An overview of the toxicology of commonly used traditional Chinese medicine

Traditional Chinese medicine (TCM) plays an important role in health care systems in many parts of the world. Recently, interest in TCM has revived due to the rediscovery of the potential of TCM and natural products in new drug development. There is a general perception that TCM lacks systematic pharmacological, toxicological, and clinical studies. The deficiency in efficacy and safety has been a major hindrance to the progress of TCM, despite the success of herbal medicine in treatment of diseases for which the orthodox drugs in western medicine are ineffective. This brief review aims to serve as an introduction and a reference guide to TCM toxicology. The review summarizes the toxicity of some commonly used TCMs in terms of acute, systematic, genetic, analytic, and clinical toxicology. Acute toxicity study has shown that herbal medicines and their chemical constituents exhibit LD₅₀ values ranging from the practically nontoxic to supertoxic categories. Target organs of TCM toxicity include liver, kidney, gastrointestinal tract, nervous, and cardiovascular systems. TCM shows mutagenicity in the Ames test and increases the incidence of unscheduled DNA synthesis, micronucleus formation, and chromosomal aberration in cytogenetic assays. Some TCM products are contaminated with pesticides and heavy metals and adulterated with drugs of western medicine. Improper dispensing and use of TCM and individual idiosyncracy may result in adverse effects and fatality. Future TCM research, new drug development, and safety evaluation require adequate toxicity testing and mechanistic toxicology studies.