Letrozole and Warfarin Interaction
Drug interaction information between Letrozole and Warfarin.
Letrozole and Warfarin have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Letrozole and Warfarin. This page displays the available source-record category and label text. The category is not an individual risk estimate or medication-combination direction.
How They Interact
Research shows that letrozole does not change how the body handles the blood thinner warfarin. There is no major interaction between these two drugs.
FDA Label Information
Warfarin An interaction study (P017) with warfarin showed no clinically significant effect of letrozole on warfarin pharmacokinetics.
Letrozole Also Interacts With
- Tamoxifen moderate
- Cimetidine minor
- Letrozole (Fertility) minor
Warfarin Also Interacts With
- Fluoxetine major
- Tamoxifen major
- Ibuprofen moderate
- Aspirin moderate
- Diclofenac moderate
Frequently Asked Questions
What SPL severity band is on file for Letrozole + Warfarin?
Compiled FDA labeling labels this pair minor. That is a source-record field, not an individual medication-combination decision.
Which drug in this pair has the larger labeled-interaction portfolio?
Warfarin has 163 labeled pairs on file vs Letrozole's 4. In the minor band specifically: Letrozole has 3 (also Cimetidine, Letrozole); Warfarin has 133 (also Atorvastatin, Amlodipine, Omeprazole, Famotidine).
What mechanism field is on file for Letrozole and Warfarin?
Research shows that letrozole does not change how the body handles the blood thinner warfarin. There is no major interaction between these two drugs.
Warfarin carries more major-labeled pairs than Letrozole
SPL source-record counts only. This page's band is minor · classes on file: Letrozole (Aromatase Inhibitor); Warfarin (Vitamin K Antagonist (Anticoagulant)).
Warfarin has 2 major-labeled pairs vs Letrozole's 0. This page itself is in the minor band, not the major band.
0 major · 1 moderate · 3 minor · 4 total
- Other minor peers for Letrozole
- Cimetidine
- Letrozole
2 major · 28 moderate · 133 minor · 163 total
- Other minor peers for Warfarin
- Atorvastatin
- Amlodipine
- Omeprazole
- Famotidine
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. This registry does not provide individual medication-combination directions.
Read our methodology - how this data is sourced, computed, and verified.