Urticaria is characterised by transient wheals that consist of a swollen palpable centre often surrounded by an erythematous flare, associated with itching or, less commonly, a burning sensation. Individual wheals usually disappear within 1 to 24 hours leaving normal skin. The prognosis for eventual recovery from spontaneous and inducible urticaria is excellent. However, the time course is unpredictable and may extend to years, often following a relapsing and remitting course.