Drug interactions
Azathioprine + Warfarin
Severity: Moderate
Azathioprine 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
Azathioprine has been reported to reduce the anticoagulant effect of warfarin, leading to a lower INR. Loss of control may increase the risk of thromboembolism, and the INR may rise again when azathioprine is stopped.
What this interaction means in plain words
Azathioprine 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.
Azathioprine belongs to Gastrointestinal Tract; Warfarin belongs to Cardiovascular.
Why it happens
Mechanism is not established; possible induction of warfarin metabolism.
What to do
Monitor INR closely when starting or stopping azathioprine and increase warfarin dose as needed, reducing it again after azathioprine withdrawal.
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 Azathioprine
- Adenovirus types 4 and 7 live + Azathioprine Contraindicated
- Azathioprine + Bcg vaccine live Contraindicated
- Azathioprine + Febuxostat Contraindicated
- Azathioprine + Influenza virus vaccine quadrivalent intranasal Contraindicated
- Azathioprine + Measles mumps and rubella vaccine Contraindicated
- Azathioprine + Measles mumps and rubella vaccine live Contraindicated
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 Azathioprine with Warfarin?
MediHelp rates the interaction as moderate. Azathioprine 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. Azathioprine has been reported to reduce the anticoagulant effect of warfarin, leading to a lower INR. Loss of control may increase the risk of thromboembolism, and the INR may rise again when azathioprine is stopped.
How serious is the interaction between Azathioprine 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: Monitor INR closely when starting or stopping azathioprine and increase warfarin dose as needed, reducing it again after azathioprine withdrawal.
What other medicines interact with Azathioprine?
MediHelp also lists interactions of Azathioprine with, for example, Adenovirus types 4 and 7 live, Bcg vaccine live, Febuxostat. The full list is on the Azathioprine page.
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