Marijuana addiction may raise the risk of a first heart attack or stroke by 60%

That’s according to a new study from University of Calgary’s Cumming School of Medicine in Canada, published in the journal Addiction.

Researchers examined the records of nearly 60,000 Canadian patients who hadn’t experienced an adverse cardiovascular event as of January 2012, and followed them through December 2019. Half of study participants had cannabis use disorder—defined by the inability to stop using marijuana even though it causes health and social issues—and half did not.

Nearly 2.5% of people with the disorder experienced their first major cardiovascular event during those eight years, compared with just 1.5% among those without the disorder, researchers found.

The study doesn’t provide enough information to link cannabis use with adverse cardiac events, lead researcher Dr. Anees Bahji—a clinical assistant professor of psychiatry at the university—said in a news release. 

“But we can go so far as to say that Canadians with cannabis use disorder appear to have a much higher risk of cardiovascular disease than people without the disorder,” he said.

Daily marijuana use is linked with coronary artery disease

The study’s findings come as no surprise. Those who use marijuana daily are about a third more likely to develop coronary artery disease than those who’ve never used the recreational drug, according to a study published in February.

“There are probably certain harms of cannabis use that weren’t recognized before, and people should take that into account,” Dr. Ishan Paranjpe, a physician at Stanford University and the study’s lead author, said in a news release at the time.

Those who used cannabis monthly did not show an increased risk of coronary artery disease, researchers found.

Given the risks that come with marijuana use, users should let their doctors know about their habit for the purpose of monitoring heart health, researchers said in the release. 

Marijuana smoke contains “many of the same toxins, irritants, and carcinogens found in cigarette smoke, a known contributor to heart disease, as well as cancer.” Its effects on the cardiovascular system have yet to be well studied because it’s illegal at the federal level, resulting in restrictions on researchers, according to Harvard Health Publishing.

Cannabis is legal in Canada at the federal level.

“As a result, everything we’re told about what marijuana does or doesn’t do should be viewed with a certain amount of caution,” the organization writes. “This holds equally true for the risks as well as the benefits.”

That said, cannabis consumption has been shown to cause arrhythmia and fast heartbeat, and potentially sudden death, as well as to increase one’s risk of heart attack, according to a 2017 article in the Journal of Thoracic Disease. Other studies suggest there are links between marijuana and atrial fibrillation, the most common heart rhythm disorder, and that smoking pot may raise the risk of stroke, according to Harvard Health.

Nearly half of U.S. states have legalized recreational use of marijuana, and the majority allow its use for medicinal purposes. Nearly 90% of U.S. adults think marijuana should be legal, either for recreational and medical use, or just for medical use, according to a November 2022 report from the Pew Research Center. 

More than 2 million Americans with known cardiovascular disease are thought to have used marijuana, according to a 2020 article published in the Journal of the American College of Cardiology.