Major interaction on record — check this product against your medications before combining. Check your meds →
Dietary supplement

Natto-Serra (Nattokinase-Serrapeptase) Ingredients & Drug Interactions

by Doctor's Best

Natto-Serra (Nattokinase-Serrapeptase) 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 Natto-Serra (Nattokinase-Serrapeptase) 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

Natto-Serra (Nattokinase-Serrapeptase) is a dietary supplement by Doctor's Best with 3 active ingredients. Its ingredients are commonly taken for inflammation and swelling, sinus and respiratory congestion, pain after surgery or injury.Based on those ingredients, 377 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are Nattokinase, Calcium, Serrapeptase. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Natto-Serra (Nattokinase-Serrapeptase) by Doctor's Best

Ask about any prescription or over-the-counter medication and we check it for interactions with Natto-Serra (Nattokinase-Serrapeptase) by Doctor's Best — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
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HelloPharmacist Scorecard of Natto-Serra (Nattokinase-Serrapeptase) by Doctor's Best

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 27, 2026

What’s inside

Low disclosure
Ingredient Transparency · database check
Low

Most active ingredients don't disclose an individual amount — you can't tell how much of each you're getting.

Why this rating?
  • The label discloses an exact amount for 1 of its 3 active ingredients.

Natto-Serra contains three active ingredients: serrapeptase (a protein-digesting enzyme from bacteria), nattokinase (a clot-dissolving enzyme from fermented soybeans), and calcium (a mineral). Together they're designed to support blood flow and circulation.

The product also contains several inactive ingredients—maltodextrin, tricalcium phosphate, calcium stearate, medium chain triglyceride, hypromellose, gellan gum, and purified water—which are fillers, binders, and capsule materials.

Does it work?

Moderate 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
Moderate

Some clinical evidence supports this product's ingredients for its stated purpose, but it isn't conclusive.

Why this rating?
  • The label markets this product for: support circulatory and immune system.
  • We looked for evidence on: Angina, Atherosclerosis, Cardiovascular disease (CVD), Dyslipidemia, Heart failure, Hyperlipidemia — and 4 related terms.
  • The strongest evidence on file: Calcium is rated "Possibly Effective" for Pregnancy-induced hypertension (Natural Medicines).
  • Also on file: Calcium is rated "Ineffective" for Cardiovascular disease (CVD), Myocardial infarction (MI).
  • Also on file: Calcium is rated "Insufficient Reliable Evidence To Rate" for Atherosclerosis, Heart failure, Dyslipidemia, Stroke.

The evidence for these ingredients is limited. Nattokinase and serrapeptase both carry ratings of insufficient evidence for their claimed uses—heart health, atherosclerosis, asthma, back pain, and bone health have not been reliably established in studies we hold data for.

Calcium, on the other hand, is rated effective for kidney disease support, upset stomach, low blood calcium, and high potassium levels, and likely effective for osteoporosis. If you're considering this product for circulation or cardiovascular reasons, the evidence doesn't yet support those claims—talk with your doctor about what the research actually shows for your particular concern.

The evidence, ingredient by ingredient Serrapeptase Calcium 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 3 of the 3 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 3 of 3.
  • General safety write-ups exist for 3 of 3.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Serrapeptase is generally well tolerated short-term, but long-term safety hasn't been well studied; the most common side effects are stomach pain, nausea, and upset stomach, though these occur at rates similar to placebo. A rare serious side effect (bullous pemphigoid, a blistering skin condition) has been reported.

Nattokinase is also generally tolerated short-term, though it carries a blood-thinning effect and rare cases of bleeding have been reported—including one brain hemorrhage when combined with aspirin. Calcium is well tolerated at recommended doses, with common mild side effects like constipation or stomach upset; high doses raise concerns about kidney stones and possibly prostate cancer risk.

Neither serrapeptase nor nattokinase has adequate safety data in pregnancy or while breastfeeding—both should be avoided in these periods. Calcium is likely safe in pregnancy at recommended amounts and can support your needs while breastfeeding, but check with your provider.

Side effects, ingredient by ingredient Serrapeptase Calcium 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?
  • 3 of the 3 matched ingredients can interact with medications — Calcium, Nattokinase, Serrapeptase.
  • The most serious interaction on file is rated Major.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; heart-rhythm medications; lithium.
  • For scale: 377 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.

Before taking Natto-Serra, check with your pharmacist if you take any HIV integrase inhibitors (dolutegravir, elvitegravir, raltegravir), heart medications like diltiazem or sotalol, thyroid medication (levothyroxine), or antibiotics like ceftriaxone—calcium can interfere with how well they work. If you take blood thinners (anticoagulants) or antiplatelet drugs like aspirin, warfarin, or clopidogrel, nattokinase and serrapeptase may increase your bleeding risk.

