Drug interactions
Losartan + Warfarin
Severity: Minor
Losartan and Warfarin: minor 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
Losartan is a CYP2C9 substrate, but no consistent clinically significant effect on warfarin exposure or INR has been shown. A small effect is possible in some patients.
What this interaction means in plain words
Losartan and Warfarin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Losartan belongs to Cardiovascular; Warfarin belongs to Cardiovascular.
Why it happens
Possible competition for CYP2C9 metabolism, though a meaningful inhibitory effect has not been established.
What to do
Check INR after starting or stopping losartan as part of routine warfarin monitoring.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Losartan
- Aliskiren + Losartan Contraindicated
- Losartan + Sparsentan Contraindicated
- Amifostine + Losartan Major
- Amiloride + Losartan Major
- Amlodipine-benazepril + Losartan Major
- Amlodipine-hydrochlorothiazide-valsartan + Losartan Major
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 Losartan with Warfarin?
MediHelp rates the interaction as minor. Losartan and Warfarin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Losartan is a CYP2C9 substrate, but no consistent clinically significant effect on warfarin exposure or INR has been shown. A small effect is possible in some patients.
How serious is the interaction between Losartan and Warfarin?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check INR after starting or stopping losartan as part of routine warfarin monitoring.
What other medicines interact with Losartan?
MediHelp also lists interactions of Losartan with, for example, Aliskiren, Sparsentan, Amifostine. The full list is on the Losartan page.
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