Largest Global Review Finds No Evidence That Medicinal Cannabis Effectively Treats Anxiety, Depression, or PTSD

The largest-ever review of medicinal cannabis, published in The Lancet Psychiatry, finds no evidence that it helps with anxiety, depression, or PTSD.

By: AXL Media

Published: Mar 17, 2026, 5:35 AM EDT

Source: Information for this report was sourced from University of Sydney

A Critical Re-Evaluation of Cannabinoid Efficacy

The rapid global expansion of medicinal cannabis prescriptions has hit a significant scientific hurdle following the release of the largest-ever review of its safety and efficacy. Published in The Lancet Psychiatry, the landmark study conducted by researchers at the University of Sydney found no evidence that medicinal cannabis is effective in treating depression, anxiety, or post-traumatic stress disorder. Despite more than one million prescription approvals in Australia alone over the last four years, the data suggests that the clinical reality of these medications does not match their widespread use. Lead author Dr. Jack Wilson notes that these findings call into question the current regulatory approval of cannabinoids for a broad range of psychiatric conditions.

Potential Risks and the Delay of Effective Care

While the study focused on efficacy, researchers expressed significant concern regarding the secondary harms of routine medicinal cannabis use. There is a growing risk that such treatments may actually worsen mental health outcomes by increasing the likelihood of psychotic symptoms or leading to the development of cannabis use disorder. Furthermore, according to Dr. Wilson, the reliance on ineffective cannabinoid products can lead to a dangerous delay in patients seeking more established, evidence-based treatments. This "treatment gap" poses a serious threat to individuals with severe mental health conditions who may be opting for medicinal cannabis over more effective pharmaceutical or psychological interventions.

Limited Benefits Observed in Non-Psychiatric Conditions

The meta-analysis did identify a handful of conditions where medicinal cannabis might offer some level of symptomatic relief, though often backed by low-quality evidence. The study suggested potential benefits for insomnia, tics, Tourette’s syndrome, and autism, but researchers urged extreme caution regarding these findings. In the specific case of autism, the diverse nature of the condition means that a "universal" medicinal experience is unlikely. However, more robust evidence remains for the use of cannabis-derived medications in treating specific types of epilepsy, spasticity in multiple sclerosis patients, and certain categories of chronic pain, though these fell outside the primary focus on mental health disorders.