Urticaria and angioedema
Urticaria, commonly known as hives, is an episodic, usually self-limited skin reaction characterized by local dermal wheals surrounded by an erythematous flare. Angioedema, which can present either subcutaneously or dermally, produces deeper, larger wheals (usually on the hands, feet, lips, genitals, and eyelids) and a more diffuse swelling of loose subcutaneous tissue. Urticaria and angioedema can occur simultaneously, but angioedema may last longer.
Causes
Urticaria and angioedema are common allergic reactions. Causes include allergy to drugs, foods, insect stings and, occasionally, inhalants, such as animal dander and cosmetics, that provoke an immunoglobulin (Ig) E-mediated response to protein allergens. However,
certain drugs may cause urticaria without an IgE response.
certain drugs may cause urticaria without an IgE response.
When urticaria and angioedema are part of an anaphylactic reaction, they almost always persist long after the systemic response has subsided. This occurs because circulation to the skin is inhibited after an allergic reaction, which results in slow histamine reabsorption at the reaction site. Nonallergic urticaria and angioedema are probably also related to histamine release.
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