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Surprising Side Effects of Marijuana, Says Science

Read on for side effects you might not expect.
FACT CHECKED BY Emilia Paluszek

For decades, marijuana was demonized; today, the pendulum of social opinion on pot has swung sharply in the other direction. About 1.4 million people in the U.S. take marijuana for medical reasons, and a majority of Americans believe marijuana should be legalized for both medical and recreational use. But, experts say, pot's widespread social acceptance doesn't mean it isn't still a drug that can have physical consequences. Recent studies have found that marijuana use can have side effects that may surprise you. 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.


Marijuana May Help You Lose Weight

Woman measuring waist with tape standing in front of mirror.

Pot is infamous for increasing appetite, so reliably that it's sometimes used medically for that purpose. It may be surprising, then, that a 2019 study found regular recreational marijuana users are less likely to be overweight than non-users. Researchers from Michigan State analyzed health data from 33,000 people and found only 15% of "persistent" pot users were considered obese, compared to 20% of nonusers. "Over a 3-year period, all participants showed a weight increase, but interestingly, those who used marijuana had less of an increase, compared to those that never used," said the study's lead author, Dr. Omayma Alshaarawy.


Marijuana May Cause This Disorder

depressed Indian woman holding head in hands, sitting alone on couch at home

Scientists behind some recent studies warn that pot may not be as harmless—and medical marijuana may not be as widely beneficial—as believed. A study published last week by researchers at Massachusetts General Hospital found that people taking marijuana for medical reasons were nearly twice as likely to develop cannabis use disorder (CUD), and didn't find relief they sought from certain symptoms. "In this first study of patients randomized to obtain medical marijuana cards, we learned there can be negative consequences to using cannabis for medical purposes. People with pain, anxiety, or depression symptoms failed to report any improvements, though those with insomnia experienced improved sleep," said the study's lead author, Dr. Jodi Gilman.

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Marijuana May Make You Nauseated

Woman Suffering From Nausea

Marijuana is sometimes prescribed to relieve nausea, but some heavy users might experience the exact opposite effect. In cannabinoid hyperemesis syndrome (CHS), using cannabis can cause stomach pain, nausea, and vomiting that can be so severe they interfere with everyday life. Experts estimate 2.7 million Americans experience the condition, which is frequently misdiagnosed as stomach problems. "CHS went from being something we didn't know about and never talked about to a very common problem over the last five years," said Dr. Eric Lavonas, a spokesman for the American College of Emergency Physicians, in the New York Times

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Marijuana May Affect Your Brain

Doctor examines MRI scan of head, neck and brain of patient

Last month in the journal Stroke, the American Heart Association warned doctors that not enough is known about pot's effects on the brain, and they should have "balanced" discussions with patients about potential risks. That follows a number of studies which have found pot may harm the brain. One review published last January in the journal Addiction found that THC, the main psychoactive compound in marijuana, can negatively affect executive functioning, including the ability to plan, organize, solve problems, make decisions, and control emotions. 

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Marijuana May Cause Drug Interactions

Young Hispanic woman choosing between antibiotics or alternative medicine.

Two studies published last December found that smoking pot may lead to drug interactions—causing other medications you're taking to have a stronger or weaker effect than intended. Although cannabinoids, the active ingredient in marijuana, clear the body within 30 minutes, metabolites of marijuana can linger in the body for weeks, potentially affecting the liver and kidneys, which process medications. "Physicians need to be aware of the possibility of toxicity or lack of response when patients are using cannabinoids," said Philip Lazarus, the studies' senior author. "It's one thing if you're young and healthy and smoke cannabis once in a while, but for older people who are using medications, taking CBD or medicinal marijuana may negatively impact their treatment."

And to protect your life and the lives of others, don't visit any of these 35 Places You're Most Likely to Catch COVID.

Michael Martin
Michael Martin is a New York City-based writer and editor whose health and lifestyle content has also been published on Beachbody and Openfit. A contributing writer for Eat This, Not That!, he has also been published in New York, Architectural Digest, Interview, and many others. Read more about Michael
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