Wheals

Urticaria

• 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 urticaria 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 (1)

Click here for images of urticarial rash

Reference:

• 1. Urticaria and angioedema - an overview. Primary Care Dermatology Society. May 2022.
• 2. Sabroe RA et al. British Association of Dermatologists guidelines for the management of people with chronic urticaria 2021. British Journal of Dermatology. November 2021. Vol. 186 Issue 3.