Introduction

Life-threatening type I hypersensitivity reaction, triggered by exposure to a wide range of antigens and involving multiple organ systems

• Mortality rate: 10%

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Aetiology

• Foods (eg, milk, soy, eggs, nuts, and shellfish)

• Medications (eg, antibiotics [penicillin], nonsteroidal anti-inflammatory drugs, anaesthetics)

• Venom (Hymenoptera stings)

• IV contrast materials

• Latex

• Idiopathic (20%)

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Pathophysiology

Result of IgE–mediated mast cell degranulation, which releases inflammatory immune mediators causing vasodilation and vascular leakage resulting from enhanced permeability of the postcapillary venules in the vascular beds of visceral organs, skin, and mucous membranes.

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Clinical features

Classic presentation:

• Urticaria or angioedema
• Hypotension
• Bronchospasm

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Management