Traditional herbal remedies are used by many patients for selfhealing. The potential risk of toxicity with herbal products is increased because they are not categorised as drugs (many of them are sold in health food stores and are designed as dietary supplements) and are, therefore, not subjected to standard tests for safety and effectiveness or good manufacturing practice standards that ensure quality control. Many herbal products are imported from foreign countries and often, like some domestic ones, do not have the active or inactive ingredients listed on the package labeling. Besides, many patients use herbal medicines along with standard drug therapy. Since a number of herbal preparations possess one or more pharmacologically active principles it is logical to suspect that many of these agents can interact pharmacodynamically and/or pharmacokinetically with prescription and over-the-counter pharmaceuticals. Recently, many reports dealing with adverse effects or toxicity of herbal products have been published.

In this review we present the characteristic examples of herbal products toxicity and their interactions with standard drugs and give some recommendations for overcoming this problem.