Last reviewed 06/2020


  • urticaria (also known as hives, nettle rash, or weals) is a vascular reaction of the skin (upper dermis and mucous membranes) marked by transient appearance of slightly elevated patches - wheals - which are red or pale swellings that are often attended by severe itching. Urticaria can be localised or generalised (1)
  • urticaria is also used to define a disease which presents with short-lived itchy weals, angio-oedema or both together (2)
    • urticaria may be caused by many different factors including certain foods, drugs, infection, and emotional stress
  • the British Association of Dermatologists has classified utricaria according to the clinical presentation:
    • ordinary urticaria
      • acute (up to 6 weeks of continuous activity)
      • chronic (6 weeks or more of continuous activity)
      • episodic (acute intermittent or recurrent activity)
    • physical urticarias - repeatedly induced by the same physical stimulant
      • mechanical - delayed pressure urticaria, symptomatic dermographism
      • thermal - cholinergic urticaria, cold contact urticaria
      • other - solar urticaria, aquagenic urticaria
    • angio-oedema without weals
      • idiopathic
      • drug induced
      • C1 esterase inhibitor deficiency
    • contact urticaria - contact with allergens or chemical
    • urticarial vasculitis - defined by vasculitis on skin biopsy
    • autoinflammatory syndromes
      • hereditary
      • acquired (2)
  • two or more types of urticaria can occur at the same time in a patient (1)
  • urticaria is frequently accompanied by angioedema (3)

Click here for images of urticarial rash