See also:

Anaphylaxis is defined as an acute life-threatening allergic reaction.  It is usually – but not exclusively – mediated by IgE-antibodies. Criteria from EAACI given below. Anaphylactoid reactions are immediate systemic reactions that mimic anaphylaxis but for which an IgE-mediated immune mechanism can not be established – most people don’t bother trying to make a distinction now.

Resuscitation Council definition (2021):

  • Sudden onset, rapid progression
  • Airway/breathing/circulation problems (not specified)
  • “Life threatening” includes:
    • hoarse voice, stridor
    • wheeze, work of breathing, cyanosis, fatigue
    • Signs of shock (presumably pale, clammy), low BP, confusion, reduced consciousness
    • (not tongue swelling or persistent cough)


Where no cause identified consider:

Rare allergens, eg galactose alpha-1,3 galactose , pigeon tick bite (Argax reflexus), wheat-dependent exercise-induced anaphylaxis, Anisakis simplex allergy.

Differential includes mast cell disorders, asthma, panic attacks, conversion disorder, globus hystericus, vocal cord dysfunction, scombroid poisoning, vasoactive amine intolerance, carcinoid syndrome and phaeochromocytoma. 

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