NutriStack
Turmeric/Curcumin and Warfarin, a caution.
Curcumin may inhibit platelet aggregation and has shown anticoagulant properties in vitro and in animal studies. When combined with warfarin, there is a theoretical and clinically reported risk of enhanced anticoagulation and bleeding. Case reports have documented elevated INR in patients adding turmeric to warfarin therapy.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
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At a glance
- Substances
- Turmeric/Curcumin and Warfarin
- Pair type
- Caution
- Evidence (highest tier)
- Moderate
- Source citations
- 3 sources
- Stack Score effect
- −5 to your Stack Score (per scored caution row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Caution · Moderate evidence
Caution
What is happening. Curcumin may inhibit platelet aggregation and has shown anticoagulant properties in vitro and in animal studies. When combined with warfarin, there is a theoretical and clinically reported risk of enhanced anticoagulation and bleeding. Case reports have documented elevated INR in patients adding turmeric to warfarin therapy.
Mechanism. Curcumin inhibits platelet aggregation by blocking thromboxane A2 synthesis and calcium signaling in platelets. It may also inhibit CYP1A2 and CYP2C9 enzymes involved in warfarin metabolism, potentially increasing warfarin plasma concentrations.
Recommendation. Use caution when combining turmeric/curcumin supplements with warfarin. Culinary turmeric in food is generally safe, but concentrated curcumin supplements should be discussed with your prescriber. Monitor INR if adding or removing curcumin.
Sources (3)
- Shah BH et al. Inhibitory effect of curcumin on platelet aggregation. Biochem Pharmacol. 1999;58(7):1167-1172. PMID 10484074
- Kim DC et al. Curcumin inhibits warfarin metabolism by inhibiting CYP2C9. J Nat Prod. 2012. PMID 22448682
- Wang M, Zeraatkar D, Obeda M, Lee M et al.. Drug-drug interactions with warfarin: A systematic review and meta-analysis. British Journal of Clinical Pharmacology. 2021. PMID 33769581
Stack Score
How this pair moves the number.
Effect on the composite score
If both Turmeric/Curcumin 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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