The Supplements You Should Stay Away From

You can walk into a drugstore and buy any supplement you’d like. But that doesn’t mean taking it would be a good idea for you—even if your buddy swears by it.

Just like prescription meds, a supplement that provides health benefits to one guy can prove ineffective or even dangerous for another, says Matilde Parente, M.D., author of Healing Ways: An Integrative Sourcebook.

Everything from your overall health to your prescription meds to the way your body breaks down drugs can change the way a supplement works for you, says Bill Gurley, Ph.D., a chemistry professor at the University of Arkansas for Medical Sciences.