Last reviewed 2026-04-23 · How we verify

Metronidazole 0.8%

Metronidazole is a nitroimidazole antibiotic that disrupts bacterial and parasitic DNA by generating reactive oxygen species after reduction of its nitro group.

Metronidazole is a nitroimidazole antibiotic that disrupts bacterial and parasitic DNA by generating reactive oxygen species after reduction of its nitro group. Used for Anaerobic bacterial infections (topical formulation), Parasitic infections (potential indication under investigation).

At a glance

Mechanism of action

Metronidazole is activated by anaerobic organisms and parasites through reduction of its 5-nitro group, generating short-lived reactive intermediates that damage DNA and inhibit nucleic acid synthesis. This mechanism is selective for anaerobic bacteria and certain parasites, making it effective against obligate anaerobes and protozoa while having minimal activity against aerobic organisms. The 0.8% topical formulation is designed for localized delivery to affected tissues.

Approved indications

• Anaerobic bacterial infections (topical formulation)
• Parasitic infections (potential indication under investigation)

Common side effects

• Metallic taste
• Nausea
• Headache
• Local irritation (topical)

Key clinical trials

• Effectiveness of Metronidazole Gel and Mobile SMS Reminders on Gingivitis in Orthodontic Patients (PHASE4)
• Comparative Evaluation of Chlorhexidine, Metronidazole and Combination Gels on Gingivitis (PHASE3)
• Tailored Therapy for Helicobacter Pylori in Children (PHASE4)
• Odor Management in Fungating Wounds Comparing Metronidazole and Polihexanide (PHASE3)
• Once Daily In-situ Forming Versus Twice-daily Conventional Metronidazole Vaginal Gels for Treatment of Bacterial Vaginosis (PHASE2, PHASE3)

Primary sources

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