As cannabis legalization spreads and perceptions shift, a growing body of evidence points to a health risk that’s flown under the radar: the heart.
A new systematic review and meta-analysis of real-world data found that people who use cannabis face higher risks of major adverse cardiovascular events — including stroke, heart attack, and cardiovascular death. With recreational use now legal in parts of Europe and widely accepted in North America, the findings come at a critical moment.
Analyzing Millions to Understand the Risk
Researchers reviewed 24 studies involving over 432 million patients across various populations. They found that cannabis use was associated with:
- A 29% higher risk of acute coronary syndrome (RR = 1.29)
- A 20% increased risk of stroke (RR = 1.20)
- More than double the risk of cardiovascular death (RR = 2.10)
The research focused on major adverse cardiovascular events (MACE) — a clinical category including non-fatal heart attacks, strokes, and deaths from heart-related causes.
Why Are These Effects Happening?
The study explored several possible biological explanations. Cannabinoids like THC and CBD act on CB1 and CB2 receptors, which affect the cardiovascular system in complex ways. Activation of the CB1 receptor has been linked to oxidative stress, inflammation, and vascular dysfunction. As the authors note, “CB1 activation in the cardiovascular system has been associated with oxidative stress, tissue injury, cell death, proatherogenic, profibrotic, proinflammatory effects.”
Meanwhile, high-potency cannabis products with elevated THC levels are more common today than a decade ago. These may intensify effects like vasoconstriction — the narrowing of blood vessels — which, in turn, increases the heart’s oxygen demand and may trigger ischemia.
Uneven Effects: Age and Gender Matter
The study didn’t just pool data. It looked closely at variations across age groups and gender. Some findings stood out. Among young adults aged 18–36, cannabis use was linked to a significantly higher risk of acute coronary syndrome. In one analysis, the odds ratio in that age group was 5.24.
In addition, an underreported result from a 2024 UK Biobank analysis revealed that heavy cannabis use was tied to elevated cardiovascular mortality in women, but not in men. This sex-based difference adds complexity to the overall picture and underscores the need for more targeted research.
Real-World Implications
While the review included data from medical and recreational cannabis users, only one study focused exclusively on medical cannabis. Still, the takeaway was clear. “The findings outlined by this meta-analysis should enhance the general awareness of the potential of cannabis to cause cardiovascular harm,” the authors wrote.
They recommend that physicians routinely ask about cannabis use when evaluating patients with serious cardiovascular symptoms — especially since many users do not disclose use, and some may be self-medicating without a prescription.
Key Takeaways for Policy and Practice
The study authors emphasized that better real-world data is needed, especially with accurate cannabis exposure measures. But based on current evidence, they recommend:
- Including cannabis use in cardiovascular patient evaluations
- Increasing public awareness about cannabis-related heart risks
- Conducting further sex-specific and age-specific research
What’s Next?
As global cannabis use continues to rise, so does the need for nuanced understanding. Could the health risks vary by dose, method of use, or cannabinoid profile? How do new high-THC strains alter risk patterns? Until we know more, this study urges caution.
In a time of changing laws and evolving perceptions, one thing remains steady: the heart doesn’t lie.
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