welts

Welts, also known as wheals or urticarial plaques, are raised, red or pale edematous areas of skin that are often accompanied by itching. They vary in size and shape and may appear singly or in clusters. Welts typically develop rapidly after exposure to a trigger and fade within hours, though new welts can appear as others disappear.

Common triggers include allergic reactions to foods, medicines, or insect bites; physical factors such as pressure, cold, heat, sun exposure, or friction; contact with irritants; and, less commonly, infections or autoimmune conditions. In some cases, the cause cannot be identified (idiopathic urticaria).

Pathophysiology involves local swelling in the superficial skin layers due to dilation and leakage from blood vessels, mediated by histamine release from mast cells. This leads to the characteristic itchy, raised lesions. Hives are a common form of welts and may occur as part of an allergic reaction or chronic urticaria.

Diagnosis is typically clinical, based on history and examination. In persistent or recurrent cases, or when anaphylaxis risk is suspected, further evaluation or allergy testing may be pursued. Warning signs requiring urgent care include difficulty breathing, swelling of the lips or tongue, or widespread swelling with fainting.

Treatment focuses on removing triggers when possible and relieving symptoms. Non-prescription antihistamines are commonly used; topical corticosteroids can reduce itching and inflammation. Severe or prolonged episodes may require a short course of systemic corticosteroids or other therapies under medical guidance.

Prognosis varies; most welts resolve within hours to days, though some forms of chronic urticaria can persist for weeks to months. Prevention centers on trigger avoidance and skin care.