Clarithromycin and Warfarin: Drug Interaction Guide
Quick answer: This is a major interaction — avoid combining Clarithromycin and Warfarin unless specifically directed by your doctor.
How Clarithromycin interacts with Warfarin
Clarithromycin inhibits CYP3A4 and CYP1A2 metabolism of warfarin and disturbs gut flora producing vitamin K, potentiating anticoagulant effect.
What you should do
Monitor INR within 3-5 days of starting clarithromycin and adjust warfarin dose; consider azithromycin as a lower-risk alternative.
Key facts
Severity
Major — avoid combination
Mechanism
Clarithromycin inhibits CYP3A4 and CYP1A2 metabolism of warfarin and disturbs gut flora producing vitamin K, potentiatin...
Action
Monitor INR within 3-5 days of starting clarithromycin and adjust warfarin dose; consider azithromycin as a lower-risk a...
Frequently asked questions
Can I take Clarithromycin and Warfarin together?
No — this combination should generally be avoided. Monitor INR within 3-5 days of starting clarithromycin and adjust warfarin dose; consider azithromycin as a lower-risk alternative.
What is the severity of this interaction?
The interaction between Clarithromycin and Warfarin is classified as Major — avoid combination. Clarithromycin inhibits CYP3A4 and CYP1A2 metabolism of warfarin and disturbs gut flora producing vitamin K, potentiating anticoagulant effect.
What should I do if I'm prescribed both?
Monitor INR within 3-5 days of starting clarithromycin and adjust warfarin dose; consider azithromycin as a lower-risk alternative. Always consult your prescribing clinician — do not stop or change medications without medical guidance.
Last reviewed: by iMedic Medical Editorial Team. Our editorial process.