- Another name for the hives. Raised, itchy areas of skin that are usually a sign of an allergic reaction. Hives can be rounded or flat-topped but are always elevated above the surrounding skin. They reflect circumscribed dermal edema (local swelling of the skin). The hives are usually well circumscribed but may be coalescent and will blanch with pressure. The hives typically last less than 4 hours but they may stay for days or weeks. Approximately 20% of the population has experienced a bout of urticaria.
* * *An eruption of itching wheals, usually of systemic origin; it may be due to a state of hypersensitivity to foods or drugs, foci of infection, physical agents (heat, cold, light, friction), or psychic stimuli. SYN: hives (1), urtication (2). [L. urtica]- cholinergic u. a form of physical or nonallergic u. initiated by heat ( e.g., hot baths, physical exercise, pyrexia, exposure to sun or to a warm room) or by excitement; the rather distinctive lesions consist of pruritic areas 1–2 mm in diameter surrounded by bright red macules. SYN: heat u..- u. chronica SYN: chronic u..- cold u. wheal formation that develops after exposure to lowered temperatures, with or without demonstrable passive-transfer antibodies.- u. endemica, u. epidemica u. caused by the nettling hairs of certain caterpillars.- giant u. SYN: angioedema.- papular u. a sensitivity reaction to insect bites, especially human and pet fleas, seen mostly in young children as wheals followed by papules on exposed areas.- u. perstans a form of chronic u. in which the wheals persist unchanged for long periods; includes urticarial vasculitis.- u. pigmentosa cutaneous mastocytosis resulting from an excess of mast cells in the superficial dermis, producing a chronic eruption characterized by flat or slightly elevated brownish papules which urticate when stroked. The disease in children frequently involutes spontaneously whereas resolution is rare with adult onset and there may be systemic lesions. SEE ALSO: diffuse cutaneous mastocytosis.- solar u. a form of u. resulting from exposure to sunlight; some patients have passive-transfer antibodies and others do not.- u. vesiculosa SYN: u. bullosa.
* * *ur·ti·car·i·al -ē-əl adj
* * *n.an itchy rash resulting from the release of histamine by mast cell. Individual swellings (weals) appear rapidly and resolve spontaneously within hours. Acute urticaria is common and represents an immediate response to such allergens as seafood or strawberries. Chronic urticaria is not an allergic condition and may persist for years. Angio-oedema occurs when the weals involve the lips, eyes, or tongue, which may swell alarmingly and constitute a medical emergency. Urticaria can be prevented by taking antihistamines regularly. Cholinergic urticaria is a condition in which very small weals are brought on by heat, exercise, or emotion; treatment may be with hydroxyzine or ketotifen.
* * *ur·ti·ca·ria (ur″tĭ-karґe-ə) [Urtica + -ia] a vascular reaction in the upper dermis, usually transient, consisting of localized edema caused by dilatation and increased capillary permeability with wheals. Most types are named for the causative stimulus or mechanism, such as physical urticaria and contact urticaria. Angioedema is the same physiological response in the deep dermis or subcutaneous or submucosal tissues. Called also hives. urticarial, urticarious adj
Medical dictionary. 2011.