How does marijuana affect the heart?

More Americans now use marijuana than smoke cigarettes. But the drug may be risky for those with heart disease.

Growing numbers of Americans use marijuana, including baby boomers in their 60s, 70s, and beyond. To date, 11 states and the District of Columbia have legalized marijuana for recreational purposes. And 33 states allow doctors to prescribe marijuana to treat certain health problems, including pain, anxiety, and depression.

Compared with other prescription drugs, the health consequences of using marijuana are not nearly as well studied (see "Stuck in the weeds: The problem with pot research"). But converging evidence suggests that the drug may be harmful for the heart, according to a January 28 review article in JACC: Journal of the American College of Cardiology. More than two million Americans with heart disease currently use or have used marijuana, the authors estimate.