Cannabinoids Show Limited Benefits in substance use, mental disorders with Increased Adverse Events: Study

A systematic review and meta-analysis published in journal of The Lancet Psychiatry suggests that cannabinoids may help reduce symptoms of certain substance use disorders (SUDs) and mental disorders, though the overall quality of evidence is low. Moderate-certainty evidence supports improved sleep duration in insomnia.

This research spanned from 1980 to May 2025 combing through major medical databases, and evaluated whether cannabinoid-based treatments like cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC), are effective and safe when used as primary therapies for psychiatric disorders and addictions.

In total, 54 clinical trials involving 2,477 participants were included. However, nearly half of these studies were found to carry a high risk of bias, and the overall quality of evidence was rated as low for most outcomes.

For individuals with cannabis use disorder, combined CBD and THC treatments appeared to reduce withdrawal symptoms and lower weekly cannabis consumption. The patients with Tourette’s syndrome or tic disorders experienced reductions in tic severity. Cannabinoids were also associated with improved sleep duration in individuals with insomnia and showed small reductions in autistic traits among those with autism spectrum disorder.

Cannabinoids showed no meaningful effect in treating several major psychiatric conditions, including anxiety disorders, post-traumatic stress disorder (PTSD), psychotic disorders, anorexia nervosa, and opioid use disorder. There was complete absence of randomized trial evidence supporting their use for depression.

The participants using cannabinoids were significantly more likely to experience adverse events when compared to those receiving a placebo, with one additional harmful outcome occurring for roughly every seven patients treated. While these side effects were not typically classified as serious, the increased risk raises concerns about widespread clinical use.

In some cases, cannabinoids may even worsen outcomes, where individuals with cocaine use disorder reported increased cravings when treated with cannabinoids, which highlighted the complexity of their effects on the brain.

While cannabinoids may hold potential for select conditions, current evidence does not support their routine use in most mental health or substance use disorders. They emphasize the need for larger, high-quality trials to better understand both the benefits and risks.

Reference:

Wilson, J., Dobson, O., Langcake, A., Mishra, P., Bryant, Z., Leung, J., Dawson, D., Graham, M., Teesson, M., Freeman, T. P., Hall, W., Chan, G. C. K., & Stockings, E. (2026). The efficacy and safety of cannabinoids for the treatment of mental disorders and substance use disorders: a systematic review and meta-analysis. The Lancet. Psychiatry, 13(4), 304–315. https://doi.org/10.1016/S2215-0366(26)00015-5