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Studies Warn of These Marijuana Side Effects

Five cannabis side effects you need to know about.
FACT CHECKED BY Emilia Paluszek

Marijuana—also known as cannabis or weed—has gone from a federally illegal drug to becoming a fairly mainstream method of dealing with everything from pain management to mental health disorders—but doctors are worried about potential side effects. "In the world of healthcare, a medication is a drug that has endured extensive clinical trials, public hearings and approval by the U.S. Food & Drug Administration (FDA). Medications are tested for safety and efficacy. They are closely regulated, from production to distribution. They are accurately dosed, down to the milligram. Medical marijuana is none of those things," says Paul Terpeluk, D.O., Medical Director of Cleveland Clinic's Employee Health Services. Here are five side effects of marijuana experts want you to be aware of. Read on—and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had COVID.


Anxiety and Depression

Depressed young woman sitting on floor at home

Although marijuana has been used as a treatment for anxiety and depression, a recent study shows that not only does marijuana not work in treating mental health disorders, it could actually double the risk of addiction. "We learned there can be negative consequences to using cannabis for medical purposes," says lead author Jodi Gilman, of the Center for Addiction Medicine at MGH. "Our study underscores the need for better decision-making about whether to begin to use cannabis for specific medical complaints, particularly mood and anxiety disorders, which are associated with an increased risk of cannabis use disorder." 


Lung Issues

Research shows that long-term cannabis use can negatively impact lung health in a different way to tobacco. "Although the effects of cannabis were detrimental, the pattern of lung function changes was not the same. The research found that prolonged cannabis use led to over-inflated lungs and increased the resistance to airflow to a greater extent than tobacco," says Professor Bob Hancox. "Although cannabis is one of the world's most widely used drugs, there has been little research on the effects on the lungs. This is because it has been difficult to study a drug that remains illegal in most parts of the world. Of course, people who smoke both cannabis and tobacco are likely to suffer lung damage from both substances."

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Permanent Brain Changes

woman in a couch with headache and a hand on forehead

Marijuana use in adolescents can result in permanent changes to the brain, studies show. "There are a lot of open questions about the long-term effects of marijuana," says Susan Weiss, PhD, director of the division of extramural research at the National Institute on Drug Abuse (NIDA). "But there's a growing literature, and it's all pointing in the same direction: Starting young and using frequently may disrupt brain development." Persistent drug users were shown to have a drop in IQ of approximately six points. "That's in the same realm as what you'd see with lead exposure. It's not a trifle," Weiss warns.

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Heart Issues

Young woman suffering from breathing problem near window indoors.

Studies have shown that marijuana could negatively impact the heart and blood vessels, leading to a possible increased risk of heart attacks and heart failure. "Attitudes towards recreational and medicinal use of cannabis have changed rapidly, and many states have legalized it for medical and/or recreational use. Health care professionals need a greater understanding of the health implications of cannabis, which has the potential to interfere with prescribed medications and/or trigger cardiovascular conditions or events, such as heart attacks and strokes," said Robert L. Page II, Pharm.D., M.S.P.H., FAHA.

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The Impact On Parenting

new mom smiling with her newborn

Using marijuana does not necessarily make you a more relaxed parent: One study showed that parents who used cannabis were more likely to administer discipline techniques compared to non-users. "The acceptability of marijuana is growing in the United States and with that, more parents feel free to use the drug, sometimes even in front of their children," says Bridget Freisthler, professor of social work at The Ohio State University. "Some parents claim it makes them a better, more relaxed parent, but that may not be the case. Marijuana use is not risk-free. It affects a lot of behaviors, including parenting."

Ferozan Mast
Ferozan Mast is a science, health and wellness writer with a passion for making science and research-backed information accessible to a general audience. Read more about Ferozan
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