Both of these interactions are documented in our data; discuss any of these medications with your own doctor or pharmacist before starting.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFormula with limited ingredient disclosure with some supporting evidence for its stated purpose. Major medication interactions have been identified, and safety information is well characterized.

Natto-Serra is designed for circulation support, but the evidence for nattokinase and serrapeptase for that purpose is not yet established. The main concern is its calcium content, which can significantly interfere with HIV medications, heart drugs, thyroid medication, and other prescriptions—and both nattokinase and serrapeptase may increase bleeding risk if you take blood thinners.

If you're on any regular medication, run it through the interaction checker on this page or ask your own pharmacist before starting. Pregnant or breastfeeding?

Skip this product and talk with your doctor.

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

Assessment coverage: 3 of 3 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Jan 24, 2024.

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 Natto-Serra (Nattokinase-Serrapeptase), straight from the product label.

Brand Doctor's Best
Barcode (UPC) 753950002944
Net contents 90 Veggie Cap(s)
Market status On market
Date entered into DSLD Jan 24, 2024
DSLD ID 302694
Product type Other Combinations
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Vegan, Vegetarian, Adult (18 - 50 Years), Women (not pregnant or lactating), 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 Natto-Serra (Nattokinase-Serrapeptase) by Doctor's Best, 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 Veggie Capsule(s)
Maximum serving Sizes:
1 Veggie Capsule(s)
Servings per container
90
UPC/BARCODE
753950002944
IngredientAmount% DV
Serrapeptase0 NP--
Calcium29 mg2%
Nattokinase0 NP--

Other ingredients: Maltodextrin, Tricalcium Phosphate, Calcium Stearate, Medium Chain Triglyceride, Hypromellose, Gellan Gum, Water, Purified

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.
Formula

Doctor’s Best Natto-Serra (Nattokinase-Serrapeptase) is a combination of two natural enzymes that have been used as dietary supplements for decades. Serrapeptase (serratio-peptidase) is a protein-digesting enzyme isolated from the friendly bacterium Serratia E-15 discovered in the Japanese silkworm. Nattokinase also digests protein and is derived from “natto”, a fermented soy food popular in Japan for centuries. The serrapeptase is formulated with Serrateric, a superior alternative to enteric coating that protects the enzyme until it reaches the intestine for optimal absorption.

Formulation

Helps support the circulatory system Helps support the immune system

Helps Support the Circulatory and Immune System

Non-GMO

Vegan

This nattokinase is free of vitamin K.

FDA Disclaimer Statement

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

Brand IP Statement(s)

Serrateric is a trademark of Deerland Enzymes, Inc.

Doctor's Best Science-Based Nutrition

FDA Statement of Identity

Dietary Supplement

Precautions

Contains soy

Warning: Not recommended for individuals who are pregnant, nursing, allergic to soy, or have poor digestion. Consult a physician before use if taking blood thinners.

Warning: Not recommended for individuals who are pregnant, nursing, allergic to soy, or have poor digestion.

Stop taking if you experience nausea, vomiting or stomach upset.

Keep out of reach of children

Suggested/Recommended/Usage/Directions

Suggested Adult Use: Take 1 capsule daily without food, or as recommended by a nutritionally informed physician.

Storage

Store in a cool dry place.

Seals/Symbols

Vegan

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

See for yourself

Natto-Serra (Nattokinase-Serrapeptase) by Doctor's Best label

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

Natto-Serra (Nattokinase-Serrapeptase) 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 Natto-Serra (Nattokinase-Serrapeptase) by Doctor's Best

These are the 3 active ingredients this product is made of. Select any to open its full monograph.

Serving size1 Veggie Capsule(s) Dosage formCapsule Servings per container90 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.

Serrapeptase

Interacts with
122 drugs
0 NP per serving Form: Serratia sp.

Serrapeptase is an enzyme marketed to reduce inflammation, swelling, pain, and mucus, but the human evidence is limited and mostly low quality. If you...

Serrapeptase monograph & interactions

Calcium

Interacts with
168 drugs
29 mg per serving Form: Calcium Stearate, Tricalcium Phosphate

Calcium is an essential mineral your body needs for strong bones, nerve signaling, and muscle function, and supplements can help fill gaps when diet f...

