hives

Hives, or urticaria, is a skin condition characterized by transient, itchy welts that can appear anywhere on the body. Individual wheals are raised, well defined, and vary in size. They may merge into larger lesions and typically move or fade within hours. Hives may be accompanied by angioedema, swelling beneath the skin around the lips, eyes, or throat, which can be serious if it affects breathing.

Urticaria is classified as acute when it lasts less than six weeks and chronic when it persists beyond six weeks. Acute urticaria is commonly triggered by infections, foods, medications (such as antibiotics or NSAIDs), insect stings, or physical factors. Chronic urticaria is often idiopathic, though autoimmune mechanisms are suspected. Physical urticarias include responses to pressure, cold, heat, sunlight, or vibration.

Pathophysiology involves mast cell activation in the skin with release of histamine and other mediators, causing vascular leakage and edema in the superficial dermis, which leads to itching and welts.

Diagnosis and treatment are largely clinical and based on history and examination. Laboratory tests are not routinely required but may be considered if urticaria is chronic or accompanied by concerning features. Management centers on avoiding triggers and relieving symptoms with non-sedating second-generation antihistamines (examples include cetirizine, loratadine, and fexofenadine). If symptoms persist, doses can be increased up to fourfold. Short courses of oral corticosteroids may be used for severe flares. For chronic refractory cases, options include leukotriene receptor antagonists or anti-IgE therapy such as omalizumab. Epinephrine should be available for signs of anaphylaxis.

Most cases resolve within weeks to months. A substantial minority develop chronic urticaria with recurrent flares, but many achieve long-term remission with appropriate treatment. Recurrence is common, and management focuses on symptom control and trigger avoidance.