As marijuana becomes legal and widely used in many parts of the world, including large parts of the United States, new research is raising concerns about its effects on heart health. Two recent studies suggest that using cannabis may significantly increase the risk of having a heart attack—even among younger, otherwise healthy adults.
These findings come from a large-scale retrospective study published in JACC Advances and a separate meta-analysis of 12 previously published studies, which was presented at the American College of Cardiology’s Annual Scientific Session (ACC.25) in March 2025.
A Closer Look at the New Findings
The retrospective study analyzed health data from more than 4.6 million people under age 50 using a global electronic medical records network called TriNetX. None of the individuals in the study had high blood pressure, high LDL (bad) cholesterol, diabetes, or a history of smoking or heart disease. In short, they were considered low-risk for heart problems.
Despite this, researchers found that cannabis users were:
- 6 times more likely to have a heart attack
- 4 times more likely to experience an ischemic stroke
- 2 times more likely to develop heart failure
- 3 times more likely to suffer cardiovascular death or a major cardiac event
“These are patients we wouldn’t normally think of as being at high risk for heart disease,” said Dr. Ibrahim Kamel, the lead author of the study and a clinical instructor at Boston University. “This should change how we screen and talk to patients about marijuana use.”
Meta-Analysis Confirms the Trend
In the second study, researchers conducted a meta-analysis, meaning they combined and re-analyzed data from 12 different studies involving over 75 million people. Although individual studies showed mixed results, the combined data showed that cannabis users were 50% more likely to suffer a heart attack than non-users.
The average age across these studies was about 41 years, suggesting the risk extends to relatively young people. Seven of the 12 studies found a significant link between marijuana and heart attacks. Four showed no link, and one showed a slight decrease in risk. However, when the data were pooled, the connection between marijuana use and increased heart attack risk was statistically clear.
What Might Be Causing This?
While the exact biological reasons behind these effects are still being studied, experts have a few ideas:
- Disrupted heart rhythms: Marijuana may interfere with the heart’s electrical signals.
- Higher oxygen demand: The heart may need more oxygen than usual after cannabis use, which can stress the heart muscle.
- Blood vessel dysfunction: Marijuana may impair the ability of blood vessels to relax, making it harder for blood to flow properly.
- Immediate effects: One study found that the risk of heart attack is highest in the first hour after using marijuana.
Limitations and Considerations
Both the retrospective study and the meta-analysis have their limitations. Because the research was observational and not experimental, it can’t prove cause and effect. Also, not all the studies included detailed information about how much marijuana people used, for how long, or whether they also used other drugs like tobacco or cocaine.
Still, the large number of participants and the consistency of the findings across different studies make the results hard to ignore.
Dr. Kamel emphasized that patients should be open with their doctors about cannabis use. “We’re not here to judge—we’re here to help. But we can’t help if we don’t have the full picture,” he said.
A Wake-Up Call for Patients and Providers
For decades, tobacco has been a focus in discussions around heart health. Now, with marijuana use on the rise, it may be time to start treating cannabis use with similar caution—especially in younger adults who assume they are not at risk.
“Clinicians should ask about cannabis use the same way we ask about smoking or alcohol,” said Dr. Kamel. “At the very least, people deserve to be informed that this behavior might be putting their heart health at risk.”
A previous study from 2023 already linked daily marijuana use to an increased risk of coronary artery disease, and the latest findings only strengthen concerns about cannabis and heart health.
Final Thoughts
Legal doesn’t always mean safe. As public perception of marijuana shifts toward normalization, these studies serve as an important reminder: cannabis use may carry serious health risks—especially for the heart.
More research is still needed, but if you or someone you know uses marijuana regularly, it’s worth having an honest conversation with your doctor about the potential risks and how to stay heart-healthy.
In the meantime, don’t assume that being young or feeling healthy is enough protection. As these studies show, even people in their 30s or 40s with no previous heart issues could still be at risk.
If you care about health, please read studies about the benefits of low-dose lithium supplements, and what we know about egg intake and heart disease.
For more health information, please see recent studies about potatoes and high blood pressure, and results showing 6 best breads for people with heart disease.
The research findings can be found in JACC: Advances.
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