Frequent use of marijuana may increase the risk of heart attack, research suggests

People who frequently smoke marijuana are at a higher risk of heart attack and stroke, according to a study published Wednesday.

The articlepublished in The Journal of the American Heart Association, is an analysis of responses to the U.S. government’s annual behavioral risk survey from 2016 to 2020.

Respondents answered health questions, including reporting their own health problems related to heart disease.

About 4 percent of respondents reported daily marijuana use, which the researchers said increased the risk of heart attack by 25 percent and stroke by 42 percent. Among those who never smoked tobacco, daily use was linked to a 49 percent higher risk of heart attack and a more than doubled risk of stroke, the study found.

About three-quarters of respondents indicate that smoking is the main way they use marijuana. The other quarter consumed it through vaping, edibles or drinking.

“Cannabis smoke releases the same toxins and particulate matter as tobacco,” said the study’s first author, Abra M. Jeffers, a data analyst at Massachusetts General Hospital in Boston. She conducted the analysis during her postdoctoral fellowship at the University of California, San Francisco.

The study is purely observational in terms of assessing survey responses; it does not provide conclusive evidence that regular marijuana use causes heart disease.

Still, researchers and experts said they were concerned about its effects, especially as cannabis use has increased in recent years. Thirty-eight states have legalized medical use of marijuana, and 24 have begun to allow recreational use.

Dr. Nora D. Volkow, director of the National Institute of Drug Abuse, said in an email that as cannabis consumption has increased, “there has also been an increase in the occurrence of adverse health effects, including addiction, respiratory problems, accidents, psychosis and cardiovascular events.”

The U.S. Drug Enforcement Administration is considering whether to follow the recommendations of a team of federal scientists from the Food and Drug Administration, who concluded last year that marijuana should be reclassified into a less restrictive category of controlled substances. They cited a lower potential for abuse than other drugs, as well as marijuana’s possible medical benefits.

But the authors of the new paper warned that frequent marijuana use “could be an important, unappreciated risk factor that could lead to many preventable deaths.”

“This study shows that smoking cannabis can be as harmful as smoking tobacco,” said Dr. Salomeh Keyhani, professor of medicine at the University of California, San Francisco, and lead author of the study.

“Cannabis is marketed to the public as a substance that is harmless and might be good for you,” added Dr. Keyhani added. “I fear we are sleepwalking into a public health crisis. The progress on tobacco smoking could be reversed.”

Heart disease is already the leading cause of death in the country. According to the Centers for Disease Control and Prevention, 695,000 Americans died in 2021 from cardiovascular causes, such as coronary artery disease.

Other studies have documented the surge in marijuana consumption. The percentage of Americans reporting marijuana use rose from 7 percent in 2013 to 17 percent last year, according to a Gallup poll.

A study published in August and funded by the National Institute of Drug Abuse offered more details about consumption by age. From 2012 to 2022, reported use among adults under 30 increased from 28 percent to 44 percent, while daily use increased from 6 percent to 11 percent. Among 35 to 50 year olds, the share of total use rose from 13 percent to 28 percent.

A 2023 federal survey documented past-year marijuana use among 8 percent of eighth graders, 18 percent of 10th graders and 29 percent of twelfth graders.

The new study was funded by the National Heart, Lung and Blood Institute, which is part of the National Institutes of Health. The surveys analyzed came from 434,104 respondents, who were between 18 and 74 years old. Sixty percent were white, 12 percent were black and 19 percent were Hispanic.

Dr. David C. Goff, director of a cardiovascular division at the institute that funded the study, cautioned that comparing the theoretical harms of smoking tobacco versus marijuana was challenging because of the different consumption patterns. People tend to consume more cigarettes per day, but marijuana users tend to inhale marijuana more deeply and hold it longer.

“What we can say is that putting smoke in your lungs is a bad idea,” he said.

Even relatively occasional marijuana use was linked to heart disease in the new study. Weekly use was linked to a 3 percent greater risk of heart attack and a 5 percent greater risk of stroke.

Robert Page, a pharmacist at the University of Colorado School of Medicine in Aurora who was not involved in the new study, said patients and their health care providers should have open conversations about cannabis use. But he added that even doctors were often unaware of the risks.

“People don’t know the data,” he said. “They think it’s safe because it’s natural.”