A large umbrella review led by the University of Sydney has found no strong evidence that medicinal cannabis effectively treats mental health conditions like anxiety, psychotic disorders, or PTSD.
The analysis included data from 2,477 participants across 54 randomized controlled trials conducted between 1980 and 2025. Researchers found only "relatively weak evidence" of benefit compared to placebo for most conditions.
The review identified just eight trials on psychotic disorders, six on anxiety, and three on PTSD. No eligible trials examined depression. Studies were limited by small sample sizes, short durations, and inconsistent cannabis formulations-some with THC, others with CBD or mixed compounds.
Variability in patient response and challenges in double-blinding due to psychoactive effects further complicate results. Experts stress the need for larger, longer-term, and more targeted clinical trials.
Despite limited evidence, many patients are turning to cannabis due to inadequate responses to standard treatments like antidepressants and cognitive behavioral therapy. However, concerns remain about potential risks, including worsening anxiety or psychosis.
Researchers urge caution and emphasize that current data does not support widespread use of medicinal cannabis for mental health disorders.