Aetiology

• Although it is uncommon, most commonly encountered precipitants include food, drugs and venom (1)
  • vaccines
  • drugs:
    • antibiotics
    • heparin
    • neuromuscular blocking agents
    • iron injections
    • anti-inflammatory analgesics
    • contrast media
  • hyposensitising agents
  • insect bites and stings- wasp, bee
  • blood products
  • certain foods, for example peanuts, almonds,walnut, fish,milk
• the relative significance of these factors varies with the age, in that(1):
  • food is particularly significant in children
  • drugs being a much more common cause in the elderly.
• it is more likely to occur after parenteral injections. The reaction is likely to be more severe if the patient is re-exposed.
• although atopic patients are more susceptible, why some individuals should react so markedly to this repeat exposure to an antigen is not understood.

Reference:

• (1) Emergency treatment of anaphylactic reactions.Guidelines for healthcare providers.Working Group of the Resuscitation Council (UK).2008