Urticaria

Abstract

Urticaria is a common illness characterised by itchy weals, angioedema or both. It may be acute (lasting less than 6 weeks) or chronic (lasting 6 weeks or more). Weals and angioedema are characterised by their transient nature and resolve within hours or days without damage. Most acute urticaria is spontaneous and most inducible urticarias are chronic. Several subtypes of inducible urticaria are defined by the provoking stimulus but overlaps between them and spontaneous types occur. The mast cell is central to all types of urticaria and histamine is a major mediator. Allergy may be a cause of acute urticaria but probably never chronic urticaria. Autoimmune and autoallergic aetiologies have been recognised in chronic spontaneous urticaria but the cause remains elusive in many patients and may be multifactorial. Management hinges on identifying a cause or trigger if one can be found, addressing co‐morbidities and optimising pharmacological treatments with antihistamines, omalizumab and other low‐evidence‐based treatments when appropriate to control symptoms. Natural remission can be expected but the illness may be prolonged in some patients.