Drug interactions
Erythromycin base + Quinidine
Severity: Contraindicated
Erythromycin base and Quinidine: contraindicated interaction.
Last updated Sources: US FDA label
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
Erythromycin prolongs the QT interval and inhibits CYP3A4, the main route of quinidine metabolism. This raises quinidine levels and increases the risk of torsades de pointes.
What this interaction means in plain words
Erythromycin base and Quinidine are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two.
Why it happens
Additive QT prolongation plus CYP3A4 inhibition reducing quinidine clearance.
What to do
Avoid the combination and choose a non-macrolide antibiotic such as one without QT effects. If it cannot be avoided, monitor ECG and quinidine levels.
What to ask your pharmacist
- Is there an alternative to one of these two medicines for me?
- If both are essential, who is monitoring me and how often?
- Which symptoms mean I should stop and seek help straight away?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Erythromycin base and Quinidine, 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.
References
Other interactions of Quinidine
- Adagrasib + Quinidine Contraindicated
- Arsenic trioxide + Quinidine Contraindicated
- Artemether / lumefantrine + Quinidine Contraindicated
- Chloroquine + Quinidine Contraindicated
- Dofetilide + Quinidine Contraindicated
- Dronedarone + Quinidine Contraindicated
Frequently asked questions
Can I take Erythromycin base with Quinidine?
MediHelp rates the interaction as contraindicated. Erythromycin base and Quinidine are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two. Erythromycin prolongs the QT interval and inhibits CYP3A4, the main route of quinidine metabolism. This raises quinidine levels and increases the risk of torsades de pointes.
How serious is the interaction between Erythromycin base and Quinidine?
MediHelp rates it contraindicated, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination and choose a non-macrolide antibiotic such as one without QT effects. If it cannot be avoided, monitor ECG and quinidine levels.
What other medicines interact with Quinidine?
MediHelp also lists interactions of Quinidine with, for example, Adagrasib, Arsenic trioxide, Artemether / lumefantrine. The full list is on the Quinidine 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.
