Anaphylactic reaction to intraurethral chlorhexidine: sensitisation following previous repeated uneventful administration

Instillagel(®) (CliniMed, High Wycombe, UK) is commonly used in urethral catheterisation and to facilitate the passage of instruments into the bladder in urological practice. Its active ingredients include 0.25% chlorhexidine, 2% lidocaine, 0.06% methyl hydroxybenzoate and 0.025% propyl hydroxybenzoate. We discuss the case of an 84-year-old man who received intraurethral Instillagel(®) prior to laser ablation of a recurrent transitional cell carcinoma of the bladder, resulting in anaphylaxis. Subsequent investigation confirmed allergy to chlorhexidine. Although there are previous reports in the literature, this is the first report of intraurethral chlorhexidine resulting in anaphylaxis in a patient who had had repeated, uneventful previous exposures. As such, this case illustrates the phenomenon of chlorhexidine sensitisation and that previous uneventful exposures do not exclude the diagnosis of anaphylaxis in the context of sudden, unexpected deterioration.