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Surprising Side Effects of Marijuana, Says Science

It can help...and hurt.

In recent years, marijuana has skyrocketed in acceptance, both legally and in public sentiment. These days, 91% of Americans believe it should be legal for both medicinal and recreational use, and recreational marijuana is legal in 19 states. Although pot isn't the demonized illicit drug of the past—today we know it's relatively safe to use—it's not entirely without risks you should know about, especially if you have certain health conditions. Read on to find out more—and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had COVID.


Mental Health Issues

Woman looking into distance.

Marijuana is a well-reputed relaxant. But for some people, it can have the opposite effect, causing anxiety, paranoia, and even panic attacks, the CDC says. "Marijuana use can cause cognitive impairment and should be used with caution if you have a mental health condition," warns the Mayo Clinic. "Marijuana use might worsen manic symptoms in people who have bipolar disorder. If used frequently, marijuana might increase the risk of depression or worsen depression symptoms." 


Heart Trouble

Man With Heart Attack

Also surprising for a renowned chill-out drug: Smoking marijuana can increase blood pressure and heart risk. "Marijuana raises heart rate for up to three hours after smoking," says the National Institute on Drug Abuse (NIDA). "This effect may increase the chance of heart attack. Older people and those with heart problems may be at higher risk."

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Cannabinoid Hyperemesis Syndrome (CHS)

Woman Suffering From Nausea

Another one of pot's contradictions: It's prescribed to some people to relieve nausea, but some heavy marijuana users experience severe queasiness, vomiting, and stomach pain. It's called cannabinoid hyperemesis syndrome, or CHS. Experts estimate 2.7 million Americans experience the condition, which is frequently misdiagnosed. (Last year, it was the subject of a "Medical Mysteries" column in the Washington Post.) "CHS went from being something we didn't know about and never talked about to a very common problem over the last five years," Dr. Eric Lavonas, a spokesman for the American College of Emergency Physicians, told the New York Times. It has a simple cure: Stop smoking pot.

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Trouble Breathing

Young man having asthma attack at home

Just like smoking tobacco, toking marijuana involves inhaling smoke, which can affect your breathing. "Marijuana smoke irritates the lungs, and people who smoke marijuana frequently can have the same breathing problems as those who smoke tobacco," says the NIDA. "These problems include daily cough and phlegm, more frequent lung illness, and a higher risk of lung infections." Unlike tobacco, the agency points out, marijuana has not been found to increase the risk of lung cancer.

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Risky Behavior

tired woman driver

Not to sound like Reefer Madness, but a 2017 study found that marijuana users 50 to 64 years old were more likely to participate in risky activities—including impaired driving, stealing, and physical violence—compared to older nonusers. Other studies have found that marijuana users 65 years or older were more likely to drive under the influence compared to older adults who don't use pot.

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Drug Interactions

Closeup of a young brunette getting some aspirins from a bottle at home.

According to the Mayo Clinic, marjiuana can cause side effects when mixed with other medications. These include increasing the risk of bleeding, lowering blood pressure, reducing the effects of antivirals, increasing sedative effects of certain drugs, and affecting blood sugar levels. That may make marjuana use riskier for people taking anticoagulants or medications for chronic conditions like blood pressure, HIV and diabetes. And to get through this pandemic at your healthiest, don't miss these 35 Places You're Most Likely to Catch COVID.

Michael Martin
Michael Martin is a New York City-based writer and editor. Read more about Michael