Medicinal cannabis is increasingly used to treat a variety of conditions, but a comprehensive new review suggests that there is insufficient scientific evidence to support its effectiveness in many cases. Other scientists, however, have questioned the quality of the study's findings.
Researchers in the US analyzed 124 studies, whittled down from more than 2,500 papers published between January 2010 and September 2025.
Their review reaffirmed that medicinal cannabis seems to be an effective treatment for a few conditions for which the FDA has already approved its use. That includes reducing nausea and vomiting from chemotherapy, improving appetite in patients with HIV, and treating some severe seizure disorders in children.
But according to the study, this was the exception, rather than the rule.
"Evidence from randomized clinical trials does not support the use of cannabis or cannabinoids for most conditions for which it is promoted, such as acute pain and insomnia," the authors write.
Related: Largest Study Yet on Cannabis And Brain Function Finds a Worrying Link
The review also notes potential health problems with frequent inhaled or high-potency cannabis use, including increased risks of psychotic symptoms, generalized anxiety disorder, and cardiovascular disease.
"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," says first author Michael Hsu, clinical researcher at the University of California, Los Angeles.
However, not all scientists agree with the review's conclusions.
"The methodology lacks clarity about why certain studies were included, whilst others examining similar outcomes may have been excluded," Simon Erridge, Director of Research at Curaleaf Clinic, a medical cannabis clinic in the UK, told journalist Sarah Sinclair at Cannabis Health.
"There appears to be a tendency in the JAMA review to emphasize negative outcomes whilst giving less prominence to research suggesting therapeutic benefits."
Among the review's limitations, Hsu and his co-authors acknowledge that "some relevant articles may have been missed."
They also note that it wasn't a systematic review, and a formal risk of bias assessment wasn't conducted for the individual studies, many of which were observational.
A 2023 review of similar studies reached some of the same conclusions, although it found evidence that medicinal cannabis could be effective in relieving chronic pain, but not without adverse events.
"Further research is crucial to better understand the potential benefits and risks of medical cannabis," says Hsu.
"By supporting more rigorous studies, we can provide clearer guidance and improve clinical care for patients."
The research was published in The Journal of the American Medical Association.