Recreational marijuana, or cannabis, is legal in 24 states and Washington, D.C. The 2019 National Survey on Drug Use and Health also reported the number of people in the U.S. who use cannabis has increased significantly in recent decades. The yearly survey found that in 2019 about 48 million people ages 12 and older reported they had used cannabis at least once, versus almost 26 million people in 2002.

Despite increasing use, little is known about the effects cannabis has on health, particularly the associated cardiovascular risks.

Researchers from the University of California at San Francisco and Massachusetts General Hospital found that ingesting cannabis was associated with poor cardiovascular outcomes such as heart disease, heart attack and stroke. These risks rose with the frequency of cannabis use.

Using cannabis in any form — whether smoked, vaped or eaten — increased the odds of a person developing cardiovascular problems like heart disease, heart attack and stroke.

People might not associate cannabis with negative health outcomes, even though they know about tobacco's negative outcomes, Abra Jeffers, lead author on the study, told TheDoctor. “The public should be aware of the risks associated with cannabis, so they can temper their use as they see fit,” she said.

Data from more than 430,000 respondents to the Behavioral Risk Factor Surveillance Survey between 2016 and 2020 were analyzed for the study. Respondents lived in 27 states and two U.S. territories and were between the ages of 18 and 74. The association between marijuana use and cardiovascular outcomes was analyzed in the general population; among those who never used e-cigarettes or smoked tobacco; and among younger adults, defined as women under the age of 65 and men under the age of 55, at risk for early heart disease.

Four percent of respondents used cannabis daily and seven percent did so less frequently. Smoking marijuana was the most common method of ingesting cannabis, but cannabis use in any form — whether smoked, vaped or eaten — increased the odds of a person developing cardiovascular problems like heart disease, heart attack and stroke.

Daily users had a 25 percent higher risk of heart attack than those who did not use cannabis. Less frequent users still had an increased risk of heart attack versus non-users. Daily users also had a 42 percent higher risk of stroke than non-users, while the stroke risk for less frequent users, compared to non-users, was lower but still higher than for non-users.

“The effect of cannabis use on heart attack and stroke is still there even if we limit the sample to those who had never used tobacco.”

Cannabis use increased the combined risk of heart disease, heart attack and stroke by 36 percent among younger adults at risk for early heart disease, regardless of whether or not they also used tobacco products. Data from a subgroup of these young adults who never used tobacco products or e-cigarettes were analyzed separately. This analysis also found a significant association between cannabis use and the combined risk of heart disease, heart attack and stroke.

This was perhaps the most surprising finding, indicated Jeffers, a data analyst at Massachusetts General Hospital. “The effect of cannabis use on heart attack and stroke is still there even if we limit the sample to those who had never used tobacco,”

People may be surprised that cannabis has a similar association with cardiovascular disease risk as tobacco, but they shouldn't be, said Jeffers. Endocannabinoid receptors are found throughout the cardiovascular system, making it highly responsive to the cannabinoids released during cannabis use, she explained, adding that smoking cannabis also releases a lot of the same toxins and particulate matter that smoking tobacco does.

The authors note the following limitations to the study: Cannabis use was self-reported, making it a less reliable measurement; participants' blood pressure and lipid profile at baseline were not available; and the study only captured data from one point in time. In the future, prospective studies that follow people over time, while accounting for the frequency of cannabis use, are needed to further examine the association between cannabis use and cardiovascular outcomes.

The study is published in the Journal of the American Heart Association.