Co Trimoxazole and Warfarin: Drug Interaction Guide

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

Interaction severity: Moderate — caution required

How Co Trimoxazole interacts with Warfarin

Sulfamethoxazole inhibits CYP2C9-mediated metabolism of S-warfarin, while antimicrobial effects on intestinal vitamin K production may further increase INR.

What you should do

Prefer an alternative antibiotic when suitable. If combined, consider warfarin dose adjustment and check INR within several days and again after antibiotic completion.

Key facts

Severity

Moderate — caution required

Mechanism

Sulfamethoxazole inhibits CYP2C9-mediated metabolism of S-warfarin, while antimicrobial effects on intestinal vitamin K ...

Action

Prefer an alternative antibiotic when suitable. If combined, consider warfarin dose adjustment and check INR within seve...

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 Co Trimoxazole and Warfarin together?

With caution. Prefer an alternative antibiotic when suitable. If combined, consider warfarin dose adjustment and check INR within several days and again after antibiotic completion.

What is the severity of this interaction?

The interaction between Co Trimoxazole and Warfarin is classified as Moderate — caution required. Sulfamethoxazole inhibits CYP2C9-mediated metabolism of S-warfarin, while antimicrobial effects on intestinal vitamin K production may further increase INR.

What should I do if I'm prescribed both?

Prefer an alternative antibiotic when suitable. If combined, consider warfarin dose adjustment and check INR within several days and again after antibiotic completion. Always consult your prescribing clinician — do not stop or change medications without medical guidance.

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