American Heart Association, published in the journal Circulation, sounds the alarm about the potential dangers of its use on the heart and blood vessels.

The statement outlines what we know about the possible benefits and risks of the drug based on existing research. Studies have shown that marijuana—also called pot, weed or cannabis—can help with pain relief, nausea, or vomiting. It also eases muscle stiffness in people with multiple sclerosis and seizures for people with epilepsy. However, there are “no well-documented cardiovascular benefits,” the authors write.

Marijuana stimulates the body’s “fight or flight” reaction that can, for example, lead to a more rapid heart rate (the sympathetic nervous system) while also reducing the body’s ability to  slow heart rate and maintain calm (the parasympathetic nervous system). Some of the reported concerns include the fact that marijuana may:

  • Trigger dangerous heart rhythms, including tachycardia or atrial fibrillation within an hour after smoking products containing the chemical tetrahydrocannabinol (THC) that creates the so-called high people feel; THC can speed heart rate, increase the heart’s need for oxygen, and disrupt the health of the lining of blood vessels.
  • Be linked to heart muscle damage, chest pain, heart attack and other ill effects due to carbon monoxide intoxication similar to what is seen with tobacco smoking.
  • Make strok or heart attack more likely.
  • Interfere with medications that are vital to slowing or preventing cardiovascular disease or events.

The important message is that anyone who is considering using marijuana—and especially those with known heart or blood vessel disease—should talk with a member of their care team. Inhaled or vaping marijuana is especially harmful. The statement emphasized that legal cannabis products taken by mouth or applied to the skin (topical) are a safer option. Also, products sold on the street should be avoided and may be laced with other toxic substances. Cannabidiol, also called CBD, is one of the chemicals found in cannabis does not seem to harm the heart.