Smoking weed may make you feel good, but that doesn’t mean marijuana is necessarily beneficial to your physical health. A new scientific statement published in the American Heart Association’s (AHA) journal Circulation warns against using the psychoactive drug because it can potentially harm your heart and blood vessels.

Some chemicals found in cannabis have been linked to a greater risk for heart attacks, heart failure and irregular heartbeat. One study cited suggested that marijuana use was evident in 6% of heart attack patients under age 50, while another reported that weed smokers, between ages 18 and 44, were more likely to suffer a stroke than those who didn’t smoke.

Other research has pointed to tetrahydrocannabinol (THC), the psychoactive ingredient in marijuana, as the main culprit for inducing heart rhythm abnormalities, such as a rapid or irregular heartbeat and an accelerated heart rate in the organ’s ventricles. (THC is also associated with the need for more oxygen in the heart, higher blood pressure while lying down and dysfunction within artery walls.)

But smoking marijuana regardless of the amount of THC it contains has been linked to heart muscle dysfunction, chest pain, heart attacks, heart rhythm disturbances and sudden cardiac death, among other serious cardiovascular conditions.

Researchers believe that how a person consumes cannabis may play a role in its effect on the heart and blood vessels. Smoking and inhaling marijuana can expose people to carbon monoxide intoxication, thus putting them at greater risk for heart problems. In addition, vaping cannabis can have serious health outcomes, including lung injury. 

Also discussed in the AHA statement is cannabidiol (CBD), another common chemical found in marijuana. Some studies found that CBD reduced heart rates, lowered blood pressure, increased the ability of the arteries to open and lowered inflammation. (Inflammation is linked to the slow narrowing of the arteries that underlies most heart attacks and, perhaps, strokes.)

Nevertheless, researchers stressed the need for carefully designed prospective short- and long-term studies regarding cannabis use and cardiovascular safety as the drug becomes increasingly available and more widely used.

“The public needs fact-based, valid scientific information about cannabis’s effect on the heart and blood vessels,” said Robert L. Page II, PharmD, MSPH, chair of the writing group for the statement. “Research funding at federal and state levels must be increased to match the expansion of cannabis use—to clarify the potential therapeutic properties and to help us better understand the cardiovascular and public health implications of frequent cannabis use.”

For related coverage, read “Cannabis May Trigger Harmful Effects in People With Heart Disease.”