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Five Supplements You Should Never Take, According To Experts

These over the counter supplements should be avoided at all cost.
FACT CHECKED BY Emilia Paluszek

The supplement market has never been so diverse—there seems to be an over-the-counter pill available for everything from weight loss to sexual dysfunction. But just because a product is available and marketed as "all-natural" is no guarantee that it works, or, more importantly, is safe.

"The problem that we've had recently in recent years, especially, is that there's been an explosion of new ingredients," says Pieter Cohen, MD, associate professor at Harvard Medical School and an internist at Cambridge Health Alliance. "So it's not only that we're worried about the ingredients that are legal and permitted and supplements are historically used in supplements for many, many years. So there are many of these ingredients, these are individual compounds found in botanicals or other substances that can pose health risks. But nowadays we're seeing so many new innovations or brand new ingredients being introduced to supplements. Again, because the FDA isn't vetting these products before they show up on store shelves or on the internet, what happens is that they can pose unpredictable risks. So we need to work on reform. We need to work on ways to strengthen the FDA's ability to limit what comes on to the market, to have a safety gauge, to make sure that dangerous, potentially dangerous, products don't appear in store shelves. And when they do that, they can rapidly be taken off the market. So we're really going to need to see a lot of changes in order to deal with this very actively evolving health care products."

"Because the FDA does not approve dietary supplements before they are marketed, the agency often does not know when new products come on the market," the agency states. "Therefore, we are not able to keep a complete list of all dietary supplements sold in the United States. If you want more detailed information about a specific dietary supplement than the label provides, we recommend that you contact the manufacturer of the product directly. The name and address of the manufacturer or distributor can be found on the label of the dietary supplement." Here are five supplements known to cause harm to your health, according to experts. 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

Woman holding packs of pills and measuring tape in hands.

Weight loss supplements come under many different names—fat burners, diet pills, metabolism boosters, and so on. What they generally have in common is a lack of clinical trials and, at worst, seriously dangerous side effects. ​​"A product isn't necessarily safe simply because it's natural," warns the Mayo Clinic. "Though rare, some dietary supplements have been linked to serious problems, such as liver damage. Supplements can have strong effects. Ephedra (ma-huang) is an herb once used for weight loss. It's now banned by the FDA because it was associated with adverse effects, such as mood changes, high blood pressure, irregular heart rate, stroke, seizures and heart attacks. Some weight-loss supplements have been found to contain hidden ingredients, such as prescription drugs, that may be harmful."

The May 2022 issue of AMA Journal of Ethics focuses on the potential harm of unregulated weight loss supplements. "Weight loss and management are challenging in our current environment of readily available energy-dense foods and a sedentary lifestyle," the authors wrote. "Telling the patient to 'eat less and exercise more' does not work. Almost any diet that reduces energy intake will produce weight loss if followed. Explaining dynamic energy balance and the many factors that contribute to one's body weight will help reduce patients' guilt about past weight loss failures. Clinicians should emphasize moderate, achievable weight loss and health goals and the importance of lifelong healthy lifestyle changes over quick, dramatic weight loss."


Caffeine Pills

too much caffeine

Caffeine pills can be very dangerous if taken in excess. "Pure and highly concentrated caffeine products present a significant public health threat and have contributed to at least two deaths in the United States," says the FDA. "In recent years, dietary supplement products consisting of pure or highly concentrated caffeine in powder and liquid forms have emerged on the market. These products are often marketed in bulk packaging with up to thousands of servings per container, requiring the consumer to measure out a safe serving from what can be a toxic or even lethal amount of bulk product."

