At a Glance

Q: Can marijuana harm your heart?
A: Yes. THC can strain your arteries and raise your risk for heart attack—more than cocaine. Find out how.

• THC accelerates heart rate and blood pressure.
• Risk starts with your first use.
• Safer alternatives exist for stress relief.

Recreational cannabis sales began in August 2024, making the drug more available to the public over the past year.

With cannabis now being sold in stores, some may assume that it’s a safe substance. But Dr. Harvey Hahn, a cardiologist, warns that this isn’t the case. 

Studies show that THC, or tetrahydrocannabinol, one of the main compounds in cannabis, has harmful effects on our health—especially our hearts. 

What does THC do to the heart?

Despite its perceived calming effect, ingesting THC quickens our heart rate and increases our blood pressure. 

“So,” Dr. Hahn says, “the shear stress in your blood vessels is higher.”

Increased shear stress, or friction on the artery walls, increases the risk for acute heart attacks (a lack of blood flow to the heart) and stroke (a lack of blood flow to the brain). Both of these conditions can be life-threatening. 

And the risk of smoking cannabis or taking edibles is more significant than you might think. 

Heart attack and stroke risk increases by 20 to 30 percent when using THC—making it more harmful for the heart than cocaine. 

“People think you’re relaxed, so you should be healthier when you’re taking marijuana versus cocaine when you’re amped up and stressed out,” Dr. Hahn says. “But marijuana is actually more closely associated with causing heart attacks than cocaine.” 

Dr Hahn warns against using THC products, even if you’re young and have no preexisting heart conditions.  

Natural isn’t always safe 

Because THC comes from a plant, people might think it’s safer than medications your doctor prescribes. But, according to Dr. Hahn, this isn’t true. 

“There are so many things in nature that are harmful to you,” Dr. Hahn says. This includes plants that appear safe, like some wild mushrooms or berries, but are toxic when consumed. 

There is growing distrust around pharmacies and Western medicine, but when prescribing medication, your doctor will consider your medical history and existing prescriptions, limiting the risk of negative side effects.

Dr. Hahn also emphasizes a zero threshold for using THC. While chronic use increases your risk over time, the risk begins when you start using it. 

“Every time you do it,” Dr. Hahn says, “you’re exposing yourself to some level of risk.”