Valproic Acid and Warfarin: Drug Interaction Guide

Quick answer: This combination requires caution. Valproic Acid and Warfarin can be used together with adjustments and monitoring.

Interaction severity: Moderate — caution required

How Valproic Acid interacts with Warfarin

Valproate displaces warfarin from plasma albumin and inhibits CYP2C9 metabolism, transiently increasing free warfarin and INR.

What you should do

Monitor INR closely when valproate is initiated, dose adjusted or stopped and modify warfarin dose as required.

Key facts

Severity

Moderate — caution required

Mechanism

Valproate displaces warfarin from plasma albumin and inhibits CYP2C9 metabolism, transiently increasing free warfarin an...

Action

Monitor INR closely when valproate is initiated, dose adjusted or stopped and modify warfarin dose as required.

Important medical disclaimer: This page provides educational information about drug interactions for general reference. It is not a substitute for professional medical advice, diagnosis, or treatment. Always discuss your specific medications with a qualified healthcare provider before starting, stopping, or changing any treatment. About our editorial team.

Frequently asked questions

Can I take Valproic Acid and Warfarin together?

With caution. Monitor INR closely when valproate is initiated, dose adjusted or stopped and modify warfarin dose as required.

What is the severity of this interaction?

The interaction between Valproic Acid and Warfarin is classified as Moderate — caution required. Valproate displaces warfarin from plasma albumin and inhibits CYP2C9 metabolism, transiently increasing free warfarin and INR.

What should I do if I'm prescribed both?

Monitor INR closely when valproate is initiated, dose adjusted or stopped and modify warfarin dose as required. Always consult your prescribing clinician — do not stop or change medications without medical guidance.

Last reviewed: by iMedic Medical Editorial Team. Our editorial process.