Recent headlines claim cannabis use doubles the risk of dying early from heart disease, based on a large analysis of 24 international studies. While that sounds alarming, the science behind the claim is more complicated than the headlines suggest.
Cannabis use in Cape Town has become ubiquitous, with clubs selling a variety of products popping up everywhere.
Below is a break-down of why the quoted study’s findings are flawed.
The key issue: this shows correlation, not causation
The analysis found that people who used cannabis had higher rates of heart attacks, strokes, and cardiovascular death than non-users. But most of the studies included were observational, meaning researchers watched what people were already doing rather than controlling who used cannabis.
That makes it impossible to prove that cannabis caused the heart problems. Other factors could help explain the link, including:
- Tobacco use
- Diet and exercise habits
- Alcohol or other drug use
- Underlying health conditions
Many of the studies also relied on self-reported cannabis use, which isn’t always accurate.
Correlation essentially means this: Every summer, both ice cream sales and drowning deaths go up. Does eating ice cream cause drowning? Of course not.
The numbers sound dramatic – but lack detail
The analysis reported:
- A 29% higher risk of heart attack or angina
- A 20% higher risk of stroke
- Double the risk of early cardiovascular death
But the studies grouped together very different people and patterns of use. Most didn’t track:
- How much cannabis people used
- How often they used it
- Whether they smoked, vaped, or used edibles
- Whether cannabis was mixed with tobacco
Without that information, it’s hard to know how much of the risk is actually due to cannabis itself.
Other studies don’t always show the same thing
Some research in specific groups, such as older adults with existing heart disease, has not found a clear link between cannabis use and major heart events. That doesn’t mean cannabis is harmless. It means the risks may vary depending on:
- Age
- Overall health
- Frequency and method of use
Importantly, while this study shows “no clear link found”, it does not mean that it is “definitely safe.”
Scientists like to say: Not finding proof of harm is not the same as proving there is no harm.
What we do know
Cannabis can affect heart rate and blood pressure, which means it could strain the cardiovascular system, especially in people with existing heart problems. But current evidence does not definitively prove that cannabis directly causes heart disease or early death.
Bottom line
The 24-study analysis suggests a possible link between cannabis use and heart risk, but it does not prove cannabis doubles your risk of cardiovascular disease. The relationship is likely more complex and influenced by many other health and lifestyle factors.
Anyone with heart disease or multiple risk factors should discuss cannabis use with a healthcare professional, just as they would with alcohol or tobacco.
