A Case Report and Literature Review: Chlorhexidine-induced anaphylaxis in a hemodialysis patient.

Chlorhexidine is a widely used antiseptic in healthcare settings, particularly for catheter site preparation in hemodialysis patients. While generally considered safe, chlorhexidine can rarely cause severe IgE-mediated anaphylactic reactions. Here we report the case of a 47-year-old man on maintenance hemodialysis who experienced two episodes of severe allergic reactions during dialysis sessions. During the first episode the patient presented with dyspnea, hypotension, and pruritus, which we initially attributed to the dialyzer membrane reaction. After changing the dialyzer membrane, the patient remained asymptomatic for 19 sessions. However, a second, more severe episode occurred with urticaria, profound hypotension, and respiratory distress requiring intravenous adrenaline. Retrospective analysis revealed chlorhexidine antisepsis at the tunneled catheter site as the causative agent, confirmed by elevated serum IgE (285 IU/mL), with complete resolution after switching to povidone-iodine as an antiseptic instead. This case demonstrates a concept called "sensitization window" where compromised skin integrity at the catheter exit site facilitated chlorhexidine penetration despite three years of uneventful exposure of the same during fistula use. This case highlights the importance of considering chlorhexidine hypersensitivity in such unexplained dialysis-related allergic reactions. Early recognition and prompt antiseptic substitution are thereby crucial to prevent potentially fatal anaphylactic episodes in this vulnerable population.