Drug interactions
Erythromycin + Metronidazole
Severity: Minor
Erythromycin and Metronidazole: minor 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
Both drugs have been linked to QT prolongation in case reports, and combined use may add to this risk. Metronidazole is not a recognized significant inhibitor of erythromycin metabolism.
What this interaction means in plain words
Erythromycin and Metronidazole have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Erythromycin belongs to Anti Bacterial; Metronidazole belongs to Anti Parasitic.
Why it happens
Possible additive QT effects; no established pharmacokinetic mechanism.
What to do
No routine adjustment is required. Consider an ECG and electrolyte check in patients with other QT risk factors.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Erythromycin
- Conivaptan + Erythromycin Contraindicated
- Dihydroergotamine intranasal + Erythromycin Contraindicated
- Dihydroergotamine + Erythromycin Contraindicated
- Domperidone + Erythromycin Contraindicated
- Dronedarone + Erythromycin Contraindicated
- Droperidol + Erythromycin 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 Erythromycin with Metronidazole?
MediHelp rates the interaction as minor. Erythromycin and Metronidazole have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Both drugs have been linked to QT prolongation in case reports, and combined use may add to this risk. Metronidazole is not a recognized significant inhibitor of erythromycin metabolism.
How serious is the interaction between Erythromycin and Metronidazole?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No routine adjustment is required. Consider an ECG and electrolyte check in patients with other QT risk factors.
What other medicines interact with Erythromycin?
MediHelp also lists interactions of Erythromycin with, for example, Conivaptan, Dihydroergotamine intranasal, Dihydroergotamine. The full list is on the Erythromycin page.
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