Supplement stacks / Vitamin K + Warfarin
Can You Take Vitamin K with Warfarin?
Vitamin K and Warfarin: two interactions flagged, scored 3/10 (high risk). The count and score come from an AI-written analysis checked against our interaction rules, which can only make it stricter. Not medical advice.
Safety at a glance
This score comes from an AI-written analysis of the pair. Our interaction rules check it and can only make it stricter, never milder. Informational only: it can't account for your medications, conditions, or genetics.
What the AI-written analysis says
Taking Warfarin with Vitamin K can lead to significant interactions, as Vitamin K can counteract the anticoagulant effects of Warfarin, potentially increasing the risk of clotting. Careful monitoring of Vitamin K intake is essential for individuals on Warfarin therapy.
Warfarin is a prescription medication. This page describes publicly documented interactions — it can't see your dose, your other prescriptions, or your labs. Discuss any supplement with the prescriber or pharmacist who manages this medication before combining.
Known interactions
Vitamin K can reduce the effectiveness of Warfarin, leading to increased risk of thrombosis.
Changes in Vitamin K intake can lead to fluctuations in INR levels, necessitating frequent monitoring.
Vitamin K
From the AI-written analysis.
Vitamin K is a fat-soluble vitamin essential for blood clotting. It can interfere with anticoagulant medications like Warfarin.
Typical dosage: 90-120 mcg daily for adults, but should be individualized for those on Warfarin.
- No significant side effects at normal dietary levels; high doses may cause clotting issues.
- Consult healthcare provider before taking Vitamin K if on Warfarin.
- Monitor dietary intake to maintain consistent levels.
Warfarin
From the AI-written analysis.
Warfarin is an anticoagulant medication used to prevent blood clots. It requires careful monitoring due to its narrow therapeutic index.
Typical dosage: As prescribed or as directed on the label
- Bleeding
- Bruising
- Gastrointestinal upset
- Regular INR monitoring is essential.
- Avoid sudden changes in dietary Vitamin K intake.
Timing
No timing arrangement makes this combination safe — see the warnings above.
Recommendations
- Consult with a healthcare provider before making any changes to Vitamin K intake.
- Maintain a consistent level of Vitamin K in the diet to avoid fluctuations in INR.
Watch out for
- Warfarin works by blocking vitamin K, so vitamin K supplements (including K2 forms like MK-7 and many bone-health or multivitamin formulas) can blunt its effect and lower INR. CoQ10 is structurally related to vitamin K and has case reports of reduced warfarin response, while cranberry and goji have case reports of the opposite, with INR rising. The core issue is stability: starting, stopping, or changing the dose of any of these can swing INR in either direction. Keep intake consistent, tell the prescriber or anticoagulation clinic before any change, and expect INR to be checked more often around changes.
- Significant risk of clotting if Vitamin K intake is increased suddenly.
- Monitor INR levels closely when adjusting Vitamin K intake.
Frequently asked questions
Can you take Vitamin K and Warfarin together?
Vitamin K and Warfarin: two interactions flagged, scored 3/10 (high risk). The count and score come from an AI-written analysis checked against our interaction rules, which can only make it stricter. Not medical advice.
What score does the Vitamin K and Warfarin combination get?
The Vitamin K and Warfarin combination is scored 3/10 (high risk). The score comes from an AI-written analysis checked against our interaction rules, which can only make it stricter. Not medical advice. Always confirm with a healthcare professional.
When should you take Vitamin K and Warfarin?
No timing arrangement makes this combination safe — see the warnings above.
What should you watch out for when combining Vitamin K and Warfarin?
Warfarin works by blocking vitamin K, so vitamin K supplements (including K2 forms like MK-7 and many bone-health or multivitamin formulas) can blunt its effect and lower INR. CoQ10 is structurally related to vitamin K and has case reports of reduced warfarin response, while cranberry and goji have case reports of the opposite, with INR rising. The core issue is stability: starting, stopping, or changing the dose of any of these can swing INR in either direction. Keep intake consistent, tell the prescriber or anticoagulation clinic before any change, and expect INR to be checked more often around changes. Significant risk of clotting if Vitamin K intake is increased suddenly. Monitor INR levels closely when adjusting Vitamin K intake.
Check your full stack
Taking more than these two? Add everything you take, medicines included, to your list. We check each supplement on your list against the rest of it, and name anything we could not check. Free, and you don’t need an account.
Analyze my stackWhat your DNA adds
Some genes in a raw 23andMe or AncestryDNA file are linked to how the body handles nutrients. The DNA report says what yours are linked to and, where there is one, which blood test would tell you more.
See the DNA reportRelated combinations
Not medical advice
AI-written analysis generated August 10, 2026, checked by our interaction rules · How our analysis works