Drug interactions
Erythromycin + Phenindione
Severity: Moderate
Erythromycin and Phenindione: 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
Erythromycin may enhance the anticoagulant effect of oral vitamin K antagonists, increasing the INR and bleeding risk. Evidence for phenindione specifically is limited, but the effect is documented for related anticoagulants.
What this interaction means in plain words
Erythromycin and Phenindione 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.
Why it happens
Erythromycin may inhibit hepatic metabolism of the anticoagulant and alter gut flora, although the mechanism for phenindione is not well established.
What to do
Monitor INR closely when starting or stopping erythromycin and adjust the phenindione dose as needed. Consider a non-interacting antibiotic.
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 Erythromycin and Phenindione, 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 Erythromycin
- Conivaptan + Erythromycin Contraindicated
- Dihydroergotamine intranasal + Erythromycin Contraindicated
- Dihydroergotamine + Erythromycin Contraindicated
- Domperidone + Erythromycin Contraindicated
- Dronedarone + Erythromycin Contraindicated
- Droperidol + Erythromycin Contraindicated
Frequently asked questions
Can I take Erythromycin with Phenindione?
MediHelp rates the interaction as moderate. Erythromycin and Phenindione 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. Erythromycin may enhance the anticoagulant effect of oral vitamin K antagonists, increasing the INR and bleeding risk. Evidence for phenindione specifically is limited, but the effect is documented for related anticoagulants.
How serious is the interaction between Erythromycin and Phenindione?
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 INR closely when starting or stopping erythromycin and adjust the phenindione dose as needed. Consider a non-interacting antibiotic.
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.
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.
