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Dietary supplement

Vitamin K 2 Ingredients & Drug Interactions

by Signature Supplements

Vitamin K 2 label
See full label image
Capsule Category: Other Combinations
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 K 2 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 K 2 is a dietary supplement by Signature Supplements with 2 active ingredients. Its ingredients are commonly taken for supporting normal blood clotting, bone health, heart and vascular health.Based on those ingredients, 289 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are Nattokinase, 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 K 2 by Signature Supplements

Ask about any prescription or over-the-counter medication and we check it for interactions with Vitamin K 2 by Signature Supplements — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Vitamin K 2 by Signature Supplements

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 2 of its 2 active ingredients.
  • No proprietary blends here — you can verify the dose of every single component.

This product contains two active ingredients: Vitamin K2, which supports blood clotting and bone health, and nattokinase, an enzyme derived from fermented soy. The capsule also contains inactive ingredients (cellulose and diatomaceous earth) as fillers and capsule material.

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: Helps body transport calcium.
  • We looked for evidence on: Osteoporosis, Hemorrhagic disease, Hypoprothrombinemia, Intraventricular hemorrhage, Vitamin K-dependent clotting factors deficiency (VKCFD), Warfarin anticoagulation — and 4 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 vitamin K deficiency, vitamin K-dependent clotting factor deficiency, warfarin anticoagulation reversal, and hemorrhagic disease. It's possibly effective for osteoporosis.

Nattokinase, however, lacks reliable evidence for any of its claimed uses — the data we hold shows insufficient evidence for angina, atherosclerosis, cancer, cardiovascular disease, and chronic fatigue syndrome.

The evidence, ingredient by ingredient Vitamin K Nattokinase

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 2 of the 2 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 2 of 2.
  • General safety write-ups exist for 2 of 2.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Vitamin K2 is generally well tolerated in food and typical supplement amounts; the most common side effects are mild gastrointestinal issues like nausea, diarrhea, and stomach upset. Nattokinase is generally tolerated short-term, but because it thins the blood, it carries a bleeding risk and warrants caution in anyone with bleeding disorders.

Nattokinase safety data during pregnancy is not sufficient — the facts advise against use. Nattokinase should be avoided while breastfeeding due to insufficient safety information.

Side effects, ingredient by ingredient Vitamin K Nattokinase

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?
  • 2 of the 2 matched ingredients can interact with medications — Vitamin K, Nattokinase.
  • The most serious interaction on file is rated Major.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs.
  • For scale: 289 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.

Do not use this product if you take warfarin without medical supervision — Vitamin K2 will directly oppose its effect. Double-check with your pharmacist if you take blood thinners (like aspirin, apixaban, or dabigatran) or blood pressure medications; nattokinase may increase bleeding risk and lower your blood pressure further.

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 may help if you have a clotting disorder or are trying to reverse warfarin — but that last use requires close medical supervision. Nattokinase has no solid evidence behind it and adds real bleeding and blood-pressure risks.

If you take warfarin, any blood thinner, or blood pressure medication, talk to your pharmacist or doctor before starting this product.

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

Assessment coverage: 2 of 2 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Aug 22, 2025.

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 K 2, straight from the product label.

Brand Signature Supplements
Net contents 100 Capsule(s)
Market status On market
Date entered into DSLD Aug 22, 2025
DSLD ID 338979
Product type Other Combinations
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years), Gluten Free, Dairy Free, Sugar 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 K 2 by Signature Supplements, 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:
2 Capsule(s)
Servings per container
50
IngredientAmount% DV
Vitamin K2200 mcg150%
Nattokinase200 mg--

Other ingredients: Cellulose, Diatomaceous

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

No: chemical fillers or binders, artificial coloring, artificial flavor, preservatives, yeast, corn, milk or milk derivatives, lactose, salt, sodium, soy, sugar, gluten, starch or wheat.

