Cannabis Tied to Sharply Higher Heart-Attack Risk, Even in Healthy Under-50s

Two new analyses presented around the American College of Cardiology’s 2025 meeting strengthen the case that cannabis use raises cardiovascular risk. A retrospective study of more than 4.6 million people, published in JACC Advances, found that users under 50 were more than six times as likely to have a heart attack than non-users. The same cohort — all under 50 and free of major cardiac risk factors like diabetes, tobacco use, high LDL, or prior coronary disease — also showed roughly four times the risk of ischemic stroke, double the risk of heart failure, and triple the combined risk of cardiovascular death, heart attack, or stroke over about three years of follow-up.

The second analysis pooled 12 prior studies covering over 75 million people (average age 41), making it the largest combined look at cannabis and heart attacks to date. Individually the studies were mixed — seven found a significant positive association, four found none, and one leaned slightly negative — but pooled together they pointed to a 50% higher heart-attack risk among active users. Researchers propose plausible mechanisms including disrupted heart rhythm, increased myocardial oxygen demand, and endothelial dysfunction; one included study found risk peaking about an hour after use.

The authors are careful about limitations. Both efforts are retrospective, and the pooled data couldn’t control for dose, duration, tobacco, or co-use of other drugs such as cocaine — meaningful confounders. Their practical takeaway is that clinicians should ask about cannabis as routinely as they ask about cigarettes, and that consumers deserve clear warnings about cardiovascular risk. Prospective studies, they say, are needed to confirm the link and identify who is most vulnerable.