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A new study finds using cannabis daily can significantly increase your heart disease risk. Alberto Case/Getty Images
  • Using cannabis is associated with an increased risk of heart attack and stroke, independent of tobacco use, a study of 430,000 adults found.
  • People who used cannabis more frequently had a higher risk, but the risk was present even in people who used cannabis less than daily.
  • The cardiovascular risks were even present in cannabis users who had never used tobacco cigarettes or nicotine e-cigarettes.

Cannabis use may increase the risk of heart attack and stroke, a new study of over 430,000 U.S. adults found. This association was present even after researchers took into account tobacco use and other risk factors for cardiovascular disease.

Over 48 million Americans reported using cannabis at least once in 2019, with three in 10 people who use cannabis having cannabis use disorder, according to the Centers for Disease Control and Prevention.

Although cannabis remains illegal at the federal level, 24 states and the District of Columbia have legalized it for recreational use, with additional states allowing medical use of cannabis, aka marijuana.

This has led to an increase in the use of cannabis among adults over the past decade, even as cigarette smoking rates have dropped since the 1960s.

“Despite common use, little is known about the risks of cannabis use and, in particular, the cardiovascular disease risks,” study author Abra Jeffers, PhD, a data analyst at Massachusetts General Hospital in Boston, said in a statement.

“However, previous research suggested that cannabis could be associated with cardiovascular disease,” she said. “In addition, smoking cannabis — the predominant method of use — may pose additional risks because particulate matter is inhaled.”

In the study, published February 28 in the Journal of the American Heart Association, Jeffers and her colleagues reviewed data on 434,104 adults from 2016 to 2020 to examine the link between cannabis use and adverse cardiovascular outcomes (heart attack, stroke and coronary heart disease).

The data was collected through the Behavioral Risk Factor Surveillance System, a national survey conducted annually by the CDC.

Among all adults aged 18 to 74 years old, any cannabis use — whether smoked, ingested or vaporized — was associated with a higher risk of adverse cardiovascular outcomes, researchers found.

The risk was higher with more frequent cannabis use, but was present even among people who used it less often. For example, daily cannabis users had a 25% greater risk of heart attack, and a 42% higher risk of stroke, compared to non-users.

The results were similar even after researchers controlled for other cardiovascular risk factors such as use of tobacco cigarettes or nicotine e-cigarettes, alcohol consumption, body mass index (BMI), type 2 diabetes and physical activity level.

In a separate analysis, researchers found that cannabis users who had never smoked tobacco or used nicotine e-cigarettes still showed an increased risk of coronary heart disease, heart attack or stroke.

In addition, younger adults at risk for premature cardiovascular disease — men younger than 55 years old and women younger than 65 years old — who used cannabis had a 36% higher risk of coronary heart disease, heart attack or stroke.

Dr. Geoffrey C. Williams, clinical professor of internal medicine at University of Michigan Health, said the results show “there is a strong and consistent effect of cannabis smoking on heart attacks and strokes — even in younger individuals.”

Part of this increased risk may be due to breathing in fine particulate matter, which has been shown to damage blood vessels and the heart.

“We know that low amounts of exposure to smoke, even secondhand cannabis or tobacco smoke, substantially increases risk for stroke and heart attack,” Williams told Healthline.

One study in rats also showed that exposure to just one minute of secondhand cannabis smoke impaired the functioning of blood vessels.

Williams cautions that cannabis smoke contains more than just tetrahydrocannabinol (THC), the active component of cannabis. Those other chemicals may also have negative effects on the heart and blood vessels.

The bottom line: “When people consider taking anything, be aware of the effects of all the contents of the substance,” he said, adding that “smoking is never a safe way to take drugs.”

Smoke inhalation is just one potential way for cannabis to harm the heart and blood vessels, the authors of the new study point out.

For example, some research suggests that cannabis may have negative effects by activating cannabinoid receptors found throughout the cardiovascular system. In addition, THC can affect blood flow, in a way that may increase the risk of stroke and heart attack.

The new study had some limitations, including its observational nature, which means researchers can’t show cause-and-effect, only that there is an association.

Also, researchers relied on participants to report their cardiovascular risk factors and whether they had a heart attack or stroke. They also didn’t have data on participants’ blood pressure or cholesterol levels, two other key cardiovascular risk factors.

However, Dr. Guy L. Mintz, director of Cardiovascular Health & Lipidology at Sandra Atlas Bass Heart Hospital at North Shore University Hospital in Manhasset, New York, pointed out that even without knowing blood pressure and cholesterol levels, researchers still saw a strong link between cannabis use and adverse cardiovascular outcomes.

However, people with uncontrolled blood pressure or high cholesterol may be at higher risk from cannabis. Additional studies would be needed to assess that.

Loren E. Wold, PhD, a professor in the Department of Surgery at The Ohio State University, in Columbus, Ohio, also thinks more research is needed on the heart-related effects of edibles.

Cannabis edibles can include gummies, brownies, cookies and other products, with some edibles having very high THC levels.

While the study included people who used cannabis edibles or vaped cannabis, the researchers didn’t look at the cardiovascular risks for these groups separately.

So, “there needs to be more work done on the type of edible, not just whether it’s an edible or not, but the actual type of edible,” Wold told Healthline.

We need to really look at “what the potential risks are of all the various types of cannabis products,” he said, “and that’s going to take a significant amount of time.”

Some of the shortcomings of the new study could be addressed in future research, such as by enrolling participants and following them from that point forward to see how many develop cardiovascular problems.

With this kind of prospective study, research teams could use medical records to verify whether a person had a heart attack or stroke, and measure blood pressure and other cardiovascular risk factors directly. They could also gather more detailed information about cannabis use, including frequency and types of products.

In spite of the limitations of the new study, Mintz said the findings are a wake-up call for both the general public and physicians about the potential risks of cannabis.

“This is an opportunity for people who engage in cannabis use, recreationally or medically, to talk to their doctor and review their other cardiovascular risks,” Mintz told Healthline, especially those who already know they are at higher risk of heart problems.

Physicians should also routinely ask patients about cannabis use, he said, the way they assess blood pressure, cholesterol, weight and other factors.

“Cannabis use could be considered another potential cardiovascular risk factor,” he said, “one that’s overlooked.”

Wold said the new findings will also allow people to weigh the risks and benefits of cannabis, which is especially important in middle-aged and older adults, who may have other cardiovascular risk factors.

“Cannabis products can be effective for treating sleeplessness or chronic pain,” said Wold. “But is using cannabis worth the risk of compromised cardiac function?”

In a study of over 430,000 U.S. adults, researchers found that cannabis use was associated with increased cardiovascular risks, including heart attack, stroke, and coronary heart disease. The risk was higher with more frequent cannabis use.

This was true even when researchers took into account other risk factors such as tobacco use, alcohol consumption, body mass index (BMI), type 2 diabetes, and physical activity level.

Even in people who had never used tobacco cigarettes or nicotine e-cigarettes, cannabis use was linked to a higher risk of adverse cardiovascular outcomes. Younger people saw a similar risk with cannabis use.