Paracetamol is a ubiquitous analgesic and antipyretic that is widely administered, including by anaesthetists. Immediate hypersensitivity reactions to intravenous paracetamol are particularly rare. We report two cases involving four separate episodes of anaphylaxis to intravenous paracetamol in different perioperative settings without a past history of intolerance to the oral form. The allergological investigations are described, during which it became evident that both patients were allergic to an excipient (mannitol) present in the formulation and that neither was allergic to the principal agent (paracetamol). The importance of referral and investigation of perioperative drug reactions is underscored by these two cases.

We present a case of anaphylaxis to suxamethonium and/or vecuronium in a patient who had previously suffered an anaphylactic reaction, presumably to rocuronium. The patient had not been referred for formal allergy testing after the first anaphylactic reaction. Subsequent formal allergy testing revealed sensitivities to suxamethonium, rocuronium and vecuronium. Her next anaesthetic, using cisatracurium, was uneventful. It is recommended that all patients with suspected perioperative anaphylaxis are referred for testing. This is the responsibility of the anaesthetist. Particular caution should be used with suspected neuromuscular blocking drug allergy as cross-reactivity is common and not predictable by drug structure.

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