From a GMP Facility

Helps body transport calcium Time release

FDA Disclaimer Statement

This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.

FDA Statement of Identity

Dietary Supplement

Suggested/Recommended/Usage/Directions

Directions: For adults, take one (1) to two (2) capsules daily, preferably with a meal.

Precautions

Do not take this product within 2 hours of taking medications or follow the advice of your health care providers. Warning: Pregnant or lactating women should consult a doctor before using any product. Consult doctor before use if you have, or have had, kidney disease, if you are on a magnesium-restricted diet or if you are taking any medications or remedies such as those to treat high blood pressure, heart medications, muscle relaxants or diuretics.

Discontinue use and consult your doctor if any adverse reactions occur, such as gastrointestinal discomfort or low blood pressure.

Not intended for use by persons under the age of 18. Keep out of reach of children.

Storage

Store in a dry place and avoid excessive heat.

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

See for yourself

Vitamin K 2 by Signature Supplements label

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

Vitamin K 2 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 K 2 by Signature Supplements

These are the 2 active ingredients this product is made of. Select any to open its full monograph.

Serving size1 Capsule(s) Dosage formCapsule Servings per container50 Amounts shown are per serving.

Most supplement products combine several ingredients, and a medication can interact with the product through any one of them. Each ingredient below shows whether it has known drug interactions.

Vitamin K2

Interacts with
2 drugs
200 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

Nattokinase

Interacts with
289 drugs
200 mg per serving Form: Natto Extract

Nattokinase is an enzyme from the fermented soybean food natto that may have mild blood-thinning and blood-flow effects. Some small studies hint at be...

Nattokinase monograph & interactions

Other (inactive) ingredients: Cellulose, Diatomaceous. These complete the product’s ingredient list but are not active constituents.

Interaction report

Vitamin K 2 by Signature Supplements Drug Interactions

Want to check YOUR meds against Vitamin K 2?

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
289Drugs
2 Major 287 Moderate

Ingredients driving the most interactions

Nattokinase 289
Vitamin K2 2

Individual Drug Interactions

The ingredients in Vitamin K 2 interact with 289 drugs. Click any drug to see the details.

2 of the 2 ingredients in Vitamin K 2 interact with drugs. Each result below shows which ingredient is responsible. Nattokinase Vitamin K2

Each ingredient & the kinds of drugs it affects

For each ingredient in Vitamin K 2 with known interactions, here are the types of medications they can affect. Open any type for the detail — or search your exact drug in the checker above.

Nattokinase2 drug types · 289 drugs

Anticoagulant/Antiplatelet Drugs

Nattokinase might increase the risk of bleeding when used with anticoagulant/antiplatelet drugs.
Nattokinase has thrombolytic and anticoagulant effects. There is a case report of intracranial hemorrhage in a patient who added nattokinase to aspirin therapy.

Likelihood Possible Evidence D
Antihypertensive Drugs

Theoretically, nattokinase might increase the risk of hypotension when used with antihypertensive drugs.
Some clinical research suggests that nattokinase may reduce systolic and diastolic blood pressure.

Likelihood Possible Evidence D
Nattokinase full monograph & interactions

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 K 2, from the product label.

Signature Supplements

See all Signature Supplements products
Name
Signature Supplements
Street Address
P.O. Box 1112
City
San Clemente
State
CA
Web Address
yoursignaturesupplements.com
Pharmacist Counseling Corner

