PURPOSE OF REVIEW: Perioperative hypersensitivity reactions can pose diagnostic and management challenges for the anaesthetist. Difficulties in diagnosing hypersensitivity reactions in the perioperative setting are highlighted and recommendations from recent guidelines on the acute management of life-threatening anaphylaxis are presented. RECENT FINDINGS: Anaesthetists play a key role in investigating perioperative hypersensitivity reactions. During a suspected perioperative hypersensitivity event, a serum tryptase level should be measured to help with subsequent allergy investigation. Moreover, anaesthetists can ensure that a high-quality referral is made to allergy clinics by providing thorough documentation of the events, detailing symptoms, treatments, and the chronology of drug administrations. SUMMARY: Perioperative hypersensitivity reactions are rare but can be life-threatening. A high index of suspicion should be maintained for their successful management. Whenever a perioperative hypersensitivity reaction is suspected, close collaboration between anaesthetist and the allergy team investigating the patient is paramount, in order for the patient to be appropriately investigated and have an uneventful anaesthetic in the future.