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Dietary supplement

K-2 with Nattokinase Ingredients & Drug Interactions

by Swanson

K-2 with Nattokinase label
See full label image
Softgel 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 K-2 with Nattokinase 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

K-2 with Nattokinase is a dietary supplement by Swanson with 2 active ingredients. Its ingredients are commonly taken for heart and circulatory health, blood clot prevention, high blood pressure.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 K-2. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against K-2 with Nattokinase by Swanson

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

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HelloPharmacist Scorecard of K-2 with Nattokinase by Swanson

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 Aug 13, 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 2 active ingredients. Nattokinase is an enzyme derived from natto (fermented soybeans) that has blood-thinning and clot-dissolving properties.

Vitamin K-2 (menaquinone) is a fat-soluble vitamin that plays a key role in blood clotting and bone metabolism. The inactive ingredients are sunflower oil, gelatin, glycerin, purified water, beeswax, maltodextrin, carob, and dibasic calcium phosphate—these are fillers and capsule materials.

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: Heart and circulatory health with blood clotting support.
  • We looked for evidence on: Angina, Atherosclerosis, Cardiovascular disease (CVD), Hemorrhagic disease, Hyperlipidemia, Hypertension — 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.
  • Also on file: Vitamin K is rated "Insufficient Reliable Evidence To Rate" for Cardiovascular disease (CVD), Stroke.

The evidence we hold on nattokinase doesn't support claims for angina, atherosclerosis, cancer, cardiovascular disease, or chronic fatigue syndrome—the data shows insufficient reliable evidence for any of these uses. Vitamin K-2 is effective for correcting vitamin K deficiency and supporting the blood's clotting proteins, and it's possibly effective for osteoporosis.

If you're interested in this product for cardiovascular or bone health, talk it over with your doctor or pharmacist so they can recommend an approach backed by evidence for your situation.

The evidence, ingredient by ingredient Nattokinase 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 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.

Nattokinase is generally tolerated in the short term, but its blood-thinning effect means it isn't right for anyone with bleeding disorders or high bleeding risk. It's not safe in pregnancy—there isn't enough data to know.

Breastfeeding safety is also unknown, so it should be avoided while nursing. Vitamin K-2 is generally safe in the amounts found in food and most supplements for healthy adults, though it can cause mild stomach upset, nausea, or diarrhea.

Both ingredients carry rare risk of allergic reaction, and nattokinase has been linked to rare bleeding events, including one case of brain hemorrhage when combined with aspirin.

Side effects, ingredient by ingredient Nattokinase 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?
  • 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.

Stop and check with your doctor or pharmacist before taking this product if you use warfarin (Coumadin)—vitamin K-2 directly reduces its effectiveness. Also verify with your provider if you take any blood thinner or antiplatelet drug (like apixaban, rivaroxaban, clopidogrel, or aspirin), any blood pressure medication, or if you have a history of bleeding.

Nattokinase's blood-thinning effects can compound these risks.

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.

This product is designed for people interested in cardiovascular support through blood-thinning and bone health, but the evidence for nattokinase in these areas is sparse. If you take warfarin, any blood thinner, aspirin, or blood pressure medicine, you need to check with your doctor or pharmacist before starting—the interaction risks are real.

Pregnant or breastfeeding women should avoid it. For anyone else without bleeding risk or medication conflicts, discuss it with your own healthcare provider first.

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 Feb 25, 2019.

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 K-2 with Nattokinase, straight from the product label.

Brand Swanson
Barcode (UPC) 087614028194
Net contents 30 Softgel(s)
Market status On market
Date entered into DSLD Feb 25, 2019
DSLD ID 190970
Product type Other Combinations
Supplement form Softgel Capsule
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years)
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 K-2 with Nattokinase by Swanson, 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 Softgel(s)
Maximum serving Sizes:
1 Softgel(s)
UPC/BARCODE
087614028194
IngredientAmount% DV
Nattokinase100 mg--
Vitamin K-250 mcg--

Other ingredients: Sunflower Oil, Gelatin, Glycerin, purified (deionized) Water, Beeswax, Maltodextrin, Carob, Dibasic Calcium Phosphate

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.
Suggested/Recommended/Usage/Directions

Suggested use: As a dietary supplement, take one softgel per day with water.

