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Dietary supplement

Vitamin K2 Ingredients & Drug Interactions

by Klaire Labs

Vitamin K2 label
See full label image
Capsule Category: Vitamin
Most serious interaction: Major
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Vitamin K2 against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Major

Vitamin K2 is a dietary supplement by Klaire Labs with 1 active ingredient. Its ingredients are commonly taken for supporting normal blood clotting, bone health, heart and vascular health.Based on those ingredients, 2 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are Vitamin K2. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Vitamin K2 by Klaire Labs

Ask about any prescription or over-the-counter medication and we check it for interactions with Vitamin K2 by Klaire Labs — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Vitamin K2 by Klaire Labs

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Jul 11, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 1 of its 1 active ingredient.
  • No proprietary blends here — you can verify the dose of every single component.

This product contains one active ingredient: vitamin K2. Vitamin K2 is a fat-soluble vitamin that your body uses to support clotting factors and bone metabolism.

The capsule also includes inactive ingredients — cellulose, a vegetarian capsule shell, L-leucine, and silicon dioxide — which are fillers and binders that help deliver the vitamin.

Does it work?

Strong evidence
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed
Strong

Clinical evidence supports at least one of this product's ingredients for its stated purpose.

Why this rating?
  • The label markets this product for: Support normal blood clotting and bone health.
  • We looked for evidence on: Hemorrhagic disease, Hypoprothrombinemia, Vitamin K-dependent clotting factors deficiency (VKCFD), Warfarin anticoagulation, Osteoporosis, Cardiovascular disease (CVD) — and 3 related terms.
  • The strongest evidence on file: Vitamin K is rated "Effective" for Hemorrhagic disease (Natural Medicines).
  • Also on file: Vitamin K is rated "Effective" for Hypoprothrombinemia, Warfarin anticoagulation, Vitamin K-dependent clotting factors deficiency (VKCFD).
  • Also on file: Vitamin K is rated "Possibly Effective" for Osteoporosis.

Vitamin K2 is effective for treating low clotting factor levels (hypoprothrombinemia and vitamin K-dependent clotting factor deficiency) and for managing certain bleeding disorders. It's also effective for reversing over-anticoagulation from warfarin.

For osteoporosis, the evidence is less certain — vitamin K2 is possibly effective, meaning some evidence suggests a benefit, but it's not yet definitive.

The evidence, ingredient by ingredient Vitamin K

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 1 of the 1 matched ingredient.
  • Pregnancy & breastfeeding safety ratings cover 1 of 1.
  • General safety write-ups exist for 1 of 1.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

When taken by mouth, vitamin K2 is generally well tolerated. The most common side effects are mild gastrointestinal upset — nausea, diarrhea, stomach pain, or abdominal discomfort.

These effects are usually mild to moderate. The safety data says normal dietary amounts are fine for healthy people, but you should check with your doctor before taking supplements, especially if you have any health conditions or take medications.

Side effects, ingredient by ingredient Vitamin K

Meds to double-check

Major interaction found
Known Interaction Concern · database check
Major identified

At least one ingredient has a documented Major-severity interaction. Check your medications for a personalized result.

Why this rating?
  • 1 of the 1 matched ingredient can interact with medications — Vitamin K.
  • The most serious interaction on file is rated Major.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs.
  • For scale: 2 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

If you take warfarin (Coumadin) or phenprocoumon (a blood thinner), do not start this supplement without checking with your pharmacist or doctor first. Vitamin K2 can reduce how well these medications work to prevent clots.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with clinical evidence supporting its stated purpose. Major medication interactions have been identified, and safety information is well characterized.

Vitamin K2 is a straightforward supplement for people who need extra clotting support or who are exploring bone health. If you take warfarin or any other blood thinner, you must talk to your doctor or pharmacist before starting — it can make your anticoagulant less effective and could affect your safety.

Otherwise, it's generally well tolerated in supplement doses.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 1 of 1 active ingredient matched to our full ingredient reviews (monographs). Based on the product label dated Jan 23, 2023.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about Vitamin K2, straight from the product label.

