While most Americans consider marijuana safe, new research published this week found that use of the drug is associated with a higher risk of stroke and heart attack, including among younger adults.
The analysis, which examined data from 24 studies and was published in the journal Heart, also found that marijuana use was associated with a twofold increase in the risk of death from cardiovascular disease. While this data only shows a correlation and cannot prove that marijuana caused these effects, it is well-established that the drug can raise blood pressure and heart rate and alter the heart’s rhythm, said Dr. Ersilia DeFilippis, a cardiologist at Columbia University Irving Medical Center. And a number of other studies have also suggested a link between the drug and cardiovascular issues.
The analysis comes at a time when nearly half of U.S. states have legalized marijuana for recreational use, and when a record share of U.S. adults — 15 percent in 2022 — report using it. Emilie Jouanjus, the senior author of the new study and a pharmacologist at the University of Toulouse in France, said that while there may be good reasons for people to take marijuana, including for stress and anxiety, patients can’t assume that it is harmless.
She and other experts said that everyone should be treating marijuana with caution, and suggested several ways people can mitigate their risk.
Who is most at risk?
Generally speaking, older adults and people with underlying conditions such as diabetes, high cholesterol or pre-existing heart issues are at the greatest risk, experts said. That’s because their cardiovascular systems tend to be more fragile, and marijuana further stresses the heart. In 2023, about 7 percent of U.S. adults age 65 and older reported using marijuana in the past month.
But the average age of patients included in the new analysis was just 38, an indication that marijuana increases risks among younger people, too.
Dr. John Ryan, a cardiologist at University of Utah Hospital, said these findings concerned him. He has himself seen heart attacks in otherwise healthy people who use marijuana regularly and noted that many young people don’t know the signs of heart attacks or strokes, which can include chest pain and sudden weakness or numbness.
Research suggests that while cardiovascular issues aren’t common in people who use marijuana, they happen frequently enough to warrant concern. These risks are most likely similar to those of light smoking, said Stanton Glantz, the former director of the Center for Tobacco Control Research and Education at the University of California, San Francisco.
How much marijuana is too much?
The new analysis didn’t examine how frequently people used marijuana; it only compared people who had ever used marijuana with those who had never used it.
Still, experts said it’s likely that the more often people use marijuana, the higher their risk of cardiovascular issues. One 2024 study suggested that weekly use was associated with 3 percent higher odds of a heart attack and 5 percent higher odds of a stroke, compared to people who didn’t use marijuana. But daily use was associated with 25 percent higher likelihood of a heart attack and 42 percent higher likelihood of stroke. There isn’t good data on the risk with less frequent use.
While these risks seem most likely to occur with long-term exposure, there can also be short-term harms, said Ziva Cooper, the director of the Center for Cannabis and Cannabinoids at the University of California, Los Angeles. One 2001 study suggested that heart attack risk is highest in the hour after smoking marijuana.
The amount of marijuana people are using — and how much tetrahydrocannabinol, or T.H.C., is in it — most likely matters too. But it’s difficult to research this, since most people don’t know how much T.H.C. they’re taking in, and even labeled products may list inaccurate amounts, Dr. Cooper said.
Are there ways to lower the risk?
Dr. Salomeh Keyhani, a primary care physician at the San Francisco Veterans Affairs Medical Center, tells her patients who are going to use marijuana to do so infrequently, and to opt for products with as low a T.H.C. concentration as possible.
She and other experts also suggested that people avoid inhaling marijuana. While researchers don’t yet know how the cardiovascular risks vary between smoking and edibles, smoking likely poses a greater threat because it involves inhaling thousands of chemicals deep into the lungs, said Matthew Springer, a biologist studying heart disease at the University of California, San Francisco. In May, his lab reported that regularly taking edibles or smoking marijuana was linked to similar amounts of blood vessel dysfunction.
Dr. Cooper said that anyone who uses marijuana should talk to their doctor about the potential for heart problems, and recommended that seniors and anyone at high risk of cardiovascular disease avoid the drug altogether. She added that it may be safer to get marijuana from a licensed dispensary rather than on the black market, because the potency and purity of the drug is better regulated.
While there’s still much that researchers don’t know about marijuana and cardiovascular issues, experts said there’s enough evidence to be cautious.
The post Marijuana’s Links to Heart Attack and Stroke Are Becoming Clearer appeared first on New York Times.
