Mercury and Chinese herbal medicine

In the October 2004 issue of BCMJ, the BC Centre for Disease Control reported marked elevation of blood mercury in two preschool aged children of Asian ethnicity with unusually high fish consumption.[1] They recommended physicians providing care for young children and women of childbearing age to inquire as to the frequency and species of fish consumed, and to measure blood mercury in individuals at risk of elevated blood mercury.

There is a recent report of acute generalized dermatitis, abnormal liver function, and elevated blood mercury level (187 nmol/L) associated with Chinese herbal medicine used for rheumatism by an 80-year-old Chinese patient.[2] The elevated blood mercury level returned to normal range upon discontinuation of Chinese herbal medicine, while his diet remained unchanged.

In the traditional Chinese medicine, Chinese herbal medicine, besides herbs, contains animal products and minerals.[3] The minerals include two mercurials, Zhu-Sha/Cinnabar (red mercuric sulfide) to bring longevity, and Qing-Fen/calomel (mercurous chloride) to detoxify various poisonous conditions.[4] Mercury as adulterant or contaminant in Chinese patent medicines of herbal origin has been well documented.[4-6]

The BC Medical Journal[1] and a review article[7] listed the various sources of mercury. They do not include Chinese herbal medicine or Chinese patent medicines of herbal origin.

About 12% of the US population used herbal medicine in 1997, a 380% increase from 1990.[8] Chinese herbal medicine and Chinese patent medicine, purchased in local Chinese herbal shops, are used increasingly by Chinese and other Asians, and by Caucasians as well.[9]

Allergic and adverse reactions have been reported in both Chinese and Caucasian patients seen locally.[2,10-13]

It is important for physicians to ask all patients about their use of complementary and alternative medicine. Blood mercury measurements should be considered in patients with dermatological, neurological, or renal abnormality[2] who are taking Chinese herbal medicine or Chinese patent medicine.

—H.C. George Wong, MD
Division of Allergy and Immunology, UBC,
Vancouver General Hospital,
Alternative therapies and allied health committee, BCMA


1. Copes R, Palaty J, Lockitch G. Mercury exposure in British Columbia: Do we have a problem? BC Med J 2004;46:390. Full Text 
2. Wong HCG. Acute generalized maculopapular eruption, abnormal liver function and elevated blood mercury level associated with Chinese herbal medicine. Can J Allergy Clin Immunol. 2002;7:92-96. 
3. Wong HCG. Chinese herbal medicine and allergy. ACI International. 2001;13:192-196. Abstract 
4. Kang-Yum E, Oransky SH. Chinese patent medicine as a potential source of mercury poisoning. Vet Hum Toxicol 1992;34:235-238. PubMed Abstract 
5. Espinoza EO, Bleasdell B. Arsenic and mercury in traditional Chinese herbal balls. N Engl J Med 1995;333:803-804. PubMed Citation 
6. Ko RJ. Adulterants in Asian patent medicines. N Engl J Med 1998;339:847. PubMed Citation 
7. Marshall L, Weir E, Abelsohn A, et al. Identifying and managing adverse environmental health effects: 1. Taking an exposure history. CMAJ 2002;166:1049-1055. PubMed Abstract Full Text 
8. Eisenberg DM, Davis RB, Ettner SL, et al. Trends in alternative medicine in the United States, 1990 - 1997: Results of a follow-up national survey. JAMA 1998;280:1569-1575. PubMed Abstract Full Text 
9. Wong HCG. Chinese patent medicines (Zhong Cheng Yao) of herbal and unknown origin used for allergic and other conditions. Can J Allergy Clin Immunol 2001;6:162-165. 
10. Wong HCG. Generalized allergic maculopapular eruption associated with Prostate Gland Pills, a Chinese proprietary medicine of herbal origin. Ann R Coll Physicians Surg Can 2000;33:104-106. 
11. Wong HCG. Acute urticaria associated with Chinese herbal medicine used for atopic dermatitis. Can J Allergy Clin Immunol 2001;6:77-79. 
12. Wong HCG. Allergic contact dermatitis from topical Chinese herbal medicine and generalized urticaria and angioedema from dietary supplementation: A case report. BC Med J 2002;44:184-187. Abstract Full Text 
13. Wong HCG. Cardiac adverse reaction associated with Fu Zi: A case of mild aconite poisoning from Chinese herbal medicine. Ann R Coll Physicians Surg Can 2001;34:358-361.     

H.C. George Wong, MD, FRCPC. Mercury and Chinese herbal medicine. BCMJ, Vol. 46, No. 9, November, 2004, Page(s) 442 - Letters.

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