Calcium monograph & interactions

Nattokinase

Interacts with
289 drugs
0 NP per serving Form: Fibrinase

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: Maltodextrin, Tricalcium Phosphate, Calcium Stearate, Medium Chain Triglyceride, Hypromellose, Gellan Gum, Water, Purified. These complete the product’s ingredient list but are not active constituents.

Interaction report

Natto-Serra (Nattokinase-Serrapeptase) by Doctor's Best Drug Interactions

Want to check YOUR meds against Natto-Serra (Nattokinase-Serrapeptase)?

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
377Drugs
7 Major 368 Moderate 2 Minor

Ingredients driving the most interactions

Nattokinase 289
Calcium 168
Serrapeptase 122

Individual Drug Interactions

The ingredients in Natto-Serra (Nattokinase-Serrapeptase) interact with 377 drugs. Click any drug to see the details.

3 of the 3 ingredients in Natto-Serra (Nattokinase-Serrapeptase) interact with drugs. Each result below shows which ingredient is responsible. Nattokinase Calcium Serrapeptase

Each ingredient & the kinds of drugs it affects

For each ingredient in Natto-Serra (Nattokinase-Serrapeptase) 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

Calcium18 drug types · 168 drugs

Ceftriaxone (Rocephin)

Co-administration of intravenous calcium and ceftriaxone can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys.
Avoid administering intravenous calcium in any form, such as parenteral nutrition or Lactated Ringers, within 48 hours of intravenous ceftriaxone. Case reports in neonates show that administering intravenous ceftriaxone and calcium can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys. In several cases, neonates have died as a result of this interaction. So far there are no reports in adults; however, there is still concern that this interaction might occur in adults.

Likelihood Probable Evidence D
Dolutegravir (Tivicay)

Calcium seems to reduce levels of dolutegravir.
Advise patients to take dolutegravir either 2 hours before or 6 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium carbonate 1200 mg concomitantly with dolutegravir 50 mg reduces plasma levels of dolutegravir by almost 40%. Calcium appears to decrease levels of dolutegravir through chelation.

Likelihood Probable Evidence B
Elvitegravir (Vitekta)

Calcium seems to reduce levels of elvitegravir.
Advise patients to take elvitegravir either 2 hours before or 2 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium along with elvitegravir can reduce blood levels of elvitegravir through chelation.

Likelihood Probable Evidence B
Aluminum

Calcium citrate might increase aluminum absorption and toxicity. Other types of calcium do not increase aluminum absorption.
Calcium citrate can increase the absorption of aluminum when taken with aluminum hydroxide. The increase in aluminum levels may become toxic, particularly in individuals with kidney disease. However, the effect of calcium citrate on aluminum absorption is due to the citrate anion rather than calcium cation. Calcium acetate does not appear to increase aluminum absorption.

Likelihood Possible Evidence B
Bictegravir/Emtricitabine/Tenofovir Alafenamide (Biktarvy)

Calcium might decrease levels of bictegravir/emtricitabine/tenofovir alafenamide by reducing its absorption when taken in a fasting state.
Advise patients that bictegravir/emtricitabine/tenofovir alafenamide and calcium can be taken together if taken with food. However, if taken on an empty stomach, bictegravir/emtricitabine/tenofovir alafenamide should not be taken with, or 2 hours after, calcium containing products.

Likelihood Probable Evidence D
Bisphosphonates

Calcium reduces the absorption of bisphosphonates.
Advise patients to take bisphosphonates at least 30 minutes before calcium, but preferably at a different time of day. Calcium supplements decrease absorption of bisphosphonates.

Likelihood Probable Evidence C
Calcipotriene (Dovonex)

Taking calcipotriene with calcium might increase the risk for hypercalcemia.
Calcipotriene is a vitamin D analog used topically for psoriasis. It can be absorbed in sufficient amounts to cause systemic effects, including hypercalcemia. Theoretically, combining calcipotriene with calcium supplements might increase the risk of hypercalcemia.

Likelihood Possible Evidence B
Digoxin (Lanoxin)

Using intravenous calcium with digoxin might increase the risk of fatal cardiac arrhythmias.
Hypercalcemia increases the risk of fatal cardiac arrhythmias with digoxin. However, one retrospective analysis of clinical data suggests that intravenous calcium does not increase the risk of dysrhythmias or mortality in patients receiving digoxin.

Likelihood Possible Evidence B
Diltiazem (Cardizem, Others)

Theoretically, calcium may reduce the therapeutic effects of diltiazem.
Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation. Theoretically, calcium might increase this risk of hypercalcemia and reduce the effectiveness of diltiazem.

