Is smoking weed bad for your heart? What the research says about cannabis use and heart health

Smoking cigarettes is known to be one of the biggest risk factors for heart disease . But cannabis use may not be far behind it. Research is showing that frequent cannabis use may have negative consequences for heart health — possibly increasing the risk of major cardiovascular events such as heart attacks or strokes.

While the science is still limited on how exactly cannabis affects the body, here’s what we know so far about what it does to the heart. Cannabis is filled with cannabinoids , or psychoactive chemicals unique to the plant. One cannabinoid, called delta-9-tetrahydrocannabinol, or THC , is what mainly causes the psychoactive effects a person feels when they smoke or ingest the plant.

THC attaches to cannabinoid receptors in the brain, as well as organs and muscle tissue, including the heart and blood vessels. While the smoke from cannabis has negative health effects, especially in the heart and lungs, it’s also emerging that THC itself may have damaging properties — most notably in the heart and vascular system. According to a 2019 study , cannabis use can affect the heart in three major ways: A large 2022 study confirmed some of these earlier findings and found even more evidence of weed’s detrimental effects on heart health.

Here are some of the highlights from this research : Smoking cannabis might be worse for your heart than taking it in other ways, such as through edibles, says Nav Bajaj , MD, a cardiologist at the University of Alabama at Birmingham. This is because smoking cannabis releases compounds such as hydrogen cyanide and nitrogen oxides, which, apart from the cannabinoids, may have additional negative effects on the heart and vascular system, Bajaj says. However, more research is needed to know the effects of all the compounds present in cannabis smoke.

Edible users aren’t entirely off the hook. According to a 2019 study , an edible form of THC was associated with causing a heart attack in one case study. What’s more, edibles can deliver large amounts of THC to the body with a delayed effect, potentially causing more stress on the heart once it enters the bloodstream.

According to the American Lung Association , smoking cannabis has been shown to expose you to the same toxins, irritants, and carcinogens as smoking tobacco. Moreover, when smoking weed users often inhale more deeply than cigarette smokers, and that can lead to more tar exposure. Marijuana smoke in the lungs has been associated with: While Bajaj admits that smoke of all kinds can damage arteries and the heart, there’s simply not enough large-scale studies to see how exactly weed compares to cigarettes on heart health.

Note: For reference, the Centers for Disease Control and Prevention estimate that cigarette smokers are two to four times more likely than non-smokers to develop coronary artery disease . According to a 2019 systematic review , cannabis may lead to a higher risk of heart disease. Out of the 33 studies included, 28 found that cannabis use can increase the risk of chronic cardiovascular disease and acute coronary syndrome , which involves a sudden rupture of plaque inside the coronary artery and may lead to a heart attack.

In addition, Bajaj and his team published a study in 2020 investigating how cannabis affects those with cardiovascular disease. An estimated 2 million people with cardiovascular disease consume cannabis, though Bajaj notes it’s likely that number is underreported. In people with atherosclerotic cardiovascular diseases — or those involving a buildup of plaque in the arteries — cannabis use may increase the risk of harm, according to the study.

When cannabis is smoked or ingested, the sympathetic nervous system is activated, increasing blood pressure and heart rate. According to Bajaj’s study, this nervous system response can increase how much oxygen the heart needs. When combined with factors like plaque buildup in the arteries, this can lead to dangerous heart conditions, including a heart attack .

However, there is still a lot of conflicting research on how cannabis is related to certain cardiovascular diseases — especially heart rhythm disorders. For example, some studies have found that cannabis use is associated with a higher risk of arrhythmias like ventricular tachycardia , ventricular fibrillation, and atrial fibrillation. But others have suggested that cannabis has no effect on ventricular tachycardia or ventricular fibrillation, and that it may even reduce the risk of atrial fibrillation .

In addition, some experts say that cannabis use does not pose a significant threat to people at little risk for heart disease. But another study found that young people who smoke cannabis for more than 10 days a month are 2. 5 times more likely to have a stroke than non-users — even if they don’t use tobacco products.

Right after using cannabis , research has shown that resting heart rate increases and makes the heart pump harder — raising the likelihood of a heart attack. However, a large 2022 study found that people who said they used cannabis five times a month had a lower resting heart rate than those who did not. This could be dangerous because, in some cases, bradycardia — the term for a resting heart rate of less than 60 beats per minute — means that the heart cannot sufficiently pump oxygen-rich blood throughout the body.

Though there’s still a lot we don’t know about weed and cardiovascular health, Bajaj notes where initial data is pointing. “I would say, you know, there is evidence of some harm, but we need to prove that conclusively,” Bajaj says. Research is showing that cannabis use has negative effects on heart health.

Specifically, it can cause inflammation in the heart and blood vessels, as well as platelet aggregation and plaque buildup. In fact, research has found that frequent cannabis users are more likely than nonusers to have a heart attack before age 50. More evidence is also emerging that smoking weed has similar negative effects on the heart and lungs to smoking cigarettes.

And, while THC edibles are less harsh on the lungs, they may still have negative effects on heart health. Overall, more research is needed to get to the bottom of how cannabis affects the heart — but it is clear that it can cause harmful cardiovascular effects. .