Major Lancet Review Finds Little Mental‑Health Benefit From Medicinal Cannabis

A University of Sydney team has published a large meta‑analysis in The Lancet Psychiatry reviewing 54 randomized controlled trials from 1980 to 2025, involving 2,477 participants, and finds little strong evidence that medicinal cannabinoids effectively treat most mental disorders or substance‑use disorders. The authors report that despite cannabis products being widely prescribed in the U.S., U.K. and Australia for depression, anxiety and PTSD, there is no convincing evidence they help those conditions, and that cannabinoid treatments raised the risk of adverse side effects by about 75%. Limited, low‑quality signals of benefit were seen for issues such as cannabis use disorder, insomnia, Tourette’s symptoms and some autistic traits, but no significant benefit emerged for anxiety disorders, psychotic disorders, PTSD, opioid use disorder or anorexia nervosa, and no qualifying randomized trials for depression were found. Lead author Dr. Jack Wilson warned that routine medical‑cannabis use for mental health may be doing 'more harm than good' by worsening outcomes or delaying effective care, a message echoed by NYU psychiatrist Dr. Thea Gallagher, who said the new review is the most comprehensive to date and undercuts widespread assumptions on social media that cannabis is a proven treatment for emotional distress. The paper distinguishes this from established uses of certain cannabis‑based products in epilepsy, multiple sclerosis and some pain conditions, underscoring that evidence for psychiatric indications has not caught up with rapidly expanding medical‑marijuana laws and marketing in the U.S.