Drug interactions
Methadone + Metronidazole
Severity: Moderate
Methadone 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 methadone concentrations, potentially causing sedation, respiratory depression or QT prolongation. Metronidazole itself has been associated with QT prolongation.
What this interaction means in plain words
Methadone 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.
Methadone belongs to Musculoskeletal; Metronidazole belongs to Anti Parasitic.
Why it happens
Possible inhibition of CYP-mediated methadone metabolism, with additive QT effects.
What to do
Monitor for excess opioid effects during metronidazole therapy and reduce the methadone dose if they occur. Consider an ECG in patients with other QT risk factors.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Methadone and Metronidazole, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
Other interactions of Methadone
- Alvimopan + Methadone Contraindicated
- Calcium / magnesium / potassium / sodium oxybates + Methadone Contraindicated
- Droperidol + Methadone Contraindicated
- Ibutilide + Methadone Contraindicated
- Isocarboxazid + Methadone Contraindicated
- Lefamulin + Methadone Contraindicated
Other interactions of Metronidazole
- Ethanol + Metronidazole Contraindicated
- Metronidazole + Pimozide Contraindicated
- Amiodarone + Metronidazole Major
- Disulfiram + Metronidazole Major
- Ergotamine + Metronidazole Major
- Lomitapide + Metronidazole Major
Frequently asked questions
Can I take Methadone with Metronidazole?
MediHelp rates the interaction as moderate. Methadone 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 methadone concentrations, potentially causing sedation, respiratory depression or QT prolongation. Metronidazole itself has been associated with QT prolongation.
How serious is the interaction between Methadone 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: Monitor for excess opioid effects during metronidazole therapy and reduce the methadone dose if they occur. Consider an ECG in patients with other QT risk factors.
What other medicines interact with Methadone?
MediHelp also lists interactions of Methadone with, for example, Alvimopan, Calcium / magnesium / potassium / sodium oxybates, Droperidol. The full list is on the Methadone page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
