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Urticaria - Background information
What is it?
- Urticaria is a superficial swelling of the skin (epidermis and mucous membranes) that results in a red, raised, itchy rash. It can be localised or generalised.
- The mechanism involves local vasodilation of capillaries, and activation of mast cells which release histamine, resulting in plasma leaking from small blood vessels into the skin.
- Urticaria is also known as hives, nettle rash, or weals.
- Angio-oedema is a deeper form of urticaria with swelling in the dermis and submucosal or subcutaneous tissues. For more information, see the CKS topic on Angio-oedema and anaphylaxis.
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