Precautions

Warning: For adults only.

Do not use if you have a blood coagulation disorder and/or if you are taking any drug that affects blood coagulation such as prescription vitamin k, heparin or warfarin (coumadin). Consult your healthcare provider before use if you are taking prescription medication, have a medical condition of if you are pregnant or nursing.

Keep out of reach of children.

Do not use if seal is broken.

Contains sulfites and soy.

Storage

Store in a cool, dry place. Do not refrigerate.

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.

General

SWU819 Rev 0 06 06 18

Formula

Natural Vitamin K-2

with Nattokinase

Contains sulfites and soy.

General Statements

Bone and Cardiovascular Health

FDA Statement of Identity

Dietary Supplement

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

See for yourself

K-2 with Nattokinase by Swanson label

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

K-2 with Nattokinase 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 K-2 with Nattokinase by Swanson

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

Serving size1 Softgel(s) Dosage formSoftgel Capsule 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.

Nattokinase

Interacts with
289 drugs
100 mg per serving

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

Vitamin K-2

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 K-2 monograph & interactions

Other (inactive) ingredients: Sunflower Oil, Gelatin, Glycerin, Purified (deionized) Water, Beeswax, Maltodextrin, Carob, Dibasic Calcium Phosphate. These complete the product’s ingredient list but are not active constituents.

Interaction report

K-2 with Nattokinase by Swanson Drug Interactions

Want to check YOUR meds against K-2 with Nattokinase?

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 K-2 2

Individual Drug Interactions

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

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

Each ingredient & the kinds of drugs it affects

For each ingredient in K-2 with Nattokinase 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 K-21 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 K-2 full monograph & interactions
The maker

Brand information

Manufacturer and brand details for K-2 with Nattokinase, from the product label.

Swanson

See all Swanson products
Name
Swanson Health Products
City
Fargo
State
ND
ZipCode
58104
Phone Number
1-800-437-4148
Web Address
www.swanson.com
Pharmacist Counseling Corner

K-2 with Nattokinase by Swanson: Common Questions

Does K-2 with Nattokinase by Swanson interact with any medications?
Yes. Based on its ingredients, K-2 with Nattokinase 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?
K-2 with Nattokinase 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 if I'm on aspirin or another blood thinner?
Not without talking to your doctor first. Nattokinase thins the blood, and there's a documented case of brain hemorrhage when nattokinase was added to aspirin. If you're on any blood thinner—prescription or over-the-counter—your provider needs to weigh the risks and benefits for you personally.
What if I take warfarin?
Do not start this product without checking with your doctor. Vitamin K-2 in this supplement directly opposes warfarin's blood-thinning effect, which could reduce how well your warfarin works and put you at clot risk. Your doctor may need to adjust your warfarin dose or recommend a different supplement.
Is it safe during pregnancy?
No. The data shows nattokinase isn't safe in pregnancy, and there isn't enough information on vitamin K-2 safety while pregnant either. If you're planning to conceive, pregnant, or breastfeeding, talk with your doctor before using this product.
What side effects might I experience?
Vitamin K-2 can cause mild stomach upset, nausea, or diarrhea. Nattokinase is generally tolerated but carries rare risk of bleeding or allergic reactions (throat swelling or anaphylaxis) in people sensitive to fermented soy products. Stop and seek immediate care if you notice unusual bruising, bleeding, or allergy symptoms.
Does this actually help with heart health or bone health?
The evidence on nattokinase for cardiovascular or bone health is insufficient—we don't have reliable data supporting those claims. Vitamin K-2 is possibly effective for osteoporosis, but for heart health there's no established evidence. Your doctor can recommend options with stronger evidence for your situation.

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.

K-2 with Nattokinase label
Go deeper

The Full Monographs Behind K-2 with Nattokinase’s Ingredients

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

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 → 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

K-2 with Nattokinase'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.

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 →

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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