Although Chinese herbal medicines (CHM) are generally considered to be safe and effective, a considerable number are found to have caused adverse effects. So long as CHM are largely untested for their quality and safety, there are always risks of drug adulteration, drug interaction, and contamination with toxic substances in these products. False and misleading labels can also be problems with CHM sold over the counter (e.g., McCormick, 2000; Nortier et al., 2000). In some clinical studies, proper identification and accurate dosage of the Chinese herbs used were not given (e.g., Wong et al., 1999).

Chinese patent medicines typically contain several active ingredients including primarily herbs, animal parts, and minerals. These patent products are usually formulated into pills, tablets, powders, or liquids for ease of use. Heavy metals or unapproved ingredients thus could be introduced into some of these medicines during formulation. In some cases, pharmaceutical adulterants were found added to enhance or speed up treatment efficacy.

Arsenic, cadmium, lead, and mercury are the heavy metals often found in some CHM. These contaminants might have come from pesticide applications during cultivation of herbs, from soil, or from processing machinery used in manufacturing plants (e.g., Dharmananda, 2002; Espinoza et al., 1995; Fratkin, 1997; Kang-Yum and Oransky, 1992; McCormick, 2000). Drugs like aminopyrine, caffeine, ibuprofen, and salicylamide are some of the adulterants found in some CHM used for treatment of asthma, back pain, or arthritis (e.g., Fratkin, 1997; Huang et al., 1997; Ries and Sahud, 1975).