Morbilliform and urticarial drug eruptions

Published on 11/06/2015 by admin

Filed under Pediatrics

Last modified 22/04/2025

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Morbilliform drug eruption due to trimethoprim-sulfamethoxazole.

Morbilliform drug eruption due to trimethoprim-sulfamethoxazole.

Urticarial drug eruption with partially clearing areas due to ceclor.

Urticarial drug eruption due to phenobarbital or trimethoprim.

CLINICAL FEATURES

Widespread itchy red macules following ingestion of a drug constitute a morbilliform drug reaction. The rash becomes confluent in areas with clearing of adjacent areas of skin. The eruption lasts 7 to 14 days and may be associated with malaise and arthralgias. The most likely responsible drugs are non-steroidal anti-inflammatory drugs, penicillins, cephalosporins and sulfonamide antibiotics (including trimethoprim-sulfamethoxazole combinations), anticonvulsants and oral fluconazole or ketoconazole antifungal drugs. Morbilliform drug eruptions often mimic viral exanthems.

Urticarial drug eruptions are characterized by hives that move from skin site to skin site within hours, with new areas of involvement appearing almost continuously. Giant hives with clear centers may be seen.

Angioedema is rarely seen but can be accompanied by fever and arthralgias. Cephalosporins are most responsible for the angioedema-type reaction. The same drugs responsible for morbilliform reactions also are implicated in urticarial drug reactions, with ibuprofen and ceclor the most common. The urticarial response usually lasts 7 to 14 days but occasionally lasts 4 to 6 weeks.

TREATMENT

Removal of the suspected offending drug is necessary.

In a child on multiple medications eliminating the most often associated may result in stopping more than one medication, and sorting out the responsible medication can be difficult. Oral antihistamines may help suppress the urticarial eruptions and those with angioedema may require 1 : 1000 aqueous epinephrine administered subcutaneously 0.2 to 0.5 mL, followed by oral antihistamines, and, if severe, the addition of oral steroids until the edema subsides.

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