Contact allergic potential of topical traditional Chinese medicaments in Singapore

Abstract

Background: Western-based medication forms the basis of the health care system in Singapore. However, because Singapore is part of East Asia, there is still a high prevalence of use of topical traditional Chinese medicaments by the general population. Objective: This study was designed to determine the 10 most commonly used topical traditional Chinese medicaments by patients who were attending the Contact & Occupational Dermatoses Clinic. The final aim of the study was to put together a panel at the correct eliciting concentration for patch testing. Methods: Patients were interviewed and asked to identify the products that they had previously used from a panel of 74 medicaments. The 10 most commonly used topical traditional Chinese medicaments were then identified. Patients were then patch tested to these 10 preparations at concentrations varying from 1%, 5%, 10%, 20%, and 50% in each respective vehicle and as is. Results: No contact reaction was detected with five medicaments, but allergic contact reactions were detected with the other five preparations. These patients also had positive reactions to fragrance mix and/or balsam of Peru. Conclusions: Development of special panels for unique contact allergens in different regions with different social and cultural backgrounds is essential. Patients with positive reactions to balsam of Peru and fragrance mix should be advised against excessive use of topical traditional Chinese medicaments.