Anaphylaxis is type 1 IgE mediated multisystem syndrome, caused by the release of multiple inflammatory mediators such as histamine, in response to a known or unknown allergen. The syndrome may vary from a mild reaction to life-threatening. Examples of allergens that may cause or anaphylaxis are:

  • Medicines (e.g. penicillin)
  • Latex
  • Bee stings
  • Peanuts, fish or other foods

Symptoms and signs:

These may develop over minutes:

  • Airway – lip, tongue, pharyngeal, epiglottis swelling/oedema, causing:
    • Airway occlusion
  • Breathing – wheeze may develop, in life-threatening cases the chest may be quiet or silent
  • Cardiovascular
    • Peripheral vasodilation and warm to touch
    • Increased capillary permeability
    • Tachycardia
    • Profound hypotension
  • Skin
    • Angio-oedema
    • Pruritis/itching
    • Urticarial rash
  • GI tract
    • Nausea, vomiting
    • Cramps, diarrhoea

Management of anaphylaxis:

Your approach is, as always: check its safe, AB(& O2)CDE

Prompt recognition and early IM adrenaline are the keys to successful treatment.

GET HELP early

Remember oxygen

Remove allergen if possible

  • Airway Protect early
  • Breathing
    • Nebulised salbutamol 5 mg if wheezy. Repeat if necessary – May require several administrations
  • Circulation
    • IM adrenaline 0.5 mls 1:1000 (500 mcg)
    • IV access and give fluids (may need to be aggressive with fluid resuscitation. Note: NICE guidelines regarding fluid resuscitation do not apply in medical cases)

Second line treatments:

    • IV hydrocortisone 200 mg
    • IV Chlorpheniramine (Piriton) 10 mg


IM adrenaline may need repeating more than once, if the condition does not respond or deteriorates again.

Transfer to the nearest Emergency Department immediately.

Symptoms may recur several hours after the original episode (‘biphasic’ reaction), and depending on the allergen, the risk may last 24-36 hours. A post-anaphylaxis care plan should include education, a written action plan, prescription and instruction to the patient to carry an ‘epipen’ and considering wearing a medical alert bracelet or chain.