NutriStack
Fish Oil and Warfarin, a caution.
Fish oil may potentiate warfarin's anticoagulant effect through its own antiplatelet and antithrombotic properties. While moderate doses (1-2g/day) appear relatively safe, higher doses can increase bleeding time and potentially elevate INR. Clinical bleeding events have been reported in case studies.
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.
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What the row says.
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At a glance
- Pair type
- Caution
- Evidence (highest tier)
- Moderate
- Source citations
- 6 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. Fish oil may potentiate warfarin's anticoagulant effect through its own antiplatelet and antithrombotic properties. While moderate doses (1-2g/day) appear relatively safe, higher doses can increase bleeding time and potentially elevate INR. Clinical bleeding events have been reported in case studies.
Mechanism. EPA and DHA reduce platelet aggregation by competing with arachidonic acid for cyclooxygenase, decreasing thromboxane A2 production. They also reduce blood viscosity and may modestly affect vitamin K-dependent coagulation factors.
Recommendation. If combining fish oil with warfarin, start with low doses (1g/day or less) and monitor INR closely during the first few weeks. Report any signs of unusual bleeding or bruising to your healthcare provider.
Sources (6)
- Buckley MS, Goff AD, Knapp WE. Fish oil interaction with warfarin. Ann Pharmacother. 2004;38(1):50-52. PMID 14742793
- Bays HE. Safety considerations with omega-3 fatty acid therapy. Am J Cardiol. 2007;99(6A):35C-43C. PMID 17368277
- 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
- Liao Y, Xie B, Zhang H et al.. Efficacy of omega-3 PUFAs in depression: A meta-analysis.. Translational Psychiatry. 2019. PMID 31383846
- Wei BZ, Li L, Dong CW et al.. The Relationship of Omega-3 Fatty Acids with Dementia and Cognitive Decline: Evidence from Prospective Cohort Studies of Supplementation, Dietary Intake, and Blood Markers.. American Journal of Clinical Nutrition. 2023. PMID 37028557
- Uchida Y, Tsuji K, Ochi E. Effects of Omega-3 fatty acids supplementation and resistance training on skeletal muscle.. Clinical Nutrition ESPEN. 2024. PMID 38777432
Stack Score
How this pair moves the number.
Effect on the composite score
If both Fish Oil 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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