Medical cannabis lacks adequate scientific backing for most of the conditions it is commonly used to treat, including chronic pain, anxiety and insomnia, according to a comprehensive review led by UCLA Health.

The paper, published in JAMA, reviewed more than 2,500 articles published from January 2010 through September 2025 including randomized clinical trials, meta-analyses and clinical guidelines. More than 120 studies were prioritized based on their large samples, recency, topics covered and relevancy. The findings come as medical uses for cannabis and cannabinoids such as CBD have grown in popularity, with 27% of people in the U.S. and Canada having reported using it for various purposes such as pain relief, anxiety and sleep problems, according to a 2018 survey.

The review’s first author Dr. Michael Hsu of UCLA Health said there is a gap in understanding between the public and the most recent scientific evidence on its purported medical benefits.

“While many people turn to cannabis seeking relief, our review highlights significant gaps between public perception and scientific evidence regarding its effectiveness for most medical conditions” said Hsu, health sciences clinical assistant professor at the UCLA Health Department of Psychiatry and Biobehavioral Sciences. “Clear guidance from clinicians is essential to support safe, evidence-based decision-making when discussing medical cannabis with their patients.”

The review confirmed that pharmaceutical-grade cannabinoids approved by the U.S. Food and Drug Administration have demonstrated effectiveness but only in a narrow range of conditions. These include medications for HIV/AIDS-related appetite loss, chemotherapy-induced nausea and vomiting and certain severe pediatric seizure disorders such as Dravet syndrome and Lennox-Gastaut syndrome.

For most other conditions, the evidence remains either inconclusive or lacking, the review found. While more than half of people who use medical cannabis report using it for chronic pain, current clinical guidelines recommend against cannabis-based medicines as first-line treatment for chronic pain.

The review also highlighted potential health risks associated with cannabis use. Longitudinal data from adolescents indicated that high-potency cannabis may be linked to increased rates of psychotic symptoms (12.4% versus 7.1% for low-potency) and generalized anxiety disorder (19.1% versus 11.6%).

About 29% of people who use medical cannabis also met criteria for cannabis use disorder. Daily use of cannabis, particularly use of inhaled and/or high-potency products, may be associated with cardiovascular risks, including higher rates of coronary heart disease, heart attack and stroke compared to non-daily use.

The review emphasizes that clinicians should carefully screen patients for cardiovascular disease and psychotic disorders, evaluate potential drug interactions and assess whether the risks outweigh the benefits before considering THC-containing products for medical purposes. 

“Patients deserve honest conversations about what the science does and doesn’t tell us about medical cannabis,” Hsu said. 

The authors noted several limitations of the review. The paper was not a systemic review, and it did not conduct a formal risk of bias assessment of the included studies. Several studies in the review were observational and may be subject to confounding. Additionally, recommendations from clinical trials may not apply to all patients due to variations in their design, patient characteristics and cannabis products tested. 

“Further research is crucial to better understand the potential benefits and risks of medical cannabis. By supporting more rigorous studies, we can provide clearer guidance and improve clinical care for patients,” said Dr. Hsu.

Researchers from Harvard, UC San Francisco, Washington University School of Medicine, and New York University contributed to the study.