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Surprising Side Effects of 5 Popular Supplements

Buyer beware when it comes to these supplements.
FACT CHECKED BY Emilia Paluszek

When it comes to over-the-counter vitamins and supplements, how do you know which ones work and which are not worth the money (or worse, actually dangerous)? "While the Food and Drug Administration (FDA) is charged with overseeing dietary supplements, there is no safety testing or FDA approval required before a new supplement goes on the market," says Susan Farrell, MD. "In addition, there are no requirements that dietary supplement packaging list potential adverse effects, nor are there standards for maximum pill size (a clear risk for older people)." Here are the surprising side effects of five popular supplements. Read on—and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had COVID.


Weight Loss Supplements

weight loss

Weight loss supplements are big business, but can be very dangerous, experts warn. "Most people think this is going to be a quick fix and that is not the case," says celebrity fitness expert Sarah Louise Rector, founder of the SLR Life Workout Program and app. "Mentality-wise this can be very disheartening, and people can become even more affected with mood swings and negative body image. Most of the time people don't actually read the side effects that can occur when taking these types of supplements: An increase in blood pressure, insomnia, and problems for the liver can be some major side effects when taking weight-loss supplements."



selenium supplement tablets

Taking too much selenium can be hazardous to your health, experts warn. "Selenium is an element necessary for normal cellular function, but it can have toxic effects at high doses," reads a paper published in JAMA Internal Medicine investigating selenium poisoning. "Toxic concentrations of selenium in a liquid dietary supplement resulted in a widespread outbreak. Had the manufacturers been held to standards used in the pharmaceutical industry, it may have been prevented."


Liver-Cleansing Supplements

woman holding liver

"The whole appeal of this detox market, these teas, these juices, these cleanses is this desire for magical thinking," says toxicologist Ryan Marino, MD. "People want something that'll fix a problem, and if you can buy it online, take a pill every day, there's definitely some sort of element of wanting to believe that that'll be a magical cure all. The only thing you need to detox your body naturally, and I hate to even say that because I don't think anyone really does need to detox, is just your liver and your kidneys. And if those aren't working you should seek medical attention anyways."

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collagen supplements

If you're using collagen supplements for joints and cartilage health rather than just your skin, you might be wasting your money. "Many types of supplements that claim to promote cartilage restoration and healthy joints have been tested extensively. There is no evidence, that we can measure, that they do anything," says orthopedic surgeon Beau Konigsberg, MD. "Unfortunately, they are often expensive and without benefit. Someday there will be a breakthrough in cartilage restoration and growth but at this point there is nothing reputable on the market. I don't recommend collagen supplements for joint pain, but it's harmless if someone chooses to use it."

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Smiling woman taking a pill.

Perhaps the most surprising side effect of taking multivitamins is that they may not have much benefit at all. ​​"So many of my patients tell me they know their diet is not great but that I should not worry because 'at least' they take a multivitamin," says dietitian Anna Taylor, RD. "But multivitamins aren't a surefire way to get what you need." 

"Ask yourself, 'Am I doing everything possible to optimize my overall health before taking a multivitamin and/or supplement?'" says Raul Seballos, MD. "Smart lifestyle choices are your best guarantee of future health."

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