Likelihood Probable Evidence D
Levothyroxine (Synthroid, Others)

Calcium seems to reduce the absorption and effectiveness of levothyroxine.
Advise patients to take levothyroxine and calcium supplements at least 4 hours apart. Calcium reduces levothyroxine absorption, probably by forming insoluble complexes. Calcium carbonate supplements reduce effectiveness of levothyroxine in patients with hypothyroidism.

Likelihood Probable Evidence B
Lithium

Theoretically, concomitant use of calcium and lithium may increase this risk of hypercalcemia.
Clinical research suggests that long-term use of lithium may cause hypercalcemia in 10% to 60% of patients. Theoretically, concomitant use of lithium and calcium supplements may further increase this risk.

Likelihood Possible Evidence B
Quinolone Antibiotics

Calcium seems to reduce the absorption of quinolone antibiotics.
Advise patients to take oral quinolones at least 2 hours before or 4-6 hours after calcium supplements or calcium-fortified foods. Taking calcium at the same time as oral quinolones can reduce quinolone absorption. Calcium binds to quinolones in the gut.

Likelihood Probable Evidence B
Raltegravir (Isentress)

Calcium may reduce levels of raltegravir.
Pharmacokinetic research shows that taking a single dose of calcium carbonate 3000 mg along with raltegravir 400 mg twice daily modestly decreases the mean area under the curve of raltegravir, but the decrease does not necessitate a dose adjustment of raltegravir. However, a case of elevated HIV-1 RNA levels and documented resistance to raltegravir has been reported for a patient taking calcium carbonate 1 gram three times daily plus vitamin D3 (cholecalciferol) 400 IU three times daily in combination with raltegravir 400 mg twice daily for 11 months. It is thought that calcium reduced raltegravir levels by chelation, leading to treatment failure.

Likelihood Possible Evidence B
Sotalol (Betapace)

Calcium seems to reduce the absorption of sotalol.
Advise patients to separate doses by at least 2 hours before or 4-6 hours after calcium. Calcium appears to reduce the absorption of sotalol, probably by forming insoluble complexes.

Likelihood Possible Evidence B
Tetracycline Antibiotics

Calcium seems to reduce the absorption of tetracycline antibiotics.
Advise patients to take oral tetracyclines at least 2 hours before, or 4-6 hours after calcium supplements. Taking calcium at the same time as oral tetracyclines can reduce tetracycline absorption. Calcium binds to tetracyclines in the gut.

Likelihood Probable Evidence C
Thiazide Diuretics

Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.
Thiazides reduce calcium excretion by the kidneys. Using thiazides along with moderately large amounts of calcium carbonate increases the risk of milk-alkali syndrome (hypercalcemia, metabolic alkalosis, renal failure). Patients may need to have their serum calcium levels and/or parathyroid function monitored regularly.

Likelihood Probable Evidence C
Verapamil (Calan, Others)

Theoretically, calcium may reduce the therapeutic effects of verapamil.
Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation. Theoretically, use of calcium supplements may increase this risk of hypercalcemia and reduce the effectiveness of verapamil.

Likelihood Probable Evidence D
Calcium Channel Blockers

Intravenous calcium may decrease the effects of calcium channel blockers; oral calcium is unlikely to have this effect.
Intravenous calcium is used to decrease the effects of calcium channel blockers in the management of overdose. Intravenous calcium gluconate has been used before intravenous verapamil (Isoptin) to prevent or reduce the hypotensive effects without affecting the antiarrhythmic effects. But there is no evidence that dietary or supplemental calcium when taken orally interacts with calcium channel blockers.

Likelihood Unlikely Evidence D
Calcium full monograph & interactions

Serrapeptase1 drug type · 122 drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, taking serrapeptase with drugs that have antiplatelet or anticoagulant effects might increase the risk of bruising and bleeding.
In vitro research shows that serrapeptase has fibrinolytic activity.

Likelihood Possible Evidence D
Serrapeptase full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Natto-Serra (Nattokinase-Serrapeptase), from the product label.

