NutriStack
Fenugreek and Warfarin, a caution.
Fenugreek aqueous extract inhibits coagulation in vitro and significantly prolongs prothrombin time. A well-documented case describes a warfarin-stable patient whose INR rose after starting boldo and fenugreek, normalised after stopping, then rose again on rechallenge. Fenugreek's coumarin content is the suspected driver.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
Same shape as the other 1,729 pairs in the public database.
From the interaction database
What the row says.
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At a glance
- Pair type
- Caution
- Evidence (highest tier)
- Emerging
- Source citations
- 2 sources
- Stack Score effect
- −5 to your Stack Score (per scored caution row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Caution · Emerging evidence
Caution
What is happening. Fenugreek aqueous extract inhibits coagulation in vitro and significantly prolongs prothrombin time. A well-documented case describes a warfarin-stable patient whose INR rose after starting boldo and fenugreek, normalised after stopping, then rose again on rechallenge. Fenugreek's coumarin content is the suspected driver.
Mechanism. Fenugreek contains coumarin compounds that may have intrinsic anticoagulant activity additive to warfarin. Aqueous extracts have been shown to dose-dependently prolong prothrombin time, suggesting direct inhibition of vitamin K-dependent factors.
Recommendation. Avoid fenugreek supplements while on warfarin. Culinary use of small amounts of fenugreek seeds in food is unlikely to cause problems. Tell your anticoagulation clinic before starting any fenugreek supplement and ask for an INR check within 1-2 weeks.
Stack Score
How this pair moves the number.
Effect on the composite score
If both Fenugreek and Warfarin are in the same stack, this pair applies −5 to your Stack Score (per scored caution row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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