C. diff Risk


Oral Bioavailability


Approximate Cost



500 mg PO/IV q8h

CrCl ≥10 mL/min

  • 500 mg IV/PO Q8h

CrCl <10 mL/min (ESRD not on HD)

  • 500 mg IV/PO Q12h

Dialysis (HD or CRRT)

  • 500 mg IV/PO Q8h

Metronidazole has high oral bioavailability – consider initiating with/switching to oral therapy when patient tolerating orals

Consider dose reduction with severe hepatic impairment (Child-Pugh C)

Creatinine Clearance >50mL/min/1.73m²Creatinine Clearance 10-50mL/min/1.73m²Creatinine Clearance ≤10mL/min/1.73m²10mg/kg/dose q8HNo change10mg/kg/dose Q12H

500mg Q8H

General Information

Adverse Effects

  • Nausea

  • Diarrhea

  • Disulfiram-like reactions with alcohol

  • Metallic taste

  • Reversible neutropenia

Drug Monitoring

Consider baseline LFTs


  • GI effects

  • Avoid alcohol

  • With prolonged therapy (>6wks) or if symptoms develop assess for peripheral/optic neuropathy

Major Interactions

Ethanol- disulfiram-like reaction

Increases levels of cyclosporine, lithium, warfarin, and phenobarbital and phenytoin

Additional Information

Bacterial, protozoal and ameobic DNA is fragmented by reactive nitroso-imidazole radicals


Antimicrobial class: Nitroimidazole

Pregnancy category: B

Average serum half life: 10 hours

Biliary penetration: Therapeutic

CSF penetration: Therapeutic

Lung penetration: Therapeutic

Urine penetration: Poor

Common Usage

Suspected or confirmed anaerobic infections including intra-abdominal, biliary, central nervous system, Clostridium difficile, Giardia, bacterial vaginosis, and pelvic infections.