Allergic contact dermatitis to chlorhexidine.

Chlorhexidine is a commonly used antiseptic agent in the health-care setting. Although exposure to chlorhexidine is very common, allergic contact dermatitis (ACD) is rarely reported. We report a case series of ACD to chlorhexidine in health-care workers and discuss our rates of allergy to chlorhexidine, from patch-testing performed at the Skin and Cancer Foundation, Melbourne, Australia. Of 7890 patients patch-tested, 840 patients were tested to 0.5% chlorhexidine diacetate with 28 (3%) positive reactions, 13 (2%) of which relevant to their presenting dermatitis. Altogether 1565 patients were tested to 0.5% chlorhexidine digluconate, with 47 (3%) positive reactions, 16 (1%) of which were relevant. We estimate our rate of relevant chlorhexidine ACD from our total clinic patients, non-occupational and occupational, to be at least 19/7890 (0.24%). Our rate of relevant chlorhexidine ACD in health-care workers is 10/541 (2%). Interestingly, our rates of chlorhexidine allergy are slightly higher than documented elsewhere. This raises the possibility that chlorhexidine is underestimated as an allergen worldwide, and should be tested for in health-care workers where there is a history of exposure.