Pediatric Dermatology Consult - January 2016

Treatment

The first step in managing urticaria multiforme is discontinuing any unnecessary antibiotic that could be triggering the hypersensitivity reaction. Urticaria multiforme typically resolves within 2 weeks without any treatment and responds to treatment with antihistamines within 24-28 hours.⁵ Treatment with a histamine₁ (H₁) blocker such as hydroxyzine, cetirizine, or diphenhydramine may be sufficient to resolve the eruption, but combination therapy with both an H₁ blocker and an H₂ blocker such as ranitidine can be helpful.4 Treatment with systemic corticosteroids usually is not necessary and should be reserved for severely symptomatic or refractory cases.^4,9

One of the reasons that it is important to distinguish urticaria multiforme from EM is to avoid overtreatment with systemic steroids,³ which are rarely required for urticaria multiforme but are sometimes useful, although controversial, for EM.¹ Additionally, the correct diagnosis is important for providing anticipatory guidance.⁶ Patients diagnosed with serum sickness–like reactions should be counseled to avoid unnecessary exposure to the culprit antibiotic in the future. Patients with urticaria multiforme who were taking an antibiotic at the onset of the eruption may consider avoiding the potential culprit antibiotic in the future, but it is important to keep in mind that urticaria multiforme is more strongly associated with antecedent infection than with antibiotic use, and so antibiotic avoidance may not be necessary unless justified by formal allergy testing. EM minor is more commonly associated with a herpes simplex virus infection than a drug reaction, so antibiotic use is less concerning, but patients should be counseled that recurrence is common and prophylactic treatment with acyclovir may be advised for recurrent disease.¹

References

1. “Neonatal and Infant Dermatology” (Elsevier Health Sciences: New York, 2014, pp. 456-70).
2. CRIAI. 2006;30(1):003-012.
3. Pediatr Dermatol. 1997;14(3):231-4.
4. Pediatrics. 2007;119(5):e1177-83.
5. Pediatr Dermatol. 2011;28(4):436-8.
6. The Journal of Allergy and Clinical Immunology in Practice. 2013;1(5):520-1.
7. Arch Dermatol. 1993;129(1):92-6.
8. “The Hypersensitivity Syndromes” in Hurwitz Clinical Pediatric Dermatology. 4 ed. Elsevier: New York, 2011, pp. 455-84.
9. J Clin Aesthet Dermatol. 2013;6(3):34-9.

Ms. Haddock is a medical student at University of California, San Diego School of Medicine and a research associate at Rady Children’s Hospital, San Diego. Dr. Eichenfield is chief of pediatric and adolescent dermatology at Rady Children’s Hospital-San Diego and professor of medicine and pediatrics at UC San Diego School of Medicine. Dr. Eichenfield and Ms. Haddock said they have no relevant financial disclosures. Email pdnews@frontlinemedcom.com.