Urticaria, or hives, (sometimes referred to as welts or wheals) are a common disorder, with a prevalence of approximately 20 percent in the general population . A typical urticarial lesion is an intensely pruritic, erythematous plaque (picture 1). Urticaria is sometimes accompanied by angioedema, which is swelling deeper in the skin. A presumptive trigger, such as a drug, food ingestion, insect sting, or infection, may be identifiable in patients with new onset urticaria, although no specific cause is found in many cases, particularly when the condition persists for weeks or months. (See 'Etiologies' below.)
The epidemiology, clinical manifestations, etiologies, diagnosis, and management of new onset urticaria will be reviewed here. Chronic urticaria and isolated angioedema are discussed separately. (See "Chronic urticaria: Clinical manifestations, diagnosis, pathogenesis, and natural history" and "Chronic urticaria: Standard management and patient education" and "An overview of angioedema: Clinical features, diagnosis, and management".)
CATEGORIZATION OF URTICARIA
Urticaria (with or without angioedema) is commonly categorized by its chronicity:
Acute urticaria — Urticaria is considered acute when it has been present for less than six weeks.
Chronic urticaria — Urticaria is considered chronic when it is recurrent, with signs and symptoms recurring most days of the week, for six weeks or longer.