A patch test study of 27 crude drugs commonly used in Chinese topical medicaments.

Chinese topical medicaments (CTMs) are commonly used in Taiwan and in Southeast Asia. However, a systematic evaluation of contact sensitization potential from CTM has not been carried out to our knowledge. This study was undertaken to investigate the incidence of contact sensitivity to the components of CTM in patients with contact dermatitis from CTM. A screening series of 27 crude drugs most commonly used in CTM as well as a modified European standard series was patch tested in 30 patients. The herbs with the most frequent positive reactions were Flos Caryophylli (see text), Radix Angelicae Pubescentis (see text), Cortex Cinnamomi (see text), Cortex Radix Acanthopanacis (see text), Caulis Impatientis (see text), Resina Draconis/Sanguis Draconis (see text), Fructus Cnidii (see text), Radix Gentiana Macrophyllae (see text), and Rhizoma Ligustici Chuanxiong (see text). Concomitant allergy to colophonium was found in most of these positive reactions. Reducing the concentration and simplifying the compositions of these components, as well as replacement with those of low allergenicity in CTM, such as Rhizoma Arisaematis (see text), Herba Lycopodii (see text), Radix Cyathulae Officinalis (see text), Rhizoma Pinelliae (see text), Radix Angelicae Dahuricae (see text), Herba Dendrobii (see text), Secretio Moschus (see text), and Stigmata Croci (see text), may be advocated. A precise labelling of the dosage of each component and the exact chemical compounds in CTM products could further improve the safety and therapeutic effects of CTM in the future.