Warfarin and Aspirin Interaction
Drug interaction information between Warfarin and Aspirin.
Warfarin and Aspirin have a documented moderate interaction in FDA labeling.
FDA drug labeling documents a moderate-severity interaction between Warfarin and Aspirin. 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
Aspirin is an antiplatelet drug that adds to the blood-thinning effect of warfarin. Taking both together significantly increases your chance of having a serious bleeding event.
Warfarin Also Interacts With
- Fluoxetine major
- Tamoxifen major
- Ibuprofen moderate
- Diclofenac moderate
- Desvenlafaxine moderate
Aspirin Also Interacts With
- Atenolol major
- Fluoxetine major
- Ibandronate major
- Alendronate moderate
- Apixaban moderate
Frequently Asked Questions
What SPL severity band is on file for Warfarin + Aspirin?
Compiled FDA labeling labels this pair moderate. 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 Aspirin's 47. In the moderate band specifically: Warfarin has 28 (also Ibuprofen, Diclofenac, Desvenlafaxine, Vilazodone); Aspirin has 12 (also Alendronate, Apixaban, Desvenlafaxine, Dexamethasone).
What mechanism field is on file for Warfarin and Aspirin?
Aspirin is an antiplatelet drug that adds to the blood-thinning effect of warfarin. Taking both together significantly increases your chance of having a serious bleeding event.
Aspirin carries more major-labeled pairs than Warfarin
SPL source-record counts only. This page's band is moderate · classes on file: Warfarin (Vitamin K Antagonist (Anticoagulant)); Aspirin (Antiplatelet / NSAID).
Aspirin has 3 major-labeled pairs vs Warfarin's 2. This page itself is in the moderate band, not the major band.
2 major · 28 moderate · 133 minor · 163 total
- Other moderate peers for Warfarin
- Ibuprofen
- Diclofenac
- Desvenlafaxine
- Vilazodone
3 major · 12 moderate · 32 minor · 47 total
- Other moderate peers for Aspirin
- Alendronate
- Apixaban
- Desvenlafaxine
- Dexamethasone
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.