Skip to content

These Supplements Can Be Dangerous, Says Pharmacist

If you see these at your local drug store, just leave them on the shelf.

Taking supplements can be a great, easy way to support your overall health. This is especially true if you have trouble getting all the nutrients you need from your diet, or if you have particular health conditions that create a need for an extra boost of certain vitamins or minerals. Supplements may be made of things other than vitamins or minerals, such as herbs, plant extracts and enzymes.

 Dietary supplements differ from prescription medications in some important ways. The biggest of these is that supplements — which are available over the counter to whoever wants to buy them — aren't regulated by the Food and Drug Administration. The manufacturers themselves, not the federal agency, are responsible for ensuring that their products are safe and contain the amount of ingredients they say they do. That means, unfortunately, that sometimes supplements you can buy at the store could be ineffective, or could even contain too much of an ingredient, leading to dangerous effects.

 Here are four supplements that can be dangerous in certain formulations or quantities. If you see these at your local drug store, just leave them on the shelf. 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.



Tired African-American man having headache after hard day, feeling exhausted

Aconite is an herbal remedy that's been used for thousands of years to treat a number of conditions, including joint pain, fever and inflammation. Aconite quickly impacts your nervous system and heart, and when it's not taken properly, can have very serious effects. That includes nausea, vomiting, fast or irregular heartbeat, muscle dysfunction, breathing difficulties, convulsion, shock and coma, research shows. Eating the plant or misusing aconite supplements has killed people before and is also dangerous in lotion or cream form.





Yohimbe is marketed to enhance sexual and athletic performance and as a weight loss aid. The active ingredient, yohimbine, comes from the bark of an African tree. Yohimbine is used in some prescription drugs for erectile dysfunction, but supplements are supposed to be made from extracts of bark, not the pharmaceutical version of yohimbine, according to the National Institutes of Health (NIH). A 2016 study of 49 yohimbe supplements sold at major chains in the U.S. found that 39% were made from non-natural or highly processed sources. Less than a quarter of the products actually contained the amount of yohimbine that was stated on the bottle. Some contained nearly one-and-a-half times more of the ingredient than was reported on the label.

 Yohimbe can cause stomach problems, rapid heartbeat, anxiety and high blood pressure. Because of the dangers, yohimbe is banned in several countries including Canada, Australia and the United Kingdom.




kava kava supplement capsules on brown wooden plate
Shutterstock / Iryna Imago

Kava is a root, which has been used for centuries, usually in teas. It's been said to leave a feeling of calm and is often used for anxiety, trouble sleeping or as stress relief. It is also available in supplement form. There is evidence that kava can be an effective treatment for anxiety, but the benefits are not worth the risks. Along with upset stomach, headache, dizziness and other side effects, kava has also been connected to liver injuries, even fatal ones. Using this supplement long-term can also cause a condition known as kava dermopathy, where the skin turns yellow and flaky.





Comfrey is a medicinal plant that has been used for more than 2,000 years to help wounds heal and to soothe aching and bruised muscles. Research shows that it can work as a pain reliever and to cut down on healing time when used on the skin. But there is also plenty of evidence that it can cause serious liver damage and cancer. While pills containing comfrey have been banned in the United States and other countries, comfrey can still be found in creams and ointments (as well as in teas and oils). Comfrey is not only dangerous to ingest, but products made from using the plant can also be absorbed through the skin. That means even using comfrey in creams or lotions can be harmful, especially if you use it for longer periods of time.



Final Word From the Doctor

Doctor explaining the bottle of pills to patient in the office at desk

It's important to remember that just because something is natural doesn't mean it's safe. You should always talk to your doctor or pharmacist first before taking a supplement. Your doctor can help you determine if there is any benefit, or harm to the supplement, including if it will interact with any medications you're taking.

Dr. Shaili Gandhi, Pharm.D., is the vice president of formulary operations at SingleCare

Shaili Gandhi, PharmD
Shaili Gandhi, PharmD, is Vice President of Formulary Operations at free prescription savings service SingleCare. Read more about Shaili