Metronidazole: Indications & Dosage

Metronidazole

Generic Name

Metronidazole

Group

Nitroimidazole

Mechanism of Action

Under anaerobic conditions, it is reduced to toxic metabolites that disrupt bacterial DNA and inhibit nucleic acid synthesis, leading to cell death. Active mainly against anaerobic bacteria and protozoa.

Indications

Anaerobic bacterial infections (e.g., Bacteroides fragilis)
Clostridioides difficile infection
Trichomoniasis
Amebiasis (Entamoeba histolytica)
Giardiasis
Pelvic inflammatory disease (as part of combination therapy)
Dental and intra-abdominal infections

Dose

Adults: 500–750 mg orally or IV every 8–12 hours
Children: 30 mg/kg/day divided every 8 hours
Adjust dose in severe hepatic impairment

Major Side Effects

Gastrointestinal upset (nausea, vomiting, metallic taste)
Neurological effects: headache, dizziness, peripheral neuropathy (long-term use)
Rash
Rare: seizures or encephalopathy
Disulfiram-like reaction with alcohol

Contraindications

Hypersensitivity to metronidazole or other nitroimidazoles
First trimester of pregnancy (use only if benefits outweigh risks)
Alcohol use during therapy

Compatible Fluid

0.9% Sodium chloride (normal saline)
5% Dextrose (D5W)

Route of Administration

Oral or Intravenous (IV)

Type of Administration

Tablet, Suspension, or Parenteral injection (IV)

Antibiotic Reference

Metronidazole

Generic Name

Group

Mechanism of Action

Indications

Dose

Major Side Effects

Contraindications

Compatible Fluid

Route of Administration

Type of Administration