Core Dermatology Diagnoses / CategoriesInflammatory

Morbilliform drug eruption

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Publish date: Posted on
Last updated: October 21, 2023

Keywords #

morbilliform
morbilliform drug eruption
maculopapular drug eruption
exanthematous drug eruption
drug rash

Diagnosis #

Exanthematous drug eruption, also known as a morbilliform or maculopapular drug eruption, is the most common type of drug hypersensitivity reaction [1]. Diagnosis of exanthematous drug eruption should be suspected in a patient receiving drug treatment who presents with a new onset rash. This is thought to be delayed-type, T cell-mediated immune reaction[2]. These reactions may occur with a large variety of drugs. In most patients, the rash develops 5 to 14 days after starting treatment but may occur within one or two days in previously sensitized patients. Resolution occurs generally within 5 to 14 days after drug withdrawal [3]. Exanthematous drug eruptions are characterized by erythematous macules and papules coalescing into patches and plaques without secondary change that predominantly involve the trunk and proximal extremities[4]. In severe forms, the mucosae may be involved.

Key Concepts #
  • Exanthematous (morbilliform) drug eruptions are the most common type of adverse drug reaction.
  • Thought to be delayed-type, T cell-mediated immune reaction.
  • Characterized by erythematous macules and papules coalescing into patches and plaques without secondary change that predominantly involve the trunk and proximal extremities.
  • Rash develops 5 to 14 days after starting treatment but may occur within one or two days in previously sensitized patients.
Epidemiology #

Drug rashes occur in approximately 2% of individuals exposed to drugs [5]. Morbilliform drug eruption accounts for approximately 95 percent of cutaneous drug reactions. The highest rates of morbilliform drug eruption reported is for antibiotics (1-8%) [5].

Clinical Features #
  • Lesion morphology and distribution pattern closely resemble those of viral exanthems.
  • Eruption typically develops 5 to 14 days after treatment initiation but may occur within one or two days in previously sensitized individuals.
  • Erythematous macules and papules coalescing into patches and plaques without secondary change that predominantly involve the trunk and proximal extremities.
  • In mild forms, acral sites are most often spared, although the face, palms, and soles may be involved in more severe cases.
  • Systemic symptoms may include pruritus, low-grade fever, elevation of acute-phase proteins, and mild eosinophilia.
Differential Diagnoses #
Diagnostic Workup #

Diagnosis should be suspected in a patient receiving drug treatment who presents with new onset rash. Diagnostic evaluation is primarily clinical, and should include a detailed history, including drug use, infectious disease exposure, and symptoms of manifestations. Skin biopsy can confirm diagnosis, but is not always warranted in clear-cut cases.

Treatment #

Prompt withdrawal of the offending drug(s) is the most important step in management. The treatment of exanthematous drug eruptions is largely symptomatic (e.g. topical corticosteroids and oral antihistamines for associated pruritus). Eruption typically resolves in 5 to 14 days after drug withdrawal.

Slide Viewer #
https://utahderm.med.utah.edu/image-viewer/
References #
  1. Bircher, Andreas J., and Kathrin Scherer. “Delayed Cutaneous Manifestations of Drug Hypersensitivity.” The Medical Clinics of North America, vol. 94, no. 4, July 2010, pp. 711–25, x. PubMed, doi:10.1016/j.mcna.2010.04.001.
  2. Adam, Jacqueline, et al. “Delayed Drug Hypersensitivity: Models of T-Cell Stimulation.” British Journal of Clinical Pharmacology, vol. 71, no. 5, May 2011, pp. 701–07. PubMed, doi:10.1111/j.1365-2125.2010.03764.x.
  3. Lerch, Marianne, and Werner J. Pichler. “The Immunological and Clinical Spectrum of Delayed Drug-Induced Exanthems.” Current Opinion in Allergy and Clinical Immunology, vol. 4, no. 5, Oct. 2004, pp. 411–19. PubMed, doi:10.1097/00130832-200410000-00013.
  4. Absmaier, M., et al. “[Triggers of exanthematous drug eruptions: Stop intake, treat through or desensitization?].” Der Hautarzt; Zeitschrift Fur Dermatologie, Venerologie, Und Verwandte Gebiete, vol. 68, no. 1, Jan. 2017, pp. 29–35. PubMed, doi:10.1007/s00105-016-3907-y.
  5. Hoetzenecker, W., et al. “Adverse Cutaneous Drug Eruptions: Current Understanding.” Seminars in Immunopathology, vol. 38, no. 1, Jan. 2016, pp. 75–86. PubMed, doi:10.1007/s00281-015-0540-2.
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