NSTK · 01.2026Independent supplement reference
NutriStack
Edition 1.0Updated July 13, 2026

Metronidazole

Prescription ·Exploratory record · not publication-reviewed ·Updated July 13, 2026

A nitroimidazole antimicrobial with potent activity against anaerobic bacteria and certain protozoa. Alternative treatment for Clostridioides difficile infection when vancomycin or fidaxomicin is unavailable, bacterial vaginosis, trichomoniasis, amoebic dysentery, and anaerobic intra-abdominal/pelvic infections (typically combined with a cephalosporin or fluoroquinolone). Also used in combination regimens for H. pylori eradication.

Evidence tier
Strong
Indexed sources
10 1995–2025
Interactions
0
Depletes
1 nutrient
Read the sources → Compare profiles
Publication status

Exploratory record, not a reviewed medical publication.

See the editorial and medical-review policies for the publication gate.

This generated database record has not completed a claim-level review by a qualified human medical reviewer. Bibliography links and evidence labels are not approval. The page remains available for reference and is excluded from search indexing.

In short

What the research says.

A quick, data-only summary. The full evidence, dosing, and sources are below.

A nitroimidazole antimicrobial with potent activity against anaerobic bacteria and certain protozoa. NutriStack rates the supporting evidence as strong. Common adult dosing is 250-500 mg every 8 hours orally; C. diff: 500 mg TID x 10 days; bacterial vaginosis: 500 mg BID x 7 days; trichomoniasis: 2 g single dose (as prescribed by your physician), though a prescriber sets the actual dose. With long-term use it can deplete vitamin k. This profile indexes 10 sources.

What it's good for
  • Alternative treatment for C. difficile infection (when first-line agents unavailable)7,8
  • Treats bacterial vaginosis
  • Treats trichomoniasis
  • Treats amoebic dysentery and liver abscess
  • Treats anaerobic intra-abdominal and pelvic infections9
What to watch for
  • Metallic taste (very common)
  • Nausea and vomiting
  • Diarrhea
  • Known hypersensitivity to metronidazole or nitroimidazoles1,2
  • First trimester of pregnancy (for trichomoniasis, weigh risk/benefit)6

The bottom line

Evidence rating strong. Most-documented uses: alternative treatment for c. difficile infection (when first-line agents unavailable), treats bacterial vaginosis, treats trichomoniasis. 10 sources indexed (1995–2025), with 0 interaction records on file.

The science

How it works, mechanistically.

Core mechanism

A prodrug that is reduced inside anaerobic and microaerophilic organisms. The nitro group of metronidazole is reduced by ferredoxin (or flavodoxin) to form reactive cytotoxic intermediates, nitro radical anions, nitroso compounds, and hydroxylamine. These intermediates cause DNA strand breakage, helix destabilization, and inhibition of nucleic acid synthesis, leading to cell death. Selective toxicity to anaerobes results from their low-redox-potential electron transport systems required to activate the drug.

Class
Nitroimidazole Antibiotic/Antiprotozoal
Absorption
Water-soluble; take with food
Dosing

Dosing & protocol.

Common range
250-500 mg every 8 hours orally; C. diff: 500 mg TID x 10 days; bacterial vaginosis: 500 mg BID x 7 days; trichomoniasis: 2 g single dose (as prescribed by your physician)
Recommended form
Oral tablets, capsules, IV, topical gel, or vaginal gel

Oral bioavailability nearly 100%. Taking with food reduces GI upset. IMPORTANT: Avoid alcohol during treatment and for at least 3 days after, disulfiram-like reaction (nausea, vomiting, flushing, tachycardia).

Depletions

What it depletes.

Nutrients this medication can lower over time, and what to replace.

Vitamin K

Mild

Broad-spectrum antibiotic exposure can suppress gut bacteria that synthesize menaquinones, lowering vitamin K availability in susceptible patients.

Monitor PT/INROnset Usually with prolonged therapy, poor intake, or malabsorption

Full Metronidazole depletion and interaction guide →

Safety

Full safety detail.

Side effects

  • Metallic taste (very common)
  • Nausea and vomiting
  • Diarrhea
  • Disulfiram-like reaction with alcohol
  • Peripheral neuropathy (with prolonged use)
  • Darkening of urine (harmless metabolite)
  • Headache
  • Seizures (rare, with high doses or prolonged use)

Contraindications

  • Known hypersensitivity to metronidazole or nitroimidazoles1,2
  • First trimester of pregnancy (for trichomoniasis, weigh risk/benefit)6
  • Concurrent alcohol consumption (disulfiram-like reaction)
  • Concurrent disulfiram use (risk of psychotic reactions)
  • Concurrent use with lithium without monitoring (may increase lithium levels)
Sources

Sources, by evidence tier.

Numbered references. Citations throughout the page link here.

Meta-analyses & systematic reviews

6

Reference material

4
FAQ

Common questions.

Quick answers about Metronidazole, drawn from the data on this page.

What is Metronidazole?

A nitroimidazole antimicrobial with potent activity against anaerobic bacteria and certain protozoa. Alternative treatment for Clostridioides difficile infection when vancomycin or fidaxomicin is unavailable, bacterial vaginosis, trichomoniasis, amoebic dysentery, and anaerobic intra-abdominal/pelvic infections (typically combined with a cephalosporin or fluoroquinolone). Also used in combination regimens for H. pylori eradication.

What is Metronidazole used for?

Commonly cited benefits of Metronidazole include: Alternative treatment for C. difficile infection (when first-line agents unavailable); Treats bacterial vaginosis; Treats trichomoniasis; Treats amoebic dysentery and liver abscess; Treats anaerobic intra-abdominal and pelvic infections. NutriStack rates the overall evidence as strong.

What is a typical dose of Metronidazole?

A typical adult dose of Metronidazole is 250-500 mg every 8 hours orally; C. diff: 500 mg TID x 10 days; bacterial vaginosis: 500 mg BID x 7 days; trichomoniasis: 2 g single dose (as prescribed by your physician). The commonly recommended form is Oral tablets, capsules, IV, topical gel, or vaginal gel. These are general ranges, not personalized advice; confirm the right dose with a clinician.

What are the side effects of Metronidazole?

Reported side effects include metallic taste (very common), nausea and vomiting, diarrhea, disulfiram-like reaction with alcohol, peripheral neuropathy (with prolonged use), darkening of urine (harmless metabolite). This is educational information; check with a healthcare professional before use.

How strong is the evidence for Metronidazole?

NutriStack rates this as Strong, meaning multiple high-quality meta-analyses or systematic reviews converge on the same finding. Full tier criteria are at https://nutristackapp.com/methodology/evidence-tiers.

Use this with your stack

Metronidazole in NutriStack.

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NutriStack is an informational and organizational tool, not a medical service, and not a substitute for professional advice. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement or medication.