People may not realize that what might seem to be a tiny amount of powder could cause serious harm. "The difference between a safe amount and a toxic or life-threatening amount of caffeine in these highly concentrated products is very small," the FDA statement continues. "Safe quantities of these products can be difficult or nearly impossible to measure accurately with common kitchen measuring tools. For many of these products, volume measures such as teaspoons are not precise enough to calculate how many milligrams of caffeine are in the recommended serving size. These products are also often sold in ways that increase the likelihood of accidental measurement error. Just one teaspoon of pure powdered caffeine can contain the same amount of caffeine as 28 cups of coffee, and a half cup of a liquid highly concentrated caffeine product contains the equivalent of more than 20 cups of coffee. These are toxic amounts that can have serious health consequences.


Male Sexual Enhancement Supplements

Sad man sitting on a bed, girlfriend in the background.

The FDA recently warned against over 50 male sexual enhancement/weight loss pills after discovering they contained unlisted ingredients. "The FDA purchased these products on Amazon and eBay and agency testing found that the products contain active pharmaceutical ingredients not listed on their labels, including some with ingredients found in prescription drugs," an FDA statement reads. "These products may cause potentially serious side effects and may interact with medications or dietary supplements a consumer is taking."

The FDA found ingredients including sildenafil, tadalafil, vardenafil, sibutramine, desmethylsibutramine, phenolphthalein and/or fluoxetine in the supplements. "Protecting the health and safety of Americans is the FDA's highest priority, and we will remain vigilant and communicate about products and companies that place U.S. consumers at risk," said Donald D. Ashley, J.D., director of the Office of Compliance in the FDA's Center for Drug Evaluation and Research. "While the FDA has engaged in discussions with online marketplaces like Amazon and eBay regarding these issues in the past, we believe they can do more to protect consumers from these fraudulent and potentially dangerous products. We continue to urge stores, websites and online marketplaces, like Amazon and eBay, to take appropriate steps to protect the American public by not selling or facilitating the sale of illegal FDA-regulated products."


Heart Disease Supplements

doctor holding heart

The FDA recently warned seven companies for selling supplements marketed as being able to prevent or treat cardiovascular disease or related conditions, including atherosclerosis, stroke, or heart failure. "Given that cardiovascular disease is the leading cause of death in the U.S., it's important that the FDA protect the public from products and companies that make unlawful claims to treat it. Dietary supplements that claim to cure, treat, mitigate or prevent cardiovascular disease and related conditions could potentially harm consumers who use these products instead of seeking safe and effective FDA-approved treatments from qualified health care providers," said Cara Welch, Ph.D., director of the Office of Dietary Supplement Programs in the FDA's Center for Food Safety and Applied Nutrition. "We encourage consumers to remain vigilant when shopping online or in stores to avoid purchasing products that could put their health at risk."

"Studies have shown no benefit of taking multivitamins in reducing overall mortality, deaths from cardiovascular disease, or cancer-related deaths," says Jill Jin, MD, MPH. "Similarly, studies done specifically looking at supplementation with vitamin E, vitamin D, calcium, vitamin A, beta carotene, folic acid with or without vitamin B12, vitamin B3, vitamin B6, vitamin C, and selenium have not shown benefits in reducing overall mortality. For many supplements, though, the evidence is limited."


Nicotine Gummies

no smoking sign

The FDA is warning a manufacturer for ​​marketing illegal flavored nicotine gummies, a product which they believe could cause immense harm to children. "Nicotine gummies are a public health crisis just waiting to happen among our nation's youth, particularly as we head into a new school year," says FDA Commissioner Robert M. Califf, M.D. "We want parents to be aware of these products and the potential for health consequences for children of all ages – including toxicity to young children and appeal of these addictive products to our youth. The FDA will not stand by as illegal products infiltrate the marketplace."

"We remain unwavering in our use of compliance and enforcement resources to curb all unlawful marketing of tobacco products, especially those that youth could easily confuse with something that they consume regularly – like candy," says Brian King, Ph.D., M.P.H., director of the FDA's Center for Tobacco Products. "Today's action should be a wake-up call for manufacturers of these illegal products that the FDA is actively working to identify violations and to swiftly seek corrective actions."

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