Can You Take Vitamin K2 With Blood Thinners Like Eliquis?
It depends on which blood thinner you take. On warfarin or a similar drug, vitamin K2 works against the medicine, and in one study as little as 10 mcg a day lowered the INR enough to matter in at least 40% of people. Eliquis (apixaban) does not work through vitamin K, so K2 has no known way to weaken it, although no study has tested the two together.
Blood thinners come in two main families. The older family, vitamin K antagonists, includes warfarin (Coumadin) and acenocoumarol. These drugs work by blocking vitamin K, so extra vitamin K pushes back against them. The newer family, called direct oral anticoagulants or DOACs, includes apixaban (Eliquis), rivaroxaban (Xarelto), edoxaban and dabigatran. They block a clotting protein directly and do not depend on vitamin K at all. That one difference drives everything below.
What the Data Show
The key study is a dose-response trial in healthy volunteers. Eighteen healthy men and women took acenocoumarol, a close cousin of warfarin, for 4 weeks, and 15 of them reached a target INR of 2.0. The INR is the blood test that tracks how thin your blood is on these drugs: a normal value is about 1, and most people on warfarin aim for 2 to 3. Over the next 6 weeks, the volunteers kept the same drug dose and added rising doses of MK-7, the most common supplement form of vitamin K2: 10, then 20, then 45 mcg a day.
At 45 mcg a day, a common retail dose, the average INR fell by about 40%. At 20 mcg a day, two blood specialists judged the INR drop clinically relevant in at least 60% of people. At 10 mcg a day, they judged it clinically relevant in at least 40%. A falling INR means the blood is clotting more easily, which is the opposite of what the drug is there to do.
The authors concluded that MK-7 supplements need to be avoided in people taking vitamin K antagonists.
Is Vitamin K2 a Blood Thinner?
No. Vitamin K2 is not a blood thinner, and in people who are not on an anticoagulant it does not make blood clot more either.
Vitamin K helps the liver finish building several clotting proteins. Once those proteins are fully made, more vitamin K does not push them higher. Two studies tested this directly. In a study of 40 healthy adults, 90 mcg of MK-7 a day for 30 days did not change standard clotting tests or the activity of the vitamin K clotting factors. In a placebo-controlled trial of 123 people on dialysis, 360 mcg of MK-7 a day for a full year had no detectable effect on clotting markers, vascular events or death.
A US Pharmacopeia safety review concluded that MK-7 taken as a dietary supplement is not associated with any serious risk to health.
So the worry is not that K2 thickens normal blood. The worry is that it cancels part of a drug that is designed to block vitamin K.
Why Does Vitamin K2 Interfere With Warfarin?
Warfarin and acenocoumarol work by shutting down the recycling of vitamin K in the liver. Without usable vitamin K, the liver makes clotting proteins that do not work well, and the blood clots more slowly. Swallowing extra vitamin K hands the liver a fresh supply and undoes part of that block.
MK-7 is especially strong at this because it stays in the body so long. A study comparing vitamin K1 with MK-7 found that MK-7 has a very long half-life, giving much steadier blood levels, and that it built up to levels 7 to 8 times higher with daily use. The same paper warned that preparations supplying 50 mcg a day or more of MK-7 may interfere with oral anticoagulant treatment in a clinically relevant way. The later dose-response trial showed the effect starts well below that.
Food counts too. Natto, a Japanese fermented soybean dish, is the richest food source of MK-7. A study of a specially bred low-MK-7 natto states that regular natto must be avoided by people on warfarin. The new version, with 19% to 24% of the usual MK-7, did not change the INR in 10 warfarin patients at up to 20 grams a day.
Can You Take Vitamin K2 With Warfarin?
Not on your own. Starting, stopping or changing a K2 supplement on warfarin can swing your INR, and a low INR raises the risk of a clot or stroke.
There is one narrow exception, and it is managed by the anticoagulation team, not the patient. Some people on warfarin have an INR that bounces around for no clear reason. In a randomized trial of 70 such patients, a small fixed daily dose of 150 mcg of oral vitamin K improved stability. Time in the target range rose by 28 percentage points with vitamin K against 15 with placebo.
The wider evidence is weaker. A meta-analysis of 3 trials with 626 patients found only a 3.5 percentage-point gain in time in range, which the authors called clinically unimportant, and no proven effect on bleeding or clots. These trials did not use MK-7. If a fixed dose of vitamin K is ever added to warfarin, the warfarin dose is set around it and the INR is checked closely afterward.
Do I Need to Avoid Vitamin K Foods on Warfarin?
No, and cutting out green vegetables is not the point. A systematic review of 11 studies found that restricting vitamin K in the diet does not seem to improve warfarin control. An effect on clotting showed up mainly at high intakes, above 150 mcg a day of vitamin K1. The authors suggested that keeping your diet steady, without wide swings in vitamin K, matters more.
Can You Take Vitamin K2 With Eliquis?
Eliquis (apixaban) blocks a clotting protein called factor Xa directly. It does not touch the vitamin K cycle, so vitamin K2 has no known way to switch it off, and an INR test does not measure its effect.
No study has tested vitamin K2 together with apixaban. The closest evidence comes from rivaroxaban (Xarelto), which blocks factor Xa the same way. In the Valkyrie trial, 132 people on dialysis with atrial fibrillation were randomly assigned to a vitamin K antagonist, rivaroxaban, or rivaroxaban plus high-dose vitamin K2 (2,000 mcg three times a week) for 18 months. Strokes, heart events and deaths were similar across the groups.
