Chronic urticaria (CU) is defined by the presence of urticaria (hives) on most days of the week for a duration of longer than six weeks. The prevalence of this disorder is up to 1 percent of the general population in the United States and is believed similar around the world . Associated angioedema occurs in about 40 percent of patients with CU and usually affects the lips, cheeks, periorbital areas of the face, extremities, and genitals .
The management of CU in most patients as well as counseling of individuals with this disorder will be discussed here. Treatment of CU that is refractory to standard management and the diagnosis, pathogenesis, and prognosis of CU are presented separately. (See "Chronic urticaria: Treatment of refractory symptoms" and "Chronic urticaria: Clinical manifestations, diagnosis, pathogenesis, and natural history".)
Disorders involving isolated angioedema, urticarial vasculitis, and specific physical forms of CU (such as delayed-pressure urticaria, cholinergic urticaria, or cold urticaria) are discussed separately. (See "An overview of angioedema: Pathogenesis and causes" and "Urticarial vasculitis" and "Physical urticarias" and "Cold urticaria".)
Terminology — In this review, the term CU refers to patients with isolated chronic idiopathic urticaria (CIU), as well as those with both urticaria and angioedema.
Chronic urticaria and chronic idiopathic urticaria — The terms "chronic urticaria" and "chronic idiopathic urticaria" are used interchangeably in this review and in the medical literature. These terms refer to CU in which appearance of lesions is not triggered by consistent or identifiable factors. However, physical urticaria syndromes are variably included in CU. Physical urticarias are disorders in which urticaria is induced by one or more environmental stimuli, such as heat, cold, pressure applied to the skin, exercise, water, vibration, and sunlight. The inclusion of physical urticaria in the definition of CU is based upon the observation that some patients with CU have symptoms triggered by a physical stimulus on some occasions, while most of the symptoms are spontaneous.