Many people today are using medical cannabis to help with pain, anxiety, or trouble sleeping. But a large new study led by UCLA Health shows that the science behind these uses may not be as strong as many believe.
The study, published in the journal JAMA, looked at more than 2,500 scientific papers from 2010 to 2025. It focused on the most important 120 studies based on sample size, quality, and relevance.
Cannabis products, including CBD, have become more popular in recent years. A 2018 survey showed that about 27% of adults in the U.S. and Canada had tried cannabis to manage health issues. But according to Dr. Michael Hsu from UCLA Health, there is still a big gap between what people believe about cannabis and what science actually shows.
Dr. Hsu explained that people often think cannabis works well for many conditions, but the scientific proof is limited. He emphasized that doctors need to help patients understand the facts so they can make safe, informed decisions.
The review found that only a few specific cannabis-based medicines have been clearly proven to help. These FDA-approved products are used for serious health problems, such as loss of appetite from HIV/AIDS, nausea caused by chemotherapy, and severe seizure disorders in children, like Dravet syndrome and Lennox-Gastaut syndrome.
For most other medical issues—including the chronic pain that many people use cannabis for—the evidence is still unclear. In fact, current guidelines do not recommend cannabis as the first choice for treating pain.
The review also raised concerns about health risks. Long-term use of high-strength cannabis, especially in teenagers, has been linked to higher rates of psychotic symptoms and anxiety. Around 29% of people who use medical cannabis also meet the criteria for cannabis use disorder, meaning they may be dependent on the drug.
Using cannabis every day—especially strong products or those that are inhaled—may raise the risk of heart problems, including heart attacks and strokes.
Because of these risks, the researchers recommend that doctors screen patients for heart disease and mental health issues before suggesting cannabis. They should also check for other medications that could interact with cannabis.
Doctors need to carefully weigh the possible harms and benefits before recommending products that contain THC, the active ingredient that causes the “high.”
Dr. Hsu said patients deserve open and honest discussions about what science can—and can’t—prove about medical cannabis. He noted that while some people do find relief using cannabis, we need more solid research before doctors can make strong recommendations.
The study had some limitations. It wasn’t a full systematic review, and not all the included studies were high quality. Some of the data came from observational studies, which may not always show cause and effect. Also, clinical trials tested different kinds of cannabis products on different groups of people, so results may not apply to everyone.
Still, the researchers say their findings highlight the need for better studies in the future. With more research, we can better understand how cannabis affects health and give patients clearer advice.
If you care about cannabis, please read studies that what you need to know about cannabis and heart attack, and CBD from cannabis may help inhibit COVID-19 infection.
For more information about cannabis, please see recent studies that medical cannabis could help reduce depression, and results showing this stuff in cannabis may protect aging brain, treat Alzheimer’s.
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