Métronidazole Arrow (Metronidazole)

Metronidazole is employed to manage infections where anaerobic organisms or protozoa are involved.

• Bacterial vaginosis: eliminates anaerobic bacteria to restore normal vaginal flora.
• Trichomoniasis: eradicates Trichomonas vaginalis, relieving symptoms and preventing recurrence.
• Amoebiasis: destroys Entamoeba histolytica trophozoites in intestinal and extra‑intestinal disease.
• Clostridioides difficile infection: reduces toxin‑producing bacteria in the colon.
• Anaerobic bacterial infections: targets a broad range of anaerobes in soft‑tissue and intra‑abdominal sites.

• Metronidazole enters susceptible anaerobic cells and is reduced by microbial ferredoxin proteins to reactive nitro radicals. These radicals damage DNA, inhibit nucleic acid synthesis, and disrupt essential metabolic pathways, leading to irreversible cell injury and death of the pathogen.

Metronidazole may cause a range of adverse reactions, most of which are mild and reversible.

Common Side Effects

• Nausea: mild to moderate stomach upset.
• Metallic taste: transient metallic sensation in the mouth.
• Diarrhea: loose stools that usually resolve after therapy.
• Headache: mild headache during treatment.
• Skin rash: mild erythematous rash.

Serious or Rare Side Effects

• Severe allergic reaction: anaphylaxis with swelling, breathing difficulty.
• Peripheral neuropathy: tingling or numbness in extremities.
• Seizures: rare central nervous system events.
• Hepatotoxicity: elevated liver enzymes or jaundice.
• Stevens‑Johnson syndrome: severe skin blistering and mucosal involvement.

Before prescribing Metronidazole, clinicians should consider several safety measures.

• Assess liver function: monitor hepatic enzymes in patients with liver disease.
• Avoid alcohol: patients must abstain from alcohol to prevent disulfiram‑like reactions.
• Monitor renal function: dose adjustment may be needed in severe renal impairment.
• Watch for hypersensitivity: discontinue if rash or anaphylaxis occurs.
• Use caution in pregnancy: evaluate risk‑benefit ratio as safety data are limited.
• Store at room temperature: keep in original container, protect from moisture and direct sunlight.

Metronidazole can interact with several medicines, altering efficacy or safety.

Major Interactions (Avoid)

• Alcohol: may cause severe flushing, tachycardia, and hypotension.
• Warfarin: can increase anticoagulant effect, raising bleeding risk.
• Lithium: may raise lithium concentrations, leading to toxicity.

Moderate Interactions (Monitor Closely)

• Cimetidine: may increase metronidazole plasma levels.
• Phenytoin: may reduce metronidazole effectiveness.
• Carbamazepine: may lower metronidazole concentrations, requiring monitoring.