People who frequently smoke marijuana have a higher risk of heart attack and stroke, according to a study published on Wednesday.
The article, published in The Journal of the American Heart Association, is an analysis of responses to the U.S. government’s annual survey on behavioral risk from 2016 to 2020.
The respondents answered health questions, including reporting their own health problems related to heart disease.
About 4 percent of the respondents reported daily marijuana use, which the researchers suggested raised the chance of a heart attack by 25 percent and of a stroke by 42 percent. Among those who never smoked tobacco, daily use was tied to a 49 percent higher risk of heart attack and a more than doubled risk of stroke, the study indicated.
About three-quarters of the respondents said that smoking was their main method of using weed. The other quarter consumed it by vaping, through edibles or drinking it.
“Cannabis smoke releases the same toxins and particulate matter that tobacco does,” said the study’s first author, Abra M. Jeffers, a data analyst at Massachusetts General Hospital in Boston. She conducted the analysis during her post-doctoral fellowship at the University of California, San Francisco.
The study is merely observational in its review of survey responses; it does not provide conclusive evidence that regular marijuana use causes heart disease.
Even so, researchers and experts said they were concerned about its implications, especially as cannabis use has increased in recent years. Thirty-eight states have legalized medical use of marijuana, and 24 have begun allowing recreational use.
Dr. Nora D. Volkow, director of the National Institute of Drug Abuse, said in an email that as cannabis consumption has risen, “there has also been an increase in the emergence of adverse health effects including addiction, respiratory problems, accidents, psychosis and cardiovascular events.”
The U.S. Drug Enforcement Administration is weighing whether to follow the recommendations of a team of federal scientists at the Food and Drug Administration, which concluded last year that marijuana should be reclassified to a less restrictive category of controlled substances. They cited a lesser potential for abuse than other drugs have as well as marijuana’s possible medical benefits.
But the new paper’s authors warned that frequent marijuana use “could be an important, unappreciated risk factor leading to many preventable deaths.”
“This study demonstrates that smoking cannabis may be as harmful as smoking tobacco,” said Dr. Salomeh Keyhani, a professor of medicine at the University of California, San Francisco, and the study’s senior author.
“Cannabis is being marketed to the public as a substance that is harmless and might be good for you,” Dr. Keyhani added. “I worry that we’re sleepwalking into a public health crisis. The progress on tobacco smoking might be undone.”
Heart disease is already the nation’s leading cause of death. According to the Centers for Disease Control and Prevention, 695,000 Americans died in 2021 of cardiovascular-related causes, such as coronary artery disease.
Other surveys have documented the surge in consumption of marijuana. The percentage of Americans reporting marijuana use increased to 17 percent last year from 7 percent in 2013, according to a Gallup poll.
A study published in August and financed by the National Institute of Drug Abuse offered more details on consumption by age. From 2012 to 2022, reported use among adults up to age 30 increased to 44 percent from 28 percent, while daily use rose to 11 percent from 6 percent. Among those 35 to 50 years old, the proportion for overall use rose to 28 percent from 13 percent.
A 2023 federal survey documented marijuana use in the past year among 8 percent of eighth graders, 18 percent of 10th graders and 29 percent of 12 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 that were analyzed came from 434,104 respondents, who were 18 to 74 years old. Sixty 60 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 financed the research, cautioned that comparing the theoretical harms of smoking tobacco versus marijuana was challenging because of differing consumption patterns. People tend to consume more cigarettes a day, but marijuana users tend to inhale marijuana more deeply and hold it for longer.
“What we can say is it’s a bad idea to put smoke in your lungs,” he said.
Even relatively casual weed use had an association with heart disease in the new study. Weekly use was tied to a 3 percent greater risk of heart attack and a 5 percent greater chance of stroke.
Robert Page, a pharmacist at the University of Colorado School of Medicine in Aurora who was not involved with the new study, said that 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 because it’s natural, it’s safe.”
