A new study from UC San Francisco warns that both smoking and eating cannabis may pose serious long-term risks to heart health.

Published in JAMA Cardiology, the study followed 55 healthy adults aged 18–50, divided into three groups: cannabis smokers, edible users, and non-users. Many had used cannabis for five to ten years. Tests revealed those who consumed cannabis—regardless of method—had significantly reduced blood vessel function.

Researchers found that cannabis users had “decreased vascular function” similar to tobacco smokers. Blood flow was nearly half that of non-users, increasing the risk of high blood pressure, heart attacks, and other cardiovascular diseases.

Even edibles showed the same vascular risks as smoking, though the underlying mechanisms differed. One expert, Dr. Bradley Serwer, noted the results weren’t surprising, adding that “chronic THC use can have negative health consequences.”

While cannabis is often viewed as a natural, safe option, this study highlights that its long-term use may not be as harmless as many think. Researchers stress: “Cannabis use is not benign.”