Ginseng is a perennial herb widely used in China, Japan, and Korea. It is also one of the mostcommonly used herbal medicines in the U.S. Although it is generally considered safe to use,adverse effects associated with ginseng use have been reported. Inappropriate ginseng use, suchas high dose administration, may cause insomnia, headaches, diarrhea, as well as cardiovascularand endocrine disorders. Other factors that may contribute to adverse effects of ginseng includethe variety of ginseng species, variability in commercial ginseng preparations, and potentialginseng-drug interactions. To minimize adverse effects of ginseng, consumers should be advisedto use it appropriately, and the herbal industry should try to provide standardized ginsengpreparations.