Urticaria [Hives]
Urticaria [Hives]: Excerpt from Handbook of Signs & Symptoms (Third Edition)
Urticaria is a vascular skin reaction characterized by the eruption of transient pruritic wheals — smooth, slightly elevated patches with well-defined erythematous margins and pale centers of various shapes and sizes. It’s produced by the local release of histamine or other vasoactive substances as part of a hypersensitivity reaction. (See Recognizing common skin lesions, page 467.)
Acute urticaria evolves rapidly and usually has a detectable cause, commonly hypersensitivity to certain drugs, foods, insect bites, inhalants, or contactants; emotional stress; or environmental factors. Although individual lesions usually subside within 12 to 24 hours, new crops of lesions may erupt continuously, thus prolonging the attack.
Urticaria lasting longer than 6 weeks is classified as chronic. The lesions may recur for months or years, and the underlying cause is usually unknown. Occasionally, a diagnosis of psychogenic urticaria is made.
Angioedema, or giant urticaria, is characterized by the acute eruption of wheals involving the mucous membranes and, occasionally, the arms, legs, or genitals.
Emergency interventions
In an acute case of urticaria, quickly evaluate respiratory status, and take vital signs. Ensure patent I.V. access if you note any respiratory difficulty or signs of impending anaphylactic shock. Also, as appropriate, give local epinephrine or apply ice to the affected site to decrease absorption through vasoconstriction. Clear and maintain the airway, give oxygen as needed, and institute cardiac monitoring. Have resuscitation equipment at hand, and be prepared to begin cardiopulmonary resuscitation. Intubation or a tracheostomy may be required.
History
If the patient isn’t in distress, obtain a complete history. Does he have any known allergies? Does the urticaria follow a seasonal pattern? Do certain foods or drugs seem to aggravate it? Is there a relationship to physical exertion? Is the patient routinely exposed to chemicals on the job or at home? Has the patient recently changed or used new skin products or detergents? Obtain a detailed drug history, including prescription and over-the-counter drugs. Note any history of chronic or parasitic infection, skin disease, or a GI disorder.
Medical causes
Anaphylaxis
Anaphylaxis — an acute reaction — is marked by the rapid eruption of diffuse urticaria and angioedema, with wheals ranging from pinpoint to palm-size or larger. Lesions are usually pruritic and stinging; paresthesia commonly precedes their eruption. Other acute findings include profound anxiety; weakness; diaphoresis; sneezing; shortness of breath; profuse rhinorrhea; nasal congestion; dysphagia; and warm, moist skin.
Hereditary angioedema
With hereditary angioedema — an autosomal dominant disorder — cutaneous involvement is manifested by nonpitting, nonpruritic edema of an extremity or the face. Respiratory mucosal involvement can produce life-threatening acute laryngeal edema.
Lyme disease
Although not diagnostic of Lyme disease — a tick-borne disease — urticaria may result from the characteristic skin lesion (erythema chronicum migrans). Later effects include constant malaise and fatigue, intermittent headache, fever, chills, lymphadenopathy, neurologic and cardiac abnormalities, and arthritis.
Other causes
Drugs
Drugs that can produce urticaria include aspirin, codeine, dextrans, immune serums, insulin, morphine, penicillin, quinine, sulfonamides, and vaccines.
Radiographic contrast medium
Radiographic contrast medium, especially when administered I.V., commonly produces urticaria.
Special considerations
To help relieve the patient’s discomfort, apply a bland skin emollient or one containing menthol and phenol. Expect to give an antihistamine, a systemic corticosteroid or, if stress is a suspected contributing factor, a tranquilizer. Tepid baths and cool compresses may also enhance vasoconstriction and decrease pruritus.
Teach the patient to avoid the causative stimulus, if identified.
Pediatric pointers
Pediatric forms of urticaria include acute papular urticaria (usually after insect bites) and urticaria pigmentosa (rare). Hereditary angioedema may be causative.
Book Source Details
- Book Title: Handbook of Signs & Symptoms (Third Edition)
- Author(s): Springhouse
- Year of Publication: 2006
- Copyright Details: Handbook of Signs & Symptoms (Third Edition), Copyright © 2006 Lippincott Williams & Wilkins.
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- "Professional Guide to Diseases (Eighth Edition)" (2005)
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- "The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter" (2000)
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- "Alarming Signs and Symptoms: Lippincott Manual of Nursing Practice Series" (2007)
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
» Next page: Urticaria (A Pocket Manual of Differential Diagnosis)
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