The relevance of chlorhexidine contact allergy.

BACKGROUND Chlorhexidine is used for disinfection of skin and mucosae in medicine and dentistry. Prolonged exposure may lead to contact sensitization and allergic contact dermatitis or stomatitis. OBJECTIVES The purpose of this study was to analyse the sources of chlorhexidine exposure and sensitization, and to obtain data on the prevalence of sensitization and chlorhexidine-related contact allergy. PATIENTS AND METHODS From 1999, patch testing was performed with chlorhexidine digluconate (0.5% aq.) on 7610 general dermatology patients with suspected contact allergy at the Turku University Hospital Dermatology Department. The medical records were reviewed concerning the patients' exposure to chlorhexidine. RESULTS A positive patch reaction to chlorhexidine was seen in 36 patients (0.47%). Current dermatitis or stomatitis caused by chlorhexidine-containing topical medicaments was seen in 5 patients. Chlorhexidine sensitization contributed to the current dermatitis in 11 patients. A history of earlier exposure to chlorhexidine-containing products was recalled by only 16 sensitized patients, whereas no exposure was revealed in 4 cases. CONCLUSIONS Chlorhexidine-containing corticosteroid creams, skin disinfectants and oral hygiene products are principal sources of chlorhexidine contact sensitization. Exposure to chlorhexidine in cosmetics may lead to delayed improvement of eczema in sensitized patients, emphasizing the importance of identifying the potential cosmetic sources.