A multidisciplinary approach to the toxicologic problems associated with the use of herbal medicines

In Hong Kong, a multidisciplinary team consisting of a pharmacist, a chemical pathologist, a scientific officer, and a physician has jointly provided an advisory service on herbal safety to healthcare professionals of all public hospitals since August 2000. This paper reports the first 2 years of experience of this team to emphasize the importance of a multidisciplinary approach to herbal poisoning. Twenty referrals received from the public hospitals from August 2000 to June 2002 were reviewed. The diagnosis of herbal toxicity was made after consideration of the temporal relationship between exposure to the herb and the occurrence of the adverse event and the exclusion of other causes. The causal relationship was seen as much stronger if the herb's pharmacological effects could fully explain the adverse event, if there were similar previous reports, and if the toxicological analysis findings were supportive. In 10 patients, the adverse events were deemed unlikely to be related to the use of herbal medicines. In 3 patients, it was concluded that the adverse events were possibly related to the use of herbal medicines. In 7 patients, the causal relationship was seen to be much stronger because the adverse events in these patients simply reflected the pharmacological effects of the herbs consumed and specific toxic ingredients were isolated from herbal residues and patients' urine or serum. The clinical problems arising from the use of herbal medicines included the Aristolochia species causing acute renal failure (n = 1), aconite roots causing aconitine poisoning (n = 2), the Datura species causing anticholinergic poisoning (n = 1), and "yulan" (Stephania sinica) causing tetrahydropalmatine poisoning (n = 3). The 4 patients with acute renal failure and tetrahydropalmatine poisoning received these toxic herbs, which were not listed in the prescriptions, as a result of poor dispensing practice or for other reasons. Toxicological problems associated with the use of herbal medicines are complex and may be easily overlooked. A multidisciplinary team of experts should be made available to provide advice to frontline healthcare professionals.