Toxicity and Interactions Issues in Chinese Herbal Medicine

Several recorded incidents of adverse reactions have occurred to Chinese herbs over the past 12 years. In most cases, the incidents have involved multiple patients consuming the same or similar substance, rather than isolated case reports. This is significant because it allows an opportunity to evaluate the common factors in these cases. Before proceeding, it is important to review the unique aspects of Chinese medicine (in contradistinction to Western herbal medicine) which are of relevance to understanding these issues.

general information:
Chinese medicine largely relies on formulae of eight to sixteen herbs, rather than single herbs, nutrients or drugs, as in common in Naturopathic and conventional medicine. While the number of total active constituents can thus be very high, the amount of any individual constituent is generally low. This is generally thought to minimize both side-effects and interactions in correctly prescribed formulae.

Chinese herbal formulae are prescribed as teas, powders, extracts and pills. Teas may have very large amounts of active ingredients, often beginning with raw material of more than 100 grams for a daily dose of decocted herbs in mainland China. Japanese Kampo practitioners often use much lower doses, with raw herb equivalents ranging from 30-45 grams per day. Yet even these lower end dosages are relatively large compared to about 0.5-10 grams per day used in typical practice of Naturopathic medicine and medical herbalism. Thus, misprescribed formulae may have high potential for side effects, independent of the inherent safety of the herbs they contain.

Chinese formulae of this size have been prescribed for 2000 years according to traditional Chinese parameters that match discrete symptom complexes or syndromes with specific herb combinations. The general rule of thumb is that an herb or formula will cause side effects if the disease is treated without consideration of the entire syndrome present.

Syndromes are basically just the differences between patients in terms of appetite, energy level, sleep, physical fitness and other general parameters. Many of the herbs in a large formulae for chronic illness address such general parameters rather than the specific pathology as defined by conventional biomedicine. Most of these general herbs are completely nontoxic, such as mild tonics like Astragalus or digestives, like ginger.

the written tradition:
Because the Chinese had widespread distribution of medical books by 800 C.E. (A.D.), they have had at least 1,200 years to vigorously debate the effectiveness of various herbs and formulae, as well as the safety and clinical validity of their diagnostic methods.

During the premodern era, the misuse of herbs was a constant concern to literate scholar physicians. Many important premodern medical texts have lengthy diatribes against prevailing medical malpractices. In most cases, these diatribes are directed at overall misdiagnosis or prescription without diagnosis. However, concerns have also been raised about toxic herbs like aconite or those that are easily abused, like tea, poppy and ginseng.

Many Chinese herbs are grown traditionally without pesticides and herbicides. About half of the standard materia medica are essentially weeds themselves. Another significant amount are wildcrafted. A smaller amount, especially the more valuable herbs, may be sprayed as necessary. Since Chinese herbs are exported to the U.S. as packaged food products, they are not directly fumigated at customs, though their packaging may be. However, contamination by such sources should remain a suspect in all future incidents, given China's apparent laxity at enforcing environmental and public safety regulations.

A number of Chinese herbs were traditionally derived from what are now endangered species. The endangered animals are not actually used in any legitimate clinics of oriental medicine in America. However, they may be available in products in Chinatown herb shops. Herbal medicines made from endangered plants are all sourced through cultivation; they are not taken from their wild habitat.

patent medicines:
Chinese herbs are frequently consumed in what are called patent or proprietary medicines. There are considerable legal, ethical and scientific problems with these prefabricated pill products and they should be avoided unless one is a fully trained professional in Chinese herbal medicine. In response to the apparent lack of quality control in Chinese patent medicines, several American manufacturers have set up production facilities in China which abide by strict quality control standards (GMP).

Most problems with Chinese herbs appear to arise from drug interactions, contamination or misidentification of herbal materials, drugs hidden in herbal products, heavy metal poisoning and acute allergic hypersensitivity. This suggests the greatest problem with Chinese herbs is lack of quality control and other regulations in production.

All incidents, except for one, described in this Herb Group involve the prescribing of Chinese herbs by untrained individuals or self-prescribing by consumers. That one appears to be an allergic reaction to a particular herb, which was probably unavoidable. This suggests the lack of training in the proper use of Chinese herbs to be a significant factor in the occurrence of adverse effects. The fact that fully trained practitioners of TCM are rarely, if ever, responsible for serious adverse herb reactions in their patients, suggests that traditional prescribing methods should be further investigated for their contribution to the safe use of Chinese Herbs.