Think Smoking Cannabis Won’t Damage Your Heart? Think Again.

The cardiac risks of smoking marijuana are comparable to those of smoking tobacco, according to researchers at UC San Francisco, who warn that the increasing use of cannabis across the country could lead to growing heart health problems.  

The study found that people who used cannabis daily had a 25% increased risk of heart attack and a 42% increased risk of stroke compared to non-users.  

Cannabis has become more popular with legalization. Recreational use is now permitted in 24 states, and as of 2019, nearly 4% said they used it daily and 18% used it annually. That is a significant increase since 2002, when 1.3% said they used it daily and 10.4% used it annually.  

“Cannabis use is increasing in both prevalence and frequency, while conventional tobacco smoking is declining,” said Salomeh Keyhani, MD, MPH, professor of medicine at UCSF and senior author of the study, which appears Feb. 28, 2024, in the Journal of the American Heart Association. “Cannabis use by itself might, over time, become the more important risk factor.”

Cardiac risks for those who never used tobacco 

The researchers used data from the Behavioral Risk Factor Surveillance System, a national cross-sectional survey conducted by the Centers for Disease Control and Prevention to examine the association between cannabis use and adverse cardiovascular outcomes including coronary heart disease, heart attack and stroke.   

They examined whether cannabis use was associated with coronary heart disease, acute myocardial infarction and stroke among the general adult population and among people who had never smoked tobacco.  

Among the 434,104 respondents, about 4% were daily users, 7.1% were non-daily (about five days in the month) and 88.9% had not used any marijuana in the past 30 days. Among current users, about three-fourths said they mostly smoked it.  

The study found that cannabis use was independently associated with adverse cardiovascular outcomes, and the odds rose with the number of days per month that a person used it.  

The study also examined the effects for those who had never smoked or vaped tobacco, finding that just smoking cannabis was associated both with stroke, and with the combination of coronary heart disease, heart attack and stroke.   

“This is an important public health finding, particularly given our ongoing efforts to reduce the burden of heart disease in this country,” said David C. Goff, M.D., Ph.D., director of the Division of Cardiovascular Sciences at the National Heart, Lung, and Blood Institute (NHLBI), which is part of the National Institutes of Health. 

The perception of risk needs to change 

People who smoke cannabis often hesitate to disclose it to their physicians, in part because they don’t consider it as harmful as smoking tobacco, and many states, like California, first approved it for medical uses. The researchers noted it will be an uphill battle to change these attitudes. 

“There is a multibillion-dollar cannabis industry that markets cannabis use as not only harmless, but good for you,” Keyhani said. “It can be a challenging discussion to have with patients because there is evidence that cannabis has some therapeutic properties. However, as suggested by this study, cannabis use also has significant cardiovascular risks.”   

Co-authors: Additional UCSF co-authors include Stanton Glantz, PhD, and Amy L. Byers, PhD, MPH.   

Funding: NHLBI 1R01HL130484-01A1 and National Cancer Institute (grant T32 CA113710). 

Disclaimer: The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.