Acute allergic reaction after intravenous saline injection: an unusual presentation of chlorhexidine allergy.

A 63-year-old man presented to the emergency department after an episode of transient left hemiparesis and hemianaesthesia. His only history of allergy was an episode of mild urticaria after a postsurgical fentanyl infusion a few years previously. An intravenous cannula was inserted in his left cubital fossa. His neurological symptoms had resolved completely by the time he was reviewed by the neurology registrar. A magnetic resonance imaging brain scan was planned. The intravenous cannula was fl ushed with 10 mL of 0.9% normal saline after the rubber cannula connector was wiped with an alcohol-based swab. Within minutes, the patient experienced rapid development of generalised urticaria and periorbital oedema. He was treated with 25 mg of promethazine and 100 mg of intravenous hydrocortisone, with a good response. He had been fasting for 4 hours before this and was given no other medication.