods (October 2023 and July 2024), screening 18,341 studies. Forty-nine controlled studies from 15 countries were included, covering treatment-seeking participants using medicinal cannabis for their mental health diagnosis.

What this study cannot tell us

Risks of bias were prevalent across included studies. Product compositions, doses, and delivery methods varied widely. Naturalistic and clinical trial findings sometimes contradicted each other. Many diagnoses had very few qualifying studies.

How to read the evidence

Large systematic review of 49 controlled studies across multiple diagnoses and countries, though individual study quality was often limited by bias risks.

When this study was published

Published in 2025, with searches through July 2024.

The bigger picture

The split between product types is critical: CBD appears to help with anxiety, while THC carries risks in psychosis and shows dose-dependent adverse events. Naturalistic studies where participants self-reported THC benefits conflicted with clinical trial findings, highlighting a gap between perceived and measured effects. The absence of any long-term improvement across all studies is a significant finding.

Questions still open

• Why do self-reported benefits of THC in naturalistic studies not translate to clinical trial outcomes? Could longer treatment durations with CBD produce lasting improvements? Is the short-term anxiety relief from CBD clinically meaningful enough to inform treatment guidelines?

Common questions

Read the original research

The differential effects of medicinal cannabis on mental health: A systematic review.

Clinical psychology review, 118, 102581

Citation

de Bode, Nora; Kroon, Emese; Sznitman, Sharon R; Cousijn, Janna. (2025). The differential effects of medicinal cannabis on mental health: A systematic review.. Clinical psychology review, 118, 102581. https://doi.org/10.1016/j.cpr.2025.102581

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