Urtikaria

Urtikaria, commonly known as hives, is a skin condition characterized by transient, itchy wheals caused by edema in the superficial dermis from mast cell degranulation and the release of histamine and other mediators. Lesions are usually red or pale, vary in size, and appear and disappear over hours. In many cases, angioedema—swelling of deeper skin layers, especially around the eyes, lips, and hands—may accompany the wheals.

Urtikaria is classified as acute when it lasts less than six weeks and chronic when it persists for six weeks or longer. Acute urticaria is often linked to infections, medications, foods, or physical triggers, whereas chronic urticaria can be idiopathic or autoimmune. Physical urticarias include dermographism (triggered by scratching or rubbing), cold or heat exposure, pressure, solar exposure, vibratory stimuli, and cholinergic triggers.

Diagnosis is mainly clinical, based on history and examination. Tests are selective and may include complete blood counts, thyroid autoantibodies, and, in persistent cases, tests to exclude underlying autoimmune disease. Special challenge tests may be used to identify physical urticarias. Angioedema may require assessment for different mechanisms, including hereditary angioedema, if facial or airway involvement is present.

Management centers on symptom relief and trigger avoidance. Second-generation oral antihistamines are first-line, given at standard doses and, if needed, at higher doses. Short courses of systemic corticosteroids may be used for acute flares. In chronic, refractory cases, options include leukotriene receptor antagonists, H2 blockers, and the biologic agent omalizumab. Education on triggers, avoidance strategies, and regular follow-up are important for prognosis, as chronic urticaria can persist for months to years but often improves over time.