Longer follow-up of the same trial found that fatal and nonfatal heart and blood vessel events occurred at 63.8 per 100 person-years on the vitamin K antagonist, 26.2 on rivaroxaban, and 21.4 on rivaroxaban plus vitamin K2. That was about 66% lower risk with rivaroxaban plus K2 and about 59% lower with rivaroxaban alone, compared with the vitamin K antagonist. Stroke rates did not differ between groups. Adding a large dose of K2 to a factor Xa blocker did not lead to more strokes or heart events.
Two cautions. That trial was in dialysis patients, and it used rivaroxaban, not apixaban. And a review of diet and blood thinners notes that whether dietary vitamin K affects the response to DOACs in humans remains to be investigated. So tell whoever prescribes your Eliquis about any supplement you take, but K2 is not in the same category of risk as it is with warfarin.
Does Vitamin K2 Help Bones or Arteries Enough to Be Worth the Risk?
On warfarin, the trade does not look good. In the dose-response trial, MK-7 doses that lowered the INR did not change the blood markers of vitamin K activity in bone (uncarboxylated osteocalcin) or in blood vessels (desphospho-uncarboxylated matrix Gla protein). The INR moved, but those markers did not.
In the Valkyrie trial, high-dose vitamin K2 improved vitamin K status but had no significant effect on how fast calcium built up in the arteries and heart valves.
Dr. Kumar’s Take
This is one of the few supplement questions with a clean answer, and the answer splits by drug. Warfarin works by starving the liver of vitamin K. Vitamin K2, especially MK-7, refills that supply and lingers in the blood. At 10 mcg, under a quarter of the usual 45 mcg retail dose, it already moved the INR in a meaningful share of people. K2 also turns up in multivitamins, bone formulas and “D3 plus K2” products, so labels matter.
Eliquis is different. It does not depend on vitamin K, and the one trial that paired a factor Xa blocker with high-dose K2 found no rise in clots. I would still want the prescriber to know about any supplement, but the fear that K2 cancels Eliquis has no mechanism behind it and no data supporting it.
Practical Takeaways
- On warfarin or acenocoumarol: do not start, stop or change a vitamin K2 supplement on your own. Even 10 mcg a day can lower the INR.
- Read labels: check multivitamins, bone formulas and “D3 + K2” products for MK-7 or menaquinone.
- Skip natto on warfarin unless your anticoagulation team says otherwise.
- Keep leafy greens steady, not absent. Wide swings matter more than the amount.
- On Eliquis, Xarelto or another DOAC: K2 has no known way to weaken the drug. Still list it for your prescriber.
- Get help right away for signs of a clot or stroke, such as sudden one-sided weakness, trouble speaking, chest pain, or a swollen, painful leg.
| Blood thinner | Works through vitamin K? | What the evidence says about K2 |
|---|---|---|
| Warfarin, acenocoumarol | Yes | 10 to 45 mcg of MK-7 a day lowered the INR |
| Apixaban (Eliquis) | No | Not studied with K2; no known interaction |
| Rivaroxaban (Xarelto) | No | High-dose K2 added in one trial with no rise in clots |
Related Studies and Research
- Can Vitamin K2 Protect Your Heart? A Large Study Suggests Yes
- Vitamin K2: A Silent Guardian of Heart Health?
- Warfarin and Vascular Calcification: An Unintended Consequence of Vitamin K Blockade
- What Is the MK-4 Form of Vitamin K2 and How Does It Differ From MK-7?
- Do Natto Eaters Have More Vitamin K2 and Denser Bones?
- Do Vitamins D and K Work Better Together for Bones and Heart?
FAQs
Does vitamin K2 thin your blood?
No. Vitamin K2 helps the liver make clotting proteins, so it does not thin blood. In healthy adults and in people on dialysis, MK-7 supplements did not change clotting tests either, so it does not thicken normal blood.
How much vitamin K2 affects warfarin?
In a dose-response study, 10 mcg of MK-7 a day caused a clinically relevant INR drop in at least 40% of people, and 45 mcg a day lowered the average INR by about 40%. The authors noted that 10 mcg is lower than the usual retail dose of 45 mcg.
Does vitamin K2 interfere with Eliquis?
There is no known way for it to. Eliquis blocks factor Xa directly and does not rely on vitamin K. No study has tested K2 with Eliquis, but a trial that added high-dose K2 to rivaroxaban, a drug that works the same way, found no rise in clots.
Is vitamin K2 safe with aspirin or clopidogrel?
Aspirin and clopidogrel block platelets, not vitamin K, so the warfarin interaction does not apply. No study found for this page tested K2 with these drugs, so mention it to your doctor.
Can I take vitamin D3 with K2 if I am on a blood thinner?
Vitamin D3 by itself is not the problem. The K2 in combination products is. On warfarin, choose a D3 product without K2 unless your anticoagulation team approves it.
Bottom Line
Vitamin K2 is not a blood thinner, and it does not thicken normal blood. On warfarin or acenocoumarol, it works directly against the drug, and as little as 10 mcg a day moved the INR in a dose-response study. On Eliquis and other factor Xa blockers, there is no known interaction and the one related trial found no harm. Check every label, and keep your prescriber in the loop.
