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Entacapone and Warfarin Interaction

Drug interaction information between Entacapone and Warfarin.

Entacapone and Warfarin have a documented minor interaction in FDA labeling.

FDA drug labeling documents a minor-severity interaction between Entacapone and Warfarin. Major interactions are generally avoided, moderate ones may need monitoring or a dose adjustment, and minor ones are usually low-risk. This page shows the documented mechanism and guidance. Label-documented interactions are not a complete safety review, so always confirm your own medications with a pharmacist or doctor. Educational information, not medical advice.

Drug A

Entacapone

COMT Inhibitor

Drug B

Warfarin

Vitamin K Antagonist (Anticoagulant)

How They Interact

Entacapone can increase the levels of warfarin in your system, which may cause your blood to become too thin.

What To Do

Your doctor should monitor your blood clotting levels (INR) closely when you start entacapone or change your dose.

FDA Label Information

In an interaction study in healthy volunteers, entacapone did not significantly change the plasma levels of S-warfarin while the AUC for R-warfarin increased on average by 18% [Cl90 11% to 26%], and the INR values increased on average by 13% [Cl90 6% to 19%]. Nevertheless, cases of significantly increased INR in patients concomitantly using warfarin have been reported during the postapproval use of entacapone. Therefore, monitoring of INR is recommended when entacapone treatment is initiated or when the dose is increased for patients receiving warfarin.

Warfarin Also Interacts With

View all Warfarin interactions →

Frequently Asked Questions

Can I take Entacapone and Warfarin together?

This is a minor interaction. Your doctor should monitor your blood clotting levels (INR) closely when you start entacapone or change your dose.

How serious is the interaction between Entacapone and Warfarin?

This interaction is classified as "minor" severity by the FDA. Minor interactions are unlikely to cause significant problems but should still be mentioned to your healthcare provider.

Why do Entacapone and Warfarin interact?

Entacapone can increase the levels of warfarin in your system, which may cause your blood to become too thin.

Understanding the Entacapone and Warfarin Interaction

FDA-approved prescribing information for these two drugs flags their combination as a minor-severity interaction. Entacapone belongs to the COMT Inhibitor class and Warfarin belongs to the Vitamin K Antagonist (Anticoagulant) class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Entacapone can increase the levels of warfarin in your system, which may cause your blood to become too thin. Severity tiers matter: major flags generally advise avoidance, moderate flags often require monitoring or dose adjustment, and minor flags may only call for awareness.

Context around a specific patient determines real-world impact. Entacapone has 3 total documented interactions on file in this dataset, and Warfarin has 163. Each additional medication compounds the interaction surface, which is why pharmacists run full-profile checks rather than evaluating one pair at a time. FDA-derived guidance for this pair is: Your doctor should monitor your blood clotting levels (INR) closely when you start entacapone or change your dose. Timing of doses, renal and hepatic function, age, and other concurrent prescriptions all shape whether a labeled interaction matters clinically.

An interaction flag is not a verdict. A large share of labeled interactions are managed routinely in clinical practice, the fix may be as simple as spacing doses or adding a monitoring test. Others require the prescriber to choose a different medication entirely. This page surfaces FDA-sourced labeling and openFDA data for educational purposes only; it is not medical advice and cannot account for your full clinical picture. Never start, stop, or adjust either Entacapone or Warfarin based on a web page, speak with your prescriber or pharmacist before making any change.

Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. Always consult your healthcare provider about drug interactions.