Drug interactions
Lithium + Metronidazole
Severity: Moderate
Lithium and Metronidazole: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Metronidazole has been reported to raise serum lithium concentrations, in some cases leading to lithium toxicity with tremor, confusion, nausea or ataxia. Because lithium has a narrow therapeutic index, even a modest rise can be clinically important.
What this interaction means in plain words
Lithium and Metronidazole can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Lithium belongs to Central Nervous System; Metronidazole belongs to Anti Parasitic.
Why it happens
The mechanism is not firmly established; reduced renal lithium clearance has been suggested.
What to do
Measure serum lithium before and several days after starting metronidazole, and adjust the lithium dose as needed. Counsel the patient to report signs of lithium toxicity promptly.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Metronidazole
- Ethanol + Metronidazole Contraindicated
- Metronidazole + Pimozide Contraindicated
- Amiodarone + Metronidazole Major
- Disulfiram + Metronidazole Major
- Ergotamine + Metronidazole Major
- Lomitapide + Metronidazole Major
Other interactions of Lithium
- Lithium + Thioridazine Contraindicated
- Lithium + Vandetanib Contraindicated
- Aceclofenac + Lithium Major
- Acemetacin + Lithium Major
- Amisulpride + Lithium Major
- Amlodipine-benazepril + Lithium Major
Frequently asked questions
Can I take Lithium with Metronidazole?
MediHelp rates the interaction as moderate. Lithium and Metronidazole can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Metronidazole has been reported to raise serum lithium concentrations, in some cases leading to lithium toxicity with tremor, confusion, nausea or ataxia. Because lithium has a narrow therapeutic index, even a modest rise can be clinically important.
How serious is the interaction between Lithium and Metronidazole?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Measure serum lithium before and several days after starting metronidazole, and adjust the lithium dose as needed. Counsel the patient to report signs of lithium toxicity promptly.
What other medicines interact with Metronidazole?
MediHelp also lists interactions of Metronidazole with, for example, Ethanol, Pimozide, Amiodarone. The full list is on the Metronidazole page.
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