Perhaps you’re the type of health nut who takes four or five different vitamin concoctions each morning to support weight loss, anti-aging, good digestion, clear skin and high energy. Or maybe you’re just curious about the medicinal effects of black tea, cranberry juice and licorice. Well, you’re in for a treat. The NIH has put together a very good database of the results of numerous studies about natural remedies, detailing the demonstrated effects on the human body, recommended doses and contraindications.

Many Americans believe that just because a capsule or tincture comes from a health food store and is filled with plant-derived ingredients, it’s safe. But “natural” doesn’t equal “good for you.” (Consider the effects of belladonna, which can be used to treat eye diseases—or as a lethal poison). Plants can contain potent chemicals that might interact with your prescription medications in unexpected ways.

Feeling blue and considering taking St. John’s wort? Do a little research before popping a pill. Turns out the “happy herb” can interact badly with SSRI antidepressants, birth control, antibiotics, chemotherapy drugs… and even Imodium.