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% of US adults aged 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 the University of Utah Hospital, said these findings concerned him.
He has 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 Centre 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% higher odds of a heart attack and 5% higher odds of a stroke, compared with people who didn’t use marijuana.
But daily use was associated with 25% higher likelihood of a heart attack and 42% 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 Centre for Cannabis and Cannabinoids at UCLA.
One 2001 study suggested that heart attack risk is highest in the hour after smoking marijuana.
The amount of marijuana people use – and how much tetrahydrocannabinol, or THC, is in it – most likely matters too.
But it’s difficult to research this, since most people don’t know how much THC they’re taking in, and even labelled products may list inaccurate amounts, Cooper said.
Are there ways to lower the risk?
Dr Salomeh Keyhani, a professor of medicine at UCSF, tells her patients who are going to use marijuana to do so infrequently, and to opt for products with as low a THC 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.
Cooper said that anyone who uses marijuana should talk to their doctor about the potential for heart problems and recommended that elderly people 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.
This article originally appeared in the New York Times.
Written by: Simar Bajaj
Photographs by: Joanna Kulesza
©2025 THE NEW YORK TIMES