Brand Klaire Labs
Barcode (UPC) 828054001251
Net contents 60 Capsule(s)
Market status On market
Date entered into DSLD Jan 23, 2023
DSLD ID 281386
Product type Vitamin
Supplement form Capsule
Dietary claims / uses Nutrient, All Other
Intended target group(s) Adult (18 - 50 Years), Gluten Free, Dairy Free
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for Vitamin K2 by Klaire Labs, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
1 Capsule(s)
Maximum serving Sizes:
1 Capsule(s)
Servings per container
60
UPC/BARCODE
828054001251
IngredientAmount% DV
Vitamin K250 mcg42%

Other ingredients: Cellulose, Vegetarian Capsule, L-Leucine, Silicon Dioxide

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
Formulation

Free of the following common allergens: milk/casein, eggs, fish, shellfish, tree nuts, peanuts, wheat, gluten, and soybeans. Contains no artificial colors, flavors, or preservatives.

This extract is free of soy protein for maximum tolerance by those sensitive to soy.

Produced under a strict quality management system in compliance with Good Manufacturing Practices (GMPs) and third-party quality certifications.

Suggested/Recommended/Usage/Directions

Suggested use: 1 capsule daily with food or as directed by a healthcare professional.

Formula

This product provides a natural form of vitamin K2 known as menaquinone-7 (MK-7).

Precautions

Do not use if shrinkwrap is broken or missing.

Caution: If you are pregnant, nursing, have a medical condition, or taking prescription drugs, consult your healthcare professional before using this product.

Keep out of reach of children.

All forms of vitamin K may interact with blood thinning medications. If you are taking such medicines, please consult with your physician before taking this product.

Storage

Store in a cool, dry place (59 degrees F-85 degrees F) away from direct light.

FDA Statement of Identity

Dietary Supplement

Brand IP Statement(s)

SFI

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

Vitamin K2 by Klaire Labs label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

Vitamin K2 label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in Vitamin K2 by Klaire Labs

This is the 1 active ingredient this product is made of. Select it to open its full monograph.

Serving size1 Capsule(s) Dosage formCapsule Servings per container60 Amounts shown are per serving.

Vitamin K2

Interacts with
2 drugs
50 mcg per serving Form: Menaquinone-7

Vitamin K is an essential nutrient your body needs for normal blood clotting and to support healthy bones. Most people get enough from food, but suppl...

Vitamin K2 monograph & interactions

Other (inactive) ingredients: Cellulose, Vegetarian Capsule, L-Leucine, Silicon Dioxide. These complete the product’s ingredient list but are not active constituents.

Interaction report

Vitamin K2 by Klaire Labs Drug Interactions

Want to check YOUR meds against Vitamin K2?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

 Go to the checker
2Drugs
2 Major

Ingredients driving the most interactions

Vitamin K2 2

Individual Drug Interactions

The ingredients in Vitamin K2 interact with 2 drugs. Click any drug to see the details.

1 of the 1 ingredient in Vitamin K2 interact with drugs. Each result below shows which ingredient is responsible. Vitamin K2

Each ingredient & the kinds of drugs it affects

For each ingredient in Vitamin K2 with known interactions, here are the types of medications it can affect. Open any type for the detail — or search your exact drug in the checker above.

Vitamin K21 drug type · 2 drugs

Warfarin (Coumadin)

Vitamin K can antagonize and reverse the therapeutic effects of warfarin.
Vitamin K antagonizes the effects of warfarin. Excessive vitamin K intake, either from supplements or from changes in the diet, can reduce the anticoagulant effect of warfarin.

Likelihood Likely Evidence C
Vitamin K2 full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Vitamin K2, from the product label.

