Marijuana Use May Raise Heart Disease Risk by as Much as 23%, Researchers Say

• Early research suggests cannabis use could increase the risk of cardiovascular disease.
• The association appeared regardless of how marijuana was consumed.
• Cardiologists discuss how THC may affect blood vessels and the heart.

As recreational marijuana becomes more widely legal, use has continued to rise. In recent data, about one in six adults said they had used cannabis within the past month, up from one in 10 a few years earlier. That trend has renewed an important question: is marijuana harmless, or could it be affecting our health?

Experts cited in the discussion include Sirisha Vadali, M.D., a board-certified cardiologist, advanced lipidologist, and program director of HonorHealth’s cardiometabolic program, and Travis Benzing, M.D., a cardiologist with Harbor Health.

New findings take a closer look at the issue and raise fresh concerns about what cannabis may be doing to the heart.

The preliminary results, which are set to be presented at the American Heart Association’s Scientific Sessions, found an association between getting high and a higher risk of cardiovascular disease, particularly stroke, regardless of whether marijuana was smoked or eaten. So what does that mean for people who use it occasionally or regularly? Cardiologists break down the findings below.

What did the study find?

The study, which has not yet been peer-reviewed, used survey data from nearly half a million U.S. adults who reported their cannabis use and any heart-related diagnoses from doctors. The information came from the U.S. Behavioral Risk Factor Surveillance System, with participation limited to jurisdictions that collected cannabis-use data over several years.

Compared with nonusers, people who used cannabis one to five days per month had a 23% higher likelihood of reporting cardiovascular disease, while those who used it 16 to 30 days per month had 21% higher odds.

One surprising result was a higher stroke risk among lower-frequency users. Occasional cannabis use was linked to a 40% greater stroke risk than no use, while heavy use was associated with 25% higher odds of stroke. In other words, the study found a more complex relationship than many people might expect.

Still, experts stress that the evidence is limited and more research is needed before firm conclusions can be drawn. Even so, cardiologists say the findings are a useful starting point for conversations about cannabis and heart health.

“This is an early, observational study, so it shows an association, not cause and effect,” says Sirisha Vadali, M.D. “But the signal is consistent with what we’re seeing elsewhere. I’d rather patients know that [possible risk] now than find out after a stroke.”

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How cannabis use may affect heart health

Scientists are still working to understand the connection between cannabis and the heart, but several possible mechanisms have been identified. Much of the concern centers on THC, the main active ingredient in marijuana, rather than the form in which it is consumed.

“Many people assume the risk comes only from the smoke, so switching to edibles feels like the safe option. But THC itself acts on the cardiovascular system,” explains Dr. Vadali. “It binds to cannabinoid receptors in the heart and blood vessels, which can raise your heart rate and cause sudden swings in blood pressure.”

It may also reduce nitric oxide, which helps protect blood vessels by limiting inflammation and slowing the buildup of arterial plaque that can contribute to heart disease over time.

In addition, Dr. Vadali says cannabis may make platelets more likely to clump, increasing the chance of a blockage. In some people, it can also narrow blood vessels or trigger irregular heart rhythms such as atrial fibrillation, which is a known stroke risk.

“THC puts your heart under stress much like a burst of adrenaline,” says Travis Benzing, M.D. “With edibles, people also tend to take more than they planned because the effects take longer to show up,” he adds.

The bottom line

Some people may turn to marijuana instead of alcohol as a way to relax, especially as the heart-related harms of alcohol become more widely recognized. But being plant-based does not automatically make cannabis the safer choice.

“I understand why people see it that way, and I never want patients to feel judged for what they choose. But I’d be careful with the word ‘safer,’” says Dr. Vadali. “Alcohol and cannabis affect the heart in different ways, and the research on cannabis is still catching up. What we’re learning is that it isn’t the harmless option many people assume it is. If you use either one, especially if you have high blood pressure, AFib, or a family history of heart disease, that’s a conversation worth having with your doctor.”

“Be honest with your doctor about cannabis,” says Dr. Benzing. “That’s especially true if you have high blood pressure, diabetes, a family history of heart disease, or a past heart problem. If you’re young and healthy, don’t assume it doesn’t apply to you.”