Metronidazole Vaginal and Lithium: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Lithium
No brand names on recordMetronidazole Vaginal
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Increased lithium exposure and an increased risk of lithium toxicity (weakness, tremor, excessive thirst, confusion)
Interaction Deep Dive
Short-term concurrent use of oral metroNIDAZOLE in patients stabilized on relatively high doses of lithium, has been associated with elevated serum lithium levels and a few cases of lithium toxicity3. The suspected mechanism of interaction is reduced renal clearance of lithium 4. For patients on lithium therapy who start on oral metroNIDAZOLE, obtain serum creatinine and lithium levels several days after initiating metroNIDAZOLE therapy 32 to detect any increase that may precede clinical symptoms of lithium toxicity 1. For patients on lithium therapy starting on metroNIDAZOLE, consider monitoring serum lithium levels 52.
Why it happens (mechanism)
Reduced renal clearance of lithium
Literature reports
1 report — tap to read
a) Two case reports have demonstrated that the concurrent use of metroNIDAZOLE (greater than or equal to 750 mg daily) and lithium may result in increased lithium exposure and toxicity. Persistent signs of renal damage were evident 5 to 6 months after discontinuation of metroNIDAZOLE therapy 6.
Common questions
Can I take Metronidazole Vaginal and Lithium together?
Increased lithium exposure and an increased risk of lithium toxicity (weakness, tremor, excessive thirst, confusion) Always confirm with your pharmacist or prescriber before making any change.
How serious is the Metronidazole Vaginal and Lithium interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Metronidazole Vaginal or Lithium need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (6)
- Product Information: LIKMEZ(TM) oral suspension, metronidazole oral suspension. Saptalis Pharmaceuticals LLC (per FDA), Hauppauge, NY, 2023. DailyMed
- Product Information: PYLERA(R) oral capsules, bismuth subcitrate potassium, metronidazole, tetracycline HCl oral capsules. H2-Pharma, LLC (per FDA), Montgomery, AL, 2025. DailyMed
- Product Information: Flagyl(R) oral tablets, metronidazole oral tablets. G.D. Searle LLC, New York, NY, 2010. DailyMed
- Product Information: LITHOBID(R) extended-release oral tablets, lithium carbonate extended-release oral tablets. Noven Therapeutics, LLC, Miami, FL, 2009. DailyMed
- Product Information: VANDAZOLE(R) vaginal gel, metronidazole vaginal gel. Upsher-Smith Laboratories, Inc, Minneapolis, MN, 2011. DailyMed
- Teicher MH, Altesman RI, Cole JO, et al: Possible nephrotoxic interaction of lithium and metronidazole (letter). JAMA 1987; 257:3365-3366. DOI
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