Drug interactions
Cyclophosphamide + Warfarin
Severity: Moderate
Cyclophosphamide and Warfarin: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Cyclophosphamide and other chemotherapy can unpredictably change the anticoagulant response to warfarin, with reports of both raised and lowered INR. Cytopenia, poor oral intake, liver changes and antiemetics can add to this variability and to the bleeding risk.
What this interaction means in plain words
Cyclophosphamide and Warfarin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Cyclophosphamide belongs to Oncology; Warfarin belongs to Cardiovascular.
Why it happens
Variable alteration of warfarin response, probably through effects on hepatic function, nutrition and protein binding; not fully established.
What to do
Check INR more frequently when starting or stopping chemotherapy cycles and adjust the warfarin dose accordingly. Monitor platelet counts for bleeding risk.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Cyclophosphamide
Other interactions of Warfarin
- Defibrotide + Warfarin Contraindicated
- Ketorolac + Warfarin Contraindicated
- Abciximab + Warfarin Major
- Acetylsalicylic acid + Warfarin Major
- Adagrasib + Warfarin Major
- Amiodarone + Warfarin Major
Frequently asked questions
Can I take Cyclophosphamide with Warfarin?
MediHelp rates the interaction as moderate. Cyclophosphamide and Warfarin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Cyclophosphamide and other chemotherapy can unpredictably change the anticoagulant response to warfarin, with reports of both raised and lowered INR. Cytopenia, poor oral intake, liver changes and antiemetics can add to this variability and to the bleeding risk.
How serious is the interaction between Cyclophosphamide and Warfarin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check INR more frequently when starting or stopping chemotherapy cycles and adjust the warfarin dose accordingly. Monitor platelet counts for bleeding risk.
What other medicines interact with Cyclophosphamide?
MediHelp also lists interactions of Cyclophosphamide with, for example, Adenovirus types 4 and 7 live, Belatacept, Bendamustine. The full list is on the Cyclophosphamide page.
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