Clinical manifestations are due to hypotension (from vasodilation and loss of plasma volume), bronchospasm, laryngeal and/or pharyngeal oedema.
Type I hypersensitivity reaction (systemic allergic reaction in someone who has been previously sensitised; IgE mediated)
Penicillin is commonest cause – also occurs as reaction to narcotics, local anaesthetics, foods, bee stings
Early signs (within 1 – 15 minutes) – ‘uneasy’ feeling; ‘lump in throat’; hoarseness of voice; angioedema; stridor; wheezing; ‘flush’; urticaria; pruritis; nausea; vomiting
More serious signs – hypotension; hypoxia; cardiac arrhythmia; convulsions; circulatory collapse
Initial – epinephrine/adrenaline; antihistamine if detected early; oxygen; IV volume expander (eg saline); bronchodilator