Doctor's Best

See all Doctor's Best products
Name
Doctor's Best, Inc.
City
Tustin
State
California
ZipCode
92780
Phone Number
(800) 777-2474
Web Address
www.drbvitamins.com
Pharmacist Counseling Corner

Natto-Serra (Nattokinase-Serrapeptase) by Doctor's Best: Common Questions

Does Natto-Serra (Nattokinase-Serrapeptase) by Doctor's Best interact with any medications?
Yes. Based on its ingredients, Natto-Serra (Nattokinase-Serrapeptase) has a known interaction with 377 medications, including 7 rated major. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Natto-Serra (Nattokinase-Serrapeptase) contains 3 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.
What exactly is nattokinase?
Nattokinase is an enzyme that comes from natto—fermented soybeans—and has blood-thinning and clot-dissolving properties. It's used in some supplements for heart and circulation support, though strong evidence for those uses is still limited.
What is serrapeptase and what's it supposed to do?
Serrapeptase is a protein-digesting enzyme originally found in bacteria. It's added to supplements for asthma, back pain, atherosclerosis, and bone health, but the evidence we hold rates all of these uses as having insufficient reliable evidence.
Can I take this while pregnant or breastfeeding?
No—the safety data for both nattokinase and serrapeptase advises against use during pregnancy and breastfeeding because there isn't enough information. Calcium in the product is safe at recommended amounts during both periods, but because of the other two ingredients, you should skip this product and talk with your doctor about safer alternatives.
What side effects does serrapeptase cause?
Most common are stomach pain, nausea, and upset stomach, though these happen at the same rate as placebo in studies. A rare serious side effect (bullous pemphigoid, a blistering skin condition) has been reported. Long-term safety hasn't been well studied.
Why does calcium interact with so many medications?
Calcium forms insoluble complexes with certain drugs, which prevents your body from absorbing them properly, making them less effective. It also lowers levels of HIV medications through a process called chelation. That's why timing matters—your pharmacist can help you space doses correctly if you need to take this product alongside other medications.
Is this safe if I take aspirin?
Not without talking to your doctor first. Both nattokinase and serrapeptase in this product can thin the blood, and there's a documented case of brain hemorrhage when nattokinase was combined with low-dose aspirin. Your own pharmacist or doctor needs to weigh the risk for you personally.

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.

Natto-Serra (Nattokinase-Serrapeptase) label
Go deeper

The Full Monographs Behind Natto-Serra (Nattokinase-Serrapeptase)’s Ingredients

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

Herb & supplement monograph

Serrapeptase

Interacts with 122 drugs

Serrapeptase is an enzyme marketed to reduce inflammation, swelling, pain, and mucus, but the human evidence is limited and mostly low quality. If you want to try it, choose an enteric-coate...

Read the full Serrapeptase monograph → Herb & supplement monograph

Calcium

Interacts with 168 drugs

Calcium is an essential mineral your body needs for strong bones, nerve signaling, and muscle function, and supplements can help fill gaps when diet falls short. Most people do best getting...

Read the full Calcium 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

Natto-Serra (Nattokinase-Serrapeptase)'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 73 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.

Serrapeptase 2 references
  1. Tachibana M, Mizukoshi O, Harada Y, et al. A multi-centre, double-blind study of serrapeptase versus placebo in post-antrotomy buccal swelling. Pharmatherapeutica 1984;3:526-30..
  2. Mazzone A, Catalani M, Costanzo M, et al. Evaluation of Serratia peptidase in acute or chronic inflammation of otorhinolaryngology pathology: a multicentre, double-blind, randomized trial versus placebo. J Int Med Res 1990;18:379-88.. PubMed

See these in context on the Serrapeptase monograph →

Calcium 62 references
  1. Shils M, Olson A, Shike M. Modern Nutrition in Health and Disease. 8th ed. Philadelphia, PA: Lea and Febiger, 1994.
  2. Hernandez-Avila M, Gonzalez-Cossio T, Hernandez-Avila JE, et al. Dietary calcium supplements to lower blood lead levels in lactating women: a randomized placebo-controlled trial. Epidemiology 2003;14:206-12.. PubMed
  3. Thys-Jacobs S, Ceccarelli S, Bierman A, et al. Calcium supplementation in premenstrual syndrome: a randomized crossover trial. J Gen Intern Med 1989;4:183-9. PubMed
  4. Maton PN, Burton ME. Antacids revisited: a review of their clinical pharmacology and recommended therapeutic use. Drugs 1999;57:855-70.
  5. Clemens JD, Feinstein AR. Calcium carbonate and constipation: a historical review of medical mythopoeia. Gastroenterology 1977;72:957-61. DOI
  6. Saunders D, Sillery J, Chapman R. Effect of calcium carbonate and aluminum hydroxide on human intestinal function. Dig Dis Sci 1988;33:409-13. PubMed
  7. Friedman PA, Bushinsky DA. Diuretic effects on calcium metabolism. Semin Nephrol 1999;19:551-6.
  8. Koo WK, Walters JC, Esterlitz J, et al. Maternal calcium supplementation and fetal bone mineralization. Obstet Gynecol 1999;94:577-82. DOI
  9. Raman L, Rajalakshmi K, Krishnamachari KAVR, et al. Effