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Biphasic anaphylaxis — SCE Acute Medicine MCQ

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ModerateOtherBiphasic anaphylaxisSCE Acute Medicine

A 45-year-old woman with asthma is admitted with pneumonia and receives IV co-amoxiclav. Ten minutes later she develops wheeze, hypotension and widespread urticaria. After IM adrenaline and fluids she improves, but symptoms recur 20 minutes later. What is the most appropriate next step in management?

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Correct answer: D — Repeat intramuscular adrenaline and continue observation for biphasic reaction risk

Recurrent airway or circulatory features after initial improvement represent ongoing anaphylaxis and require repeat IM adrenaline. Antihistamines are adjuncts for skin symptoms, not definitive treatment for recurrent anaphylaxis. Restarting the trigger is unsafe, and observation is needed because biphasic reactions can occur.

Reference: Resuscitation Council UK Anaphylaxis Guidance