Is there a risk of sensitization and allergy to chlorhexidine in health care workers?

Background: In Denmark, chlorhexidine is the standard disinfectant in most hospitals and health care workers are repeatedly exposed to it. The aim of this study was to establish whether there is a risk of sensitization and allergy to chlorhexidine from this type of exposure. Methods: Two hundred and forty-eight doctors, nurses and auxiliary staff were invited to participate in the study. One hundred and four individuals took part in the full study including skin tests and a questionnaire and a further 74 individuals filled in the questionnaire giving a total of 178 questionnaires (72%). Patch tests with chlorhexidine gluconate 1% and chlorhexidine acetate 1% were performed looking for type IV (delayed type) allergy. A prick test with chlorhexidine gluconate 0.5% and an intradermal test with chlorhexidine 0.0002% were performed looking for type I (immediate type) allergy. Results: There were no positive tests in any of the 104 individuals tested (99% confidence interval 0-4.9%). There was a predominance of females in both groups and the overall median age was 42 years (28-63). No one in the group not tested reported to have a verified or suspected allergy to chlorhexidine. Conclusion: In this first study to examine the risk of type I and type IV allergy to chlorhexidine in health care workers with daily exposure to chlorhexidine, we did not identify allergies to chlorhexidine in any of the 104 individuals tested or in the additional 74 individuals who completed the questionnaire. We conclude that an allergy to chlorhexidine in health care workers is likely to be rare.