Bold claim: Most medical uses of cannabis lack solid scientific support. A comprehensive UCLA Health–led review finds that for many conditions, including chronic pain, anxiety, and insomnia, the evidence base is insufficient or inconclusive. The study, published in JAMA, examined over 2,500 articles published between January 2010 and September 2025, focusing on randomized trials, meta-analyses, and clinical guidelines. Out of these, more than 120 studies were prioritized for their large sample sizes, recency, topic relevance, and applicability. This comes as cannabis and cannabinoids like CBD become increasingly popular, with about 27% of people in the U.S. and Canada reporting use for pain relief, anxiety, or sleep issues according to a 2018 survey.
Lead author Dr. Michael Hsu of UCLA Health notes a gap between public perception and the latest scientific evidence surrounding medical cannabis. He emphasizes the need for clinicians to provide clear, evidence-based guidance to help patients make safe, informed decisions about medical cannabis use.
The review confirms that FDA-approved pharmaceutical cannabinoids show effectiveness, but only for a narrow set of conditions. These include therapies addressing HIV/AIDS-related appetite loss, chemotherapy-induced nausea and vomiting, and some severe pediatric seizure disorders such as Dravet syndrome and Lennox-Gastaut syndrome.
For most other conditions, evidence remains unclear or lacking. Although more than half of medical cannabis users report using it for chronic pain, current clinical guidelines do not endorse cannabis-based medicines as a first-line option for chronic pain management.
The review also highlights potential health risks. Data tracking adolescents suggest that high-potency cannabis use may be associated with higher rates of psychotic symptoms (12.4% vs. 7.1% with low potency) and generalized anxiety disorder (19.1% vs. 11.6%). About 29% of medical cannabis users meet criteria for cannabis use disorder. Daily use, especially inhaled or high-potency products, may be linked to cardiovascular risks such as higher rates of coronary heart disease, heart attack, and stroke compared with non-daily use.
Clinicians are urged to screen for cardiovascular disease and psychotic disorders, review possible drug interactions, and weigh risks against benefits before considering THC-containing products for medical purposes. Dr. Hsu states that patients deserve candid conversations about what science does and does not show regarding medical cannabis.
The authors acknowledge several limitations: the review was not a systematic review and did not include a formal risk-of-bias assessment. Some studies were observational and could be affected by confounding factors. Additionally, trial designs, patient characteristics, and product formulations vary, which may affect applicability to individual patients.
The authors call for more rigorous research to clarify potential benefits and risks and to inform clinical care. Contributions came from researchers at Harvard, UC San Francisco, Washington University School of Medicine, and New York University.
