NutriStack
Coenzyme Q10 and Warfarin, a caution.
Coenzyme Q10 (ubiquinone) is structurally similar to vitamin K and may reduce warfarin's anticoagulant effect in some patients. Case reports describe loss of INR control after starting CoQ10. A longitudinal study of warfarin patients found CoQ10 use independently tripled the odds of bleeding events, so the direction of the interaction is not predictable. Effects appear most likely at doses of 100 mg/day or more.
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.
Every entry follows the same shape: what is happening, the mechanism, the recommendation, and the primary literature.
At a glance
- Substances
- Coenzyme Q10 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. Coenzyme Q10 (ubiquinone) is structurally similar to vitamin K and may reduce warfarin's anticoagulant effect in some patients. Case reports describe loss of INR control after starting CoQ10. A longitudinal study of warfarin patients found CoQ10 use independently tripled the odds of bleeding events, so the direction of the interaction is not predictable. Effects appear most likely at doses of 100 mg/day or more.
Mechanism. CoQ10 shares a quinone backbone with vitamin K and may partially substitute as a cofactor in clotting factor carboxylation. Microsomal studies also suggest CoQ10 can accelerate the hydroxylation and clearance of S- and R-warfarin via CYP2C9 and CYP3A4, lowering plasma warfarin levels.
Recommendation. Tell your anticoagulation clinic before starting, stopping, or changing the dose of CoQ10. If you do take it, keep the daily dose constant and ask for an INR check within 1-2 weeks of any change.
Sources (3)
- Landbo C, Almdal TP. Interaction between warfarin and coenzyme Q10. Ugeskr Laeger. 1998;160(22):3226-7. PMID 9621803
- Shalansky S, Lynd L, Richardson K, Ingaszewski A, Kerr C. Risk of warfarin-related bleeding events and supratherapeutic international normalized ratios associated with complementary and alternative medicine: a longitudinal analysis. Pharmacotherapy. 2007;27(9):1237-47. PMID 17723077
- Zhou Q, Zhou S, Chan E. Effect of coenzyme Q10 on warfarin hydroxylation in rat and human liver microsomes. Curr Drug Metab. 2005;6(2):67-81. PMID 15853759
Stack Score
How this pair moves the number.
Effect on the composite score
If both Coenzyme Q10 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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