Klaire Labs

See all Klaire Labs products
Name
SFI USA
City
Reno
State
NV
ZipCode
89521
Web Address
Klaire.com
Pharmacist Counseling Corner

Vitamin K2 by Klaire Labs: Common Questions

Does Vitamin K2 by Klaire Labs interact with any medications?
Yes. Based on its ingredients, Vitamin K2 has a known interaction with 2 medications, including 2 rated major. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Vitamin K2 contains a single active ingredient, and that one ingredient can interact with many different medications on its own. We check it against each medication and show the mechanism responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
Can I take Vitamin K2 if I'm on warfarin?
No — not without your doctor's or pharmacist's approval. Vitamin K2 can weaken warfarin's blood-thinning effect, which could put you at risk for clots. Your doctor may need to adjust your warfarin dose or monitor you more carefully if you want to use a K2 supplement. Always check first.
What are the side effects of taking Vitamin K2?
The most common side effects when taken by mouth are mild gastrointestinal symptoms: nausea, diarrhea, stomach upset, or abdominal pain. These are usually mild to moderate and are the only effects documented in the data we hold.
Is Vitamin K2 safe to take during pregnancy or while breastfeeding?
The safety data indicates vitamin K2 is likely safe during pregnancy and lactation. But any supplement decision in pregnancy should be made with your doctor or midwife, so talk to them before starting.
What does Vitamin K2 actually do?
Vitamin K2 helps your body produce clotting factors — proteins needed to stop bleeding. It's effective for treating bleeding disorders and for reversing too much blood thinning from warfarin. It may also support bone health, though that evidence is still developing.
Can I just take this for bone health if I don't have a bleeding disorder?
The evidence that vitamin K2 helps osteoporosis is still possibly effective — meaning some evidence suggests a benefit, but we don't have a lot of certainty yet. If bone health is your goal, talk to your doctor about whether it's the right choice for you and whether any medications you take will interact with it.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Not sure if Vitamin K2 is safe with your meds?

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Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

Vitamin K2 label
Go deeper

The Full Monographs Behind Vitamin K2’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Vitamin K

Interacts with 2 drugs

Vitamin K is an essential nutrient your body needs for normal blood clotting and to support healthy bones. Most people get enough from food, but supplements are sometimes used for deficiency...

Read the full Vitamin K monograph →
Sources

Sources & How We Checked

Vitamin K2's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 11 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Vitamin K 11 references
  1. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
  2. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press, 2002.
  3. Crowther MA, Ageno W, Garcia D, et al. Oral vitamin K versus placebo to correct excessive anticoagulation in patients receiving warfarin: a randomized trial. Ann Intern Med. 2009;150(5):293-300. PubMed
  4. Dietary vitamin K guidance: an effective strategy for stable control of oral anticoagulation? Nutr Rev. 2010;68(3):178-81. PubMed
  5. Kim JS, Nafziger AN, Gaedigk A, et al. Effects of oral vitamin K on S- and R-warfarin pharmacokinetics and pharmacodynamics: enhanced safety of warfarin as a CYP2C9 probe. J Clin Pharmacol. 2001 Jul;41(7):715-22. PubMed
  6. Riegert-Johnson, D. L. and Volcheck, G. W. The incidence of anaphylaxis following intravenous phytonadione (vitamin K1): a 5-year retrospective review. Ann.Allergy Asthma Immunol. 2002;89(4):400-406. PubMed
  7. Dezee, K. J., Shimeall, W. T., Douglas, K. M., Shumway, N. M., and O'malley, P. G. Treatment of excessive anticoagulation with phytonadione (vitamin K): a meta-analysis. Arch.Intern.Med. 2-27-2006;166(4):391-397. DOI
  8. Dentali, F., Ageno, W., and Crowther, M. Treatment of coumarin-associated coagulopathy: a systematic review and proposed treatment algorithms. J.Thromb.Haemost. 2006;4(9):1853-1863. PubMed
  9. Caluwé R, Vandecasteele S, Van Vlem B, Vermeer C, De Vriese AS. Vitamin K2 supplementation in haemodialysis patients: a randomized dose-finding study. Nephrol Dial Transplant. 2014;29(7):1385-90.
  10. Huang ZB, Wan SL, Lu YJ, Ning L, Liu C, Fan SW. Does vitamin K2 play a role in the prevention and treatment of osteoporosis for postmenopausal women: a meta-analysis of randomized controlled trials. Osteoporos Int. 2015;26(3):1175-86. PubMed
  11. Hunnali CR, Devi U, Kitchanan S, Sethuraman G. Three Different Regimens for Vitamin K Birth Prophylaxis in Infants Born Preterm: A Randomized Clinical Trial. J Pediatr 2023;255:98-104. PubMed

See these in context on the Vitamin K monograph →

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

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