Superficial swelling of the skin that results in a red, raised, itchy rash.  It can be localised or generalised.




  • Release of a variety of inflammatory mediators (including histamine, bradykinin, leukotrienes, prostaglandins) cause close-by vessels to become leaky.  Leakage of plasma causes the classic oedema/wheal whilst histamine causes an itch.
  • Can either be immune mediated on ‘non-immune’ urticaria
    • Immune-mediated urticaria
      • Can be associated with a type I (immediate allergic IgE-mast cell response e.g. to latex, cosmetics); type II (cytotoxic T cell mediated causing an urticarial vasculitis (e.g. hereditary angioedema) and type III (immune-complex diseases e.g. SLE that can cause urticaria).
    • Non-immune mediated
      • Normally complement mediated in viral/bacterial infections but can also be due to transfusion reactions (technically IgE mediated), opioids and other drugs, physical stimulation etc
    • Note Idiopathic urticaria and chronic urticaria
      • Some patients exhibit chronic urticaria for which there is no known cause/pathogenesis.  About a 1/3 of chronic cases are thought to be immune mediated.


English: Uriticaria
English: Uriticaria (Photo credit: Wikipedia)


  • Classic urticarial weals (small, raised areas 1-2cm that develop suddenly and usually last <24 hours, but may reappear again within hours) with itch
    • Acute <6weeks vs Chronic >6weeks
    • It is important to ask about:
      • the possibility of food allergy (new food/prev allergy)
      • drug history (particularly NSAIDs/aspirin, OTC medications, supplements, penicillins, ACE inhibitors) as there may be an allergy.  Note also any PMHx.
      • Any recent viral/bacterial infections (acute or chronic)?
      • Where the hives caused by physical stimuli (hot/cold/pressure etc)?
      • Any bites/insect manifestations?
      • Also take an extensive occupational/hobbies history.


  • You might (based on the history) want to do FBC/U&E/LFTs and or blood cultures if you suspect a more systemic cause (e.g. urticarial vasculitis where urticaria is painful and persistent).
  • You might also want to do RAST if there is a specific allergen that you think could be causing the urticaria.


  • Where possible, avoid the trigger
  • For severe acute urticaria, consider using a short course of prednisolone (40mg/day 3-5 days) in addition to a non-sedating anti-histamine e.g. (cetirizine, fexofenadine, loratidine)
  • Antihistamines are the main treatment otherwise (other than treatment of the underlying cause)
    • sedating anti-histamines may be useful for patients who have problems with nocturnal itching (not uncommon)
    • cooling agents e.g. menthol/calamine may also be of benefit
  • consider referral to a specialist if symptoms persist >6 weeks and are not responding to treatments

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