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Reversible optic neuropathy secondary to metronidazole
  1. Natalie Anwyll,
  2. Paul Gerry and
  3. Joe Gormley
  1. Neurology, Royal Devon and Exeter NHS Foundation Trust, Exeter, UK
  1. Correspondence to Dr Natalie Anwyll; natalieanwyll{at}


Metronidazole is a nitroimidazole antibiotic used in treating anaerobic bacteria and protozoal infections. It was first licensed for the treatment of Trichomonas vaginalis but is now used in the management of various gastrointestinal and genitourinary infections. Many neurological side effects are well documented, although there is scarce literature illustrating optic neuropathy secondary to metronidazole. We describe a case report of a 36-year-old man who presented with symptomatically reduced central visual loss on a background of a 2-year history of metronidazole use for a perianal fistula. Electrophysiology demonstrated bilateral optic neuropathy, with pattern visual evoked potential traces demonstrating marked latency and small amplitude responses of the P100 waves, which improved to within normal limits on cessation of metronidazole. This case study demonstrates clinical and electrophysiological reversibility of optic neuropathy secondary to high dose and prolonged metronidazole use.

  • drugs and medicines
  • drugs: CNS (not psychiatric)
  • neuroopthalmology

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  • Contributors JG is the neurologist who first met the patient in clinic and diagnosed him as optic neuropathy secondary to metronidazole. PG is a technician in neurophysiology who performed the visual evoked potentials and multifocal electroretinography of the patient. NA is a foundation doctor who has been in contact with the patient following the resolution of his symptoms and has formulated the case report.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.