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Hypersensitivity reactions to metronidazole

Isabel García-Rubio1, Consuelo Martínez-Cócera, Sara Santos Magadán

  • 1Allergy Department, Hospital Clínico San Carlos, Madrid Spain. igrubio@hotmail.com

Allergologia Et Immunopathologia
|April 12, 2006
PubMed
Abstract

Insights

Hypersensitivity reactions to metronidazole are increasingly reported. Oral provocation is the gold standard for diagnosing metronidazole hypersensitivity, as skin tests show low sensitivity in identifying these reactions.

Area of Science:

  • Clinical Immunology
  • Pharmacovigilance
  • Dermatology

Background:

  • Hypersensitivity reactions to metronidazole are rarely documented but appear to be increasing.
  • Growing use of metronidazole for amebiasis and anaerobic infections contributes to this trend.
  • This study investigates the diagnostic utility of oral provocation for suspected metronidazole hypersensitivity.

Purpose of the Study:

  • To evaluate the effectiveness of oral provocation in diagnosing metronidazole hypersensitivity.
  • To compare oral provocation with cutaneous testing methods.
  • To assess the incidence and presentation of metronidazole-induced cutaneous reactions.

Main Methods:

  • Four patients with suspected metronidazole hypersensitivity underwent prick tests with metronidazole and spiramycin, and epicutaneous tests with metronidazole.
  • Controlled oral challenges with placebo, erythromycin, spiramycin, and metronidazole were performed.
  • One patient was excluded from oral metronidazole challenge due to a positive prick test.

Main Results:

  • Only one patient had a positive metronidazole prick test; epicutaneous tests were negative.
  • All patients tolerated erythromycin and spiramycin.
  • Oral provocation confirmed metronidazole hypersensitivity in three patients, presenting as delayed exanthema or early erythema and itching.

Conclusions:

  • Metronidazole can cause immune-mediated cutaneous reactions, including early and delayed presentations.
  • Cutaneous tests (prick and epicutaneous) demonstrate low sensitivity for diagnosing metronidazole hypersensitivity.
  • Oral provocation is the gold standard for diagnosing metronidazole hypersensitivity when skin tests are inconclusive.

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