Scientists reveal the real benefits and hidden risks of medical cannabis

A study published in JAMA examined more than 2,500 scientific papers released from January 2010 through September 2025, including randomized clinical trials, meta-analyses and clinical guidelines. Over 120 of these studies were given priority based on sample size, recency, relevance and the range of health conditions they addressed. Interest in cannabis and related compounds such as CBD has steadily increased, and a 2018 survey found that 27% of adults in the U.S. and Canada had used them for concerns like pain, anxiety and sleep.

Public Belief Outpaces Current Scientific Evidence

According to first author Dr. Michael Hsu of UCLA Health, many people assume cannabis provides reliable medical benefits, yet recent research does not fully support those assumptions.

“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.”

Proven Benefits Remain Narrow

The review found that only specific pharmaceutical-grade cannabinoid products approved by the U.S. Food and Drug Administration have demonstrated clear clinical benefits. These medications are limited to certain conditions, including HIV/AIDS-related appetite loss, chemotherapy-induced nausea and vomiting and severe pediatric seizure disorders such as Dravet syndrome and Lennox-Gastaut syndrome.

For many other health problems, the available evidence remains uncertain or insufficient. Although more than half of medical cannabis users try it for chronic pain, current clinical guidelines do not recommend cannabis-based treatments as the first option for pain management.

Potential Health Risks Identified

The analysis also examined safety concerns. Long-term studies in adolescents showed that high-potency cannabis may be associated with higher rates of psychotic symptoms (12.4% versus 7.1% for low-potency) and generalized anxiety disorder (19.1% versus 11.6%).

Around 29% of medical cannabis users also met the criteria for cannabis use disorder. Daily consumption, especially of inhaled or high-potency products, may contribute to cardiovascular problems, including elevated risks of coronary heart disease, heart attack and stroke when compared with non-daily use.

Guidance for Clinicians

The review recommends that clinicians screen for cardiovascular disease and psychotic disorders, consider possible drug interactions and evaluate whether potential harms outweigh the benefits before recommending THC-containing products.

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

Study Limitations and the Need for More Research

The authors acknowledged several limitations. The analysis was not a systemic review, and no formal risk of bias assessment was completed. Some of the research included was observational and may have been influenced by confounding factors. Clinical trial findings may also not apply to every patient due to differences in study design, participant characteristics and the cannabis products evaluated.

“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.