Consumers are warned not buy or use the proprietary Chinese medicine Tian Sheng Yi Bao which has been found to have contained undeclared Western drug ingredients that may cause serious side effects.

The Department of Health said tests revealed the product contained glibenclamide and phenformin - Western drug ingredients used for treating diabetes.

Glibenclamide may cause nausea and gastro-intestinal upset and improper use may cause a significant fall in blood sugar levels with serious health consequences. Products containing glibenclamide ingredients must be registered before sale and can be sold only on a doctor's prescription and under a pharmacist's supervision.

Phenformin is associated with high incidence of lactic acidosis - a buildup of lactic acid in the blood - which can be fatal. The drug was banned in Hong Kong in 1985.

The department has no record of the product having been imported into Hong Kong for sale. As a precautionary measure, people who have been using the product should seek advice from healthcare professionals. Patients with diabetes should consult doctors for appropriate advice or medication.

People should dispose of the product or send it to the department's Pharmaceutical Service on 3/F, Public Health Laboratory Centre, 382 Nam Cheong Street, Kowloon.