Cyclophosphamide and Warfarin: Drug Interaction Guide

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

How Cyclophosphamide interacts with Warfarin

Cyclophosphamide alters warfarin metabolism via CYP induction effects and chemotherapy-induced changes in vitamin K-dependent clotting factor synthesis, producing unpredictable INR shifts.

What you should do

Monitor INR twice weekly during chemotherapy cycles and adjust warfarin dose accordingly.

Key facts

Severity

Moderate — caution required

Mechanism

Cyclophosphamide alters warfarin metabolism via CYP induction effects and chemotherapy-induced changes in vitamin K-depe...

Action

Monitor INR twice weekly during chemotherapy cycles and adjust warfarin dose accordingly.

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 Cyclophosphamide and Warfarin together?

With caution. Monitor INR twice weekly during chemotherapy cycles and adjust warfarin dose accordingly.

What is the severity of this interaction?

The interaction between Cyclophosphamide and Warfarin is classified as Moderate — caution required. Cyclophosphamide alters warfarin metabolism via CYP induction effects and chemotherapy-induced changes in vitamin K-dependent clotting factor synthesis, producing unpredictable INR shifts.

What should I do if I'm prescribed both?

Monitor INR twice weekly during chemotherapy cycles and adjust warfarin dose accordingly. Always consult your prescribing clinician — do not stop or change medications without medical guidance.

Last reviewed: May 17, 2026 by iMedic Medical Editorial Team. Our editorial process.