Allergic urticaria

Abstract

Urticaria, commonly known as hives, is characterized by the episodic appearance of pruritic, erythematous papules or plaques with superficial swelling of the dermis. Urticaria is classified as either acute or chronic based on symptom duration. Acute urticaria, which is defined as having hives for less than 6 weeks, is estimated to occur in 15-23 % of the population, although cases are likely to be underreported due to the short-lived nature of the disease. Chronic urticaria, defined by symptom duration of greater than 6 weeks, can be further classified as physical urticaria or chronic idiopathic urticaria (CIU). Physical urticarias are comprised of many subtypes in which a specific trigger can quickly induce hives, while the majority of hives in CIU do not occur as a result of a known trigger. The prevalence of physical urticaria is not well-established, but it is thought to account for 20-35 % of all cases of chronic urticaria. CIU, which has been renamed as chronic spontaneous urticaria (CSU) in recent guidelines, occurs in approximately 0.1-3 % of the population and, like many forms of chronic urticaria, has a female predominance.