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• Posted December 15, 2025

Large Review Finds Limited Proof Behind Many Medical Cannabis Uses

Medical marijuana is often seen as a safer, natural way to ease pain, anxiety or sleep issues. But a large new review suggests that for many of these uses, the science simply isn’t there.

It adds that a significant share of folks, roughly 30%, using cannabis for medical reasons may actually be at risk for addiction.

The review, published recently in JAMA, examined 15 years of research and found little strong evidence that cannabis helps most of the conditions people commonly use it for.

“The evidence does not support the use of cannabis or cannabinoids at this point for most of the indications that folks are using it for,” lead study author Dr. Michael Hsu, an addiction psychiatrist at UCLA, told The New York Times.

Researchers anazlyzed more than 2,500 clinical trials, medical guidelines and surveys, mostly from the U.S. and Canada. 

Cannabis is legal for medical use in 40 states, fueling a $32 billion industry. But most products sold at dispensaries are not U.S. Food and Drug Administration (FDA)-approved medications. 

A small number of prescription cannabinoids, including Marinol, Syndros and Cesamet, are approved and have shown clear benefits for chemotherapy-related nausea, appetite loss in serious illness and some seizure disorders.

For most other conditions, the evidence isn't as convincing.

Pain is the most common reason people use medical cannabis, yet researchers found no solid evidence that it helps acute pain. Cancer pain guidelines from 2024 also found insufficient evidence to recommend cannabis. 

For chronic, non-cancer pain, some studies showed slight relief with certain THC-heavy products, but no improvement in function, and experts warned against using cannabis as a first-line treatment. 

What's more, inhaling cannabis raises additional risks, including chronic bronchitis and exposure to harmful chemicals, several medical societies noted by the JAMA authors noted.

Sleep is another popular reason people turn to cannabis, but trials again produced weak or inconclusive results. Some people report sleeping worse when they stop using cannabis, which experts say may reflect withdrawal, not benefit.

“If they were to go back to not using cannabis for a month, they might find that their sleep improves," Ryan Vandrey, a professor at Johns Hopkins University in Baltimore, told The Times.

"But most never get to that one month because after a day or two of not sleeping, they convince themselves, ‘Oh, this is the only thing that helps me sleep. So I’ve got to keep using,’ ” he said.

For anxiety, results were mixed. One study of 80 veterans with PTSD found no difference between cannabis and placebo. 

Oral CBD products, such as gummies, showed some benefit in a 2024 study of 316 patients, but experts warned that cannabis can worsen mental illness, including psychosis and suicidal thoughts.

A key concern prompting the review was the growing rate of cannabis use disorder.

A 2024 analysis found that 29% of medical cannabis users had symptoms for the disorder. Another study published earlier this year showed 34% of cannabis users developed symptoms, with higher rates among those using it for medical reasons.

“There are some legitimate purposes for these compounds,” said Dr. Kevin Hill, director of the Division of Addiction Psychiatry at Beth Israel Deaconess Medical Center in Boston. “And there’s a whole other group of people who are saying they’re using it medically, but they’re really not. They’re just rationalizing their recreational use.”

Further, experts say cannabis products today are a lot stronger than in the past, increasing addiction risk.

Unlike prescription drugs, dispensary cannabis is regulated by individual states, not the federal government. Standards for testing and labeling also vary widely, and enforcement is uneven.

As a result, some products may contain mold, pesticides or heavy metals, the review warned.

Even careful customers may not get what they expect, Hsu said, because “because you may not be necessarily getting what you’re hoping for," he told The Times.

Researchers urged doctors to screen patients more carefully for cannabis use, watch for drug interactions and push for stronger clinical trials to ensure cannabis truly helps.

More information

The Mayo Clinic has more on medical marijuana.

SOURCE: The New York Times, Dec. 12, 2025