Health

Smoking Weed Is Not Good For Your Heart, Studies Say

August 6, 2020 / 9:30 PM EDT / CBS Baltimore

click to expand

BALTIMORE (CNN) -- You may love smoking weed, but it does not love your heart, according to the American Heart Association's new scientific statement on marijuana.

"The American Heart Association recommends that people not smoke or vape any substance, including cannabis products, because of the potential harm to the heart, lungs and blood vessels," said Dr. Rose Marie Robertson, the deputy chief science and medical officer for the American Heart Association, in a statement.

The new scientific statement, published Wednesday in the AHA journal Circulation, examined existing research on the connection between cannabis and the heart.

The statement found using weed has "the potential to interfere with prescribed medications" as well as "trigger cardiovascular conditions or events, such as heart attacks and strokes," said clinical pharmacologist Robert Page II, who chaired the medical writing group for the statement.

Anyone planning to use marijuana should discuss possible risks with their health professional first, said Page, who is a professor in the department of clinical pharmacy and physical medicine/rehabilitation at the University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences in Aurora, Colorado.

"If people choose to use cannabis for its medicinal or recreational effects, the oral and topical forms, for which doses can be measured, may reduce some of the potential harms," Page said in a statement.

"It is also vitally important that people only use legal cannabis products because there are no controls on the quality or the contents of cannabis products sold on the street," he added.

Heart complications

Some of the studies analyzed by the medical group found heart rhythm abnormalities, such as tachycardia and atrial fibrillation, could occur within the hour after weed containing THC is smoked. THC, or tetrahydrocannabinol, is the psychoactive substance within marijuana that creates a "high."

Tetrahydrocannabinol can also cause a faster heart rate, increase the heart's need for oxygen, disrupt the walls of arteries and contribute to higher blood pressure while prone, according to other studies.

"Cannabis smoke contains components similar to tobacco smoke," Page said, and studies show tobacco-like increases in carbon monoxide and tar in a weed smoker's blood after smoking marijuana, regardless of the THC content.

Chest pain, heart attacks, heart rhythm disturbances and other serious heart conditions are associated with both tobacco and marijuana carbon monoxide intoxication, the statement said.

For anyone with existing heart disease, risks go up. Smoking weed has triggered heart attacks, a higher risk of strokes and heart failure in people with underlying heart disease, studies show.

In comparison, CBD, or cannabidiol, one of the other 80 chemicals in cannabis, does not give the "high" typically associated with THC. Nor does it appear to cause harm to the heart.

In fact, studies reviewed by the medical group showed possible links to lower blood pressure, reduced heart rate and less inflammation, which is an underlying culprit of the narrowing of the arteries that can lead to heart disease and strokes.

However, despite the hundreds of products currently being sold over the counter and online, there is only one CBD-derived product approved by the US Food and Drug Administration, the group wrote.

'Urgent' need for in-depth research

There is one caveat to all these research findings: Existing studies on marijuana and the heart are "short-term, observational and retrospective studies, which identify trends but do not prove cause and effect," Page said.

There is an "urgent" need for "carefully designed, prospective short- and long-term studies regarding cannabis use and cardiovascular safety," Page added.

But that's tough to do in today's climate, because marijuana is classified as a Schedule I controlled substance by the US Drug Enforcement Agency. That limits research dramatically, and the DEA should remove those restrictions so that scientists can better study marijuana's effects, the group advised.

In addition, the medical group recommended cannabis to be part of the US Food and Drug Administration's tobacco control and prevention efforts, which may mean that there would be age restrictions on who can purchase weed, retailer regulations and even excise taxes.

The American Heart Association is looking over the scientific statement and will be releasing new policy updates in coming weeks, according to Michelle Kirkwood, an AHA spokesperson.

"The public needs fact-based, valid scientific information about cannabis's effect on the heart and blood vessels," Page said.

"Research funding at federal and state levels must be increased to match the expansion of cannabis use -- to clarify the potential therapeutic properties and to help us better understand the cardiovascular and public health implications of frequent cannabis use."