Marijuana doubles your risk of cardiovascular death, worrying new study shows

As marijuana has become increasingly mainstream in the United States, researchers are raising concerns about its impact on heart health—adding to a growing list of potential health risks that already include psychosis and schizophrenia.

In a new paper published in the journal Heart, researchers analyzed data from 24 previous studies and found that cannabis use is associated with a significantly increased risk of major cardiovascular events—including “myocardial infarction, a stroke, and increase in cardiovascular death,” says Emilie Jouanjus, a clinical pharmacologist at Centre Hospitalier Universitaire de Toulouse in France and a researcher on the project. 

The findings, based on health data from 200 million people worldwide—including in the United States—showed that cannabis users had a 20 percent higher risk of stroke and twice the risk of death from cardiovascular disease compared to non-users.

That’s a worrying trend in the U.S., where self-reported marijuana use more than doubled since 2008. Even more concerning: cardiovascular disease is already the leading cause of death, responsible for more than 500,000 deaths in the U.S. in 2023.

A wellness product with real risks

Cannabis is widely used for medical purposes, including relief from chemotherapy-induced nausea and management of symptoms from conditions like multiple sclerosis. But “a large part of our population today is thinking that cannabis is a safe natural wellness product, and it’s not,” says Lynn Silver, a senior advisor at the Public Health Institute in California who did not work on the study but did write an accompanying editorial. “It’s not any more [of] a safe natural wellness product than tobacco, which also comes from a plant.”

Vira Pravosud, an assistant research scientist at the San Francisco VA Medical Center who was not involved in the study, adds, “We have this perception that cannabis smoking is healthier, is safer than tobacco smoking, which doesn’t mean that it’s true, just because we don’t know.” 

Researchers aren’t sure of all the ways THC, the psychoactive compound in cannabis, interacts with the cardiovascular system, but emerging evidence shows it may elevate heart rate, raise blood pressure, and trigger inflammation—all of which increase cardiovascular strain. Some studies suggest that THC may also cause blood vessels to constrict, limiting blood flow and potentially increasing the risk of clots or stroke. Inhaling cannabis smoke also exposes users to fine particulate matter, which may contribute to plaque buildup in the arteries and block blood flow.

“If you look at marijuana smoke, at the chemistry of it, it’s not terribly different from tobacco smoke. It’s just that instead of nicotine, you have THC,” says Stanton Glantz, a retired tobacco control and cardiology professor at the University of California, San Francisco (UCSF).

Why research is still playing catch-up

Although recreational marijuana legalization has grown significantly in recent years, cannabis remains a federally classified Schedule I Controlled Substance, complicating research and limiting scientists’ ability to study its long-term effects. That means many cannabis users may feel uncomfortable truthfully reporting use, says Glantz. As a result, the study’s estimates of risk may be conservative.

Other limitations of the study include being unable to differentiate between how cardiovascular risk is associated with different cannabinoid concentrations or between methods of consuming marijuana. Smoke inhalation, whether as a method of consuming substances, secondhand, or from wildfires, has been associated with increased cardiovascular risk. 

But “there’s some recent research from UCSF that also suggests that cannabis users who use edibles have some basic physiological changes that are associated with heart disease risk,” Silver says. “So it seems pretty clear that smoking is associated. What we can’t say is that you’re safe using edibles, for example.”

Several of the analyzed studies also showed that cardiovascular risk increased with heavier cannabis use, suggesting more frequent consumers may be more at risk. Some researchers suspect that older adults or those with pre-existing heart conditions may be especially vulnerable, though further research is needed.

Still, despite the study’s limitations and unanswered questions, researchers feel strongly that cardiovascular health should be considered before deciding to consume cannabis products. “There is no doubt there is an increase [in cardiovascular risk],” Jouanjus says. “It may not be clinically significant [yet], but [with the] high probability of under-reporting… I think that it’s still important to say that the risk exists.”