Tell the pharmacist, for example, 'I'm taking St. John's wort. Medications that are used to treat HIV infection, epilepsy, and heart disease may be particularly influenced by dietary or herbal supplements, says Burstein. Also noteworthy are medicines and supplements that work on the same organ system or disorder. For example, if someone is taking a mood-enhancing drug for depression, taking St. John's wort may add to the effects of this drug, which may not be particularly good. Another example is gingko biloba and garlic, both of which thin the blood.
Purity is also an issue with any supplement.
For further information on these agents, there are a few sources. Burstein also highly recommends the Natural Medicines Comprehensive Database . This web site contains a series of monographs on more than 800 herbal preparations, with information on safety, drug interactions, and how the compounds work. The site is geared more toward the physician, however, and does require a subscription. All rights reserved.