Drug interactions
Azithromycin + Phenindione
Severity: Moderate
Azithromycin 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
Macrolide antibiotics including azithromycin have been reported to increase the anticoagulant effect of vitamin K antagonists. This may raise the INR and the risk of bleeding.
What this interaction means in plain words
Azithromycin 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
Mechanism not firmly established; possible changes in gut flora affecting vitamin K or reduced anticoagulant clearance.
What to do
Check the INR within a few days of starting azithromycin and adjust the phenindione dose accordingly. Counsel the patient on signs of bleeding.
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 Azithromycin
- Azithromycin + Cisapride Contraindicated
- Azithromycin + Domperidone Contraindicated
- Azithromycin + Dronedarone Contraindicated
- Azithromycin + Pimozide Contraindicated
- Azithromycin + Piperaquine Contraindicated
- Azithromycin + Thioridazine Contraindicated
Frequently asked questions
Can I take Azithromycin with Phenindione?
MediHelp rates the interaction as moderate. Azithromycin 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. Macrolide antibiotics including azithromycin have been reported to increase the anticoagulant effect of vitamin K antagonists. This may raise the INR and the risk of bleeding.
How serious is the interaction between Azithromycin 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: Check the INR within a few days of starting azithromycin and adjust the phenindione dose accordingly. Counsel the patient on signs of bleeding.
What other medicines interact with Azithromycin?
MediHelp also lists interactions of Azithromycin with, for example, Cisapride, Domperidone, Dronedarone. The full list is on the Azithromycin page.
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