Studies show that medical cannabis does not help as much as people think

The review, published in the medical journal JAMA, included an analysis of more than 2,500 studies published between January 2010 and September 2025. The researchers looked at randomized intervention studies, meta-analyses, clinical guidelines and observational studies. Of these, more than 120 key studies were selected according to sample size, recency, clinical relevance and the variety of medical conditions examined. The data indicate a clear trend, the medical use of cannabis is expanding rapidly, but the scientific knowledge supporting it is advancing at a much slower pace.

According to the data, use of cannabis and its components, including CBD, is particularly common in North America. A 2018 survey showed that 27% of adults in the US and Canada used cannabis for medical purposes, mainly to relieve pain, anxiety and sleep disorders. However, the researchers emphasize that the evidence supporting the effectiveness of cannabis for these conditions is weak, inconsistent and sometimes contradictory.

The review shows that the clearest and most established benefits have only been found in specific drug-grade cannabinoid preparations approved by the US Food and Drug Administration. These preparations have been proven to be effective in specific situations, including loss of appetite among HIV and AIDS patients, nausea and vomiting due to chemotherapy, and severe epileptic syndromes in children such as Dravet and Lennox Gastaut. Beyond these situations, most of the common uses are not supported by clinical recommendations as a first line of treatment.

In the field of chronic pain, one of the most common uses of medical cannabis, the researchers state that the evidence does not justify a blanket recommendation. Although more than half of the users report use for this purpose, the existing clinical guidelines do not consider cannabis a preferred treatment, and sometimes even warn against uncontrolled use.

At the same time as examining the efficiency, special attention was also given to safety. Analysis of long-term studies among adolescents revealed a link between the use of high-potency cannabis and a higher rate of psychotic symptoms and general anxiety, compared to the use of low-potency strains. It was also found that approximately 29% of medical cannabis users meet the criteria for a cannabis use disorder.

The study also points to possible cardiovascular risks. Daily use, especially of inhaled products or products with a high concentration of THC, has been linked to an increased risk of coronary heart disease, heart attack and stroke, compared to people who do not use regularly.

In light of the findings, the researchers recommend that doctors perform an orderly screening for heart disease and psychotic disorders before recommending cannabis, examine possible drug interactions and evaluate individually if the expected benefit outweighs the risk. Dr. Hsu emphasized that patients are entitled to honest and data-based discourse on what science knows and what has not yet been proven in the field of medical cannabis.

The researchers also point out limitations to the study, including the fact that it is not a complete systematic review and the lack of a formal bias assessment. Some of the studies were observational, and therefore exposed to intervening factors. On the other hand, they emphasize that the scope of the data allows for a relatively broad picture of the situation, and illustrates the need for more controlled and high-quality studies in the future.