Urticaria & angioedema

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  • Urticaria – [Never lasts > 24h – consider dermatology review] [2 types – acute and chronic]
    • Acute
      • Commonly viral, drug – esp. NSAIDs
      • May be food allergy if clear history
      • Non-recurring, highly unlikely to be allergy
    • Chronic [>6w] [Majority can be managed in primary care]
      • Common triggers – Viral, physical – pressure, temperature; stress, additive, colourants – [cause not usually identified ?autoimmune]
      • [Tests unlikely to be beneficial] [If patients want referral do Total IgE & IgE for nut and food mix]
      • Usually burns out by 2y
      • Treatment
        • Avoid trigger & NSAID [consider aspirin to clopidogrel]
        • Regular non-sedating antihistamine – higher dose may help – [Cetirizine] [Fexofenadine] [Loratidine]
        • Add sedating antihistamine – [Chlorpheniramine] [Hydroxyzine]
  • Angioedema without urticaria
    • Usually due to NSAID or ACEi
      • ACEi effect can last several weeks after stopped – if recurrs >6w after stopped, consider another cause
    • Hereditary or acquired angioedema [impaired function of C1 inhibitor]
      • Before referral – Complement C4 bloods, myeloma screen & C1 esterase inhibitor concentration
  • Referral to allergy clinic
    • [Life threatening symptoms e.g. laryngeal spasms] [atypical urticarial lesions – e.g. urticarial vasculitis] [severe anaphylactoid-type reactions] [suspected hereditary or acquired angioedema] [Oedema <40y]
    • No response to NSAID & ACEi avoidance for 6w
    • Response failure to 2 regular different antihistamine combinations each for 6-8w

Allergic food reactions

  • Presentation
    • Symptoms – [within 2h] [almost always urticaria & angioedema] [often GI/Resp. disturbance] [adult onset is rare]
    • Usually eggs, milk, peanuts & other nuts, soya, fish & seafood
    • Initial investigation – IgE specific bloods [high -ve predictive value]
    • Not food intolerance [e.g. bloated, diarrhoea] [Poorly understood] [do not refer to allergy specialist]
  • Referral to allergy clinic
    • True food allergy suspected
      • First take Total & specific IgE first for common food mix & nut mix & others as implicated

Links

Patient.co.uk on urticaria