P010 A hidden danger in common antiseptics: chlorhexidine anaphylaxis during routine medical procedures – a case series

Abstract

Chlorhexidine, a common antiseptic, rarely causes hypersensitivity, but perioperative reactions are increasing. Poor labelling and hidden sources delay diagnosis. We present a case series of eight patients (aged 30–75 years; five female and three male) who experienced immediate systemic reactions within minutes of exposure through cutaneous application to breached skin or mucosa in the context of invasive procedures, including perioperative procedures, intra-articular injections or vascular access (peripherally inserted central catheter insertion). All eight patients developed symptoms consistent with anaphylaxis shortly after exposure. Skin testing was positive in all patients: skin prick testing at 5 mg mL−1 was positive in one of eight, and intradermal testing at 0.002 mg mL−1 was positive in seven of eight. Specific IgE to chlorhexidine was positive in only one of eight, indicating limited sensitivity. Acute tryptase levels showed marked elevation in three patients (up to 72 µg L−1), one patient had normal acute tryptase, and in four patients the results were unknown. These cases underscore the importance of considering chlorhexidine as a culprit in perioperative anaphylaxis. Negative skin prick test or intradermal testing does not exclude diagnosis. According to the Danish Anaesthesia Allergy Centre, chlorhexidine allergy should be diagnosed based on a relevant clinical reaction in combination with diagnostic tests. The NAP6 study advises that both skin prick testing and specific IgE should be performed. Our findings support the sensitivity of skin testing, while specific IgE proved less reliable. Our findings support that cutaneous and mucosal application during invasive procedures represents an effective systemic exposure route, and routine inclusion of chlorhexidine in perioperative allergy investigations, together with strict avoidance strategies, is essential to prevent recurrent life-threatening reactions.