Vitamin K 2 by Signature Supplements: Common Questions

Does Vitamin K 2 by Signature Supplements interact with any medications?
Yes. Based on its ingredients, Vitamin K 2 has a known interaction with 289 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 K 2 contains 2 active ingredients, and an interaction can come from any of them. We check every ingredient, combine the results into one list per medication, and show which ingredient and mechanism is 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 this with warfarin?
No, not without your doctor's close supervision. Vitamin K2 directly antagonizes warfarin's blood-thinning effect and can make it ineffective. This is a Major-severity interaction. Talk to your prescriber before adding this product.
What are the side effects of Vitamin K2?
Orally, it's generally well tolerated. The most common side effects are mild gastrointestinal ones — nausea, diarrhea, and stomach upset. Serious reactions are rare.
Can I take this while pregnant?
Vitamin K2 is likely safe in pregnancy. Nattokinase, however, does not have enough safety data — the facts advise against it. Talk to your doctor or pharmacist for personalized advice.
Can I take this while breastfeeding?
Data on nattokinase safety while breastfeeding is not available, and the facts advise against use. Vitamin K2 safety during breastfeeding is not detailed in our data — ask your pharmacist.
What does nattokinase actually do?
Nattokinase is an enzyme from fermented soy. We don't have reliable evidence it works for any condition — claims about angina, heart disease, atherosclerosis, cancer, and fatigue all lack sufficient proof in our data.
Is this safe if I take blood pressure medication?
Not without checking first. Nattokinase may lower your blood pressure further, increasing the risk of dizziness or fainting. Ask your pharmacist to review your specific medication before starting.

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

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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 K 2 label
Go deeper

The Full Monographs Behind Vitamin K 2’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 → Herb & supplement monograph

Nattokinase

Interacts with 289 drugs

Nattokinase is an enzyme from the fermented soybean food natto that may have mild blood-thinning and blood-flow effects. Some small studies hint at benefits for blood pressure and circulatio...

Read the full Nattokinase monograph →
Sources

Sources & How We Checked

Vitamin K 2'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 20 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 →

Nattokinase 9 references
  1. Suzuki Y, Kondo K, Matsumoto Y, et al. Dietary supplementation of fermented soybean, natto, suppresses intimal thickening and modulates the lysis of mural thrombi after endothelial injury in rat femoral artery. Life Sci 2003;73:1289-98.. PubMed
  2. Sumi H, Hamada H, Nakanishi K, Hiratani H. Enchancement of fibrinolytic activity in plasma by oral administration of nattokinase. Acta Haematol 1990;84:139-43.
  3. Chang, Y. Y., Liu, J. S., Lai, S. L., Wu, H. S., and Lan, M. Y. Cerebellar hemorrhage provoked by combined use of nattokinase and aspirin in a patient with cerebral microbleeds. Intern Med 2008;47(5):467-469. PubMed
  4. Kim, J. Y., Gum, S. N., Paik, J. K., Lim, H. H., Kim, K. C., Ogasawara, K., Inoue, K., Park, S., Jang, Y., and Lee, J. H. Effects of nattokinase on blood pressure: a randomized, controlled trial. Hypertens.Res 2008;31(8):1583-1588. PubMed
  5. <p>Maruyama M, Sumi H (eds): Effect of natto diet on blood pressure, in Basic and Clinical Aspects of Japanese Traditional Food Natto II. Japan Technology Transfer Association (JTTAS), 1998, pp 1–3.</p>
  6. Kurosawa Y, Nirengi S, Homma T, et al. A single-dose of oral nattokinase potentiates thrombolysis and anti-coagulation profiles. Sci Rep 2015;5:11601. PubMed
  7. Ramachandran L, Aqeel A, Jafri A, Sidhu Y, Mohamed Djirdeh T. Nattokinase-associated hemoperitoneum in an elderly woman. Cureus 2021;13(12):e20074. PubMed
  8. Awatani-Yoshidome K, Hashimoto T, Satoh T. Anaphylaxis from nattokinase in a patient with fermented soybean (natto) allergy. Allergol Int 2022;71(1):153-4. PubMed
  9. Suzuki K, Nakamura M, Sato N, Futamura K, Matsunaga K, Yagami A. Nattokinase, a subtilisin family serine protease, is a novel allergen contained in the traditional Japanese fermented food natto. Allergol Int 2022.

See these in context on the Nattokinase 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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