Because the use of medicinal herbs and herbal products have become increasingly popular worldwhile it is essential to be aware of of their clinical and adverse effects. Herbal products are considered to be dietary supplements in some countries, therefore are subjected to a very limited form of regulation and oversight. Even though they are often promoted as natural and therefore safe, herbal products are by no means free from adverse effects. In fact several cases of intoxication and lethal side effects have recently been reported with herbal products including direct toxic effects, allergic reactions, effects from contaminants and interactions with drugs and other herbs. Little is known about the safety of herbal products compared to synthetic drug treatment. Herbal medicines must meet the same stringent criteria of quality, efficacy and safety as synthetic drugs and additional reseach is needed to define the pharmacology, stability, and bioavailability of these products.