New research shows that people who use marijuana may have a much higher risk of heart attack—even if they are young and healthy.
Two major studies have added to growing concerns about how cannabis affects the heart.
One study, published in JACC Advances, analyzed the medical records of over 4.6 million people.
It found that marijuana users under 50 were more than six times more likely to have a heart attack compared to those who didn’t use the drug.
Another study, presented at the American College of Cardiology’s Annual Scientific Session (ACC.25), combined data from 12 past studies and found that cannabis users had a 50% higher chance of heart attack than non-users.
Marijuana use has become more common in the U.S., especially in places where it is legal. But doctors warn that its effects on the heart should not be ignored.
Dr. Ibrahim Kamel, the lead author of the study, says doctors should ask about marijuana use just as they ask about smoking cigarettes, as it could be an important risk factor for heart disease.
The first study used a health research database called TriNetX to track people’s health records for over three years. It found that marijuana users had:
- 6x higher risk of heart attack
- 4x higher risk of stroke
- 2x higher risk of heart failure
- 3x higher risk of heart-related death
What makes these results striking is that all participants were young (under 50) and had no previous heart problems. They also had normal cholesterol and blood pressure, didn’t have diabetes, and didn’t smoke tobacco.
The second study—a meta-analysis—combined data from 12 previous studies with over 75 million people. It found that seven out of 12 studies showed a strong link between marijuana use and heart attacks. Even though some studies showed no clear connection, when all the data was combined, the risk of heart attack was significantly higher for cannabis users.
How does marijuana affect the heart?
Experts don’t fully understand how cannabis harms the heart, but there are a few possible explanations. Marijuana may:
- Affect heart rhythm
- Increase oxygen demand in the heart
- Make it harder for blood vessels to relax
Some research even suggests that the risk of a heart attack is highest within an hour of using marijuana.
Important warnings
These studies had some limitations. For example, they didn’t always account for how much marijuana people used or whether they used other drugs like cocaine.
Dr. Kamel warns that many cannabis users also use other substances, which could influence the results.
Still, the findings raise serious concerns. As marijuana becomes more widely accepted, people should be aware of the potential risks—especially young users who believe it’s completely safe.
More research is needed, but for now, being honest with your doctor about marijuana use is crucial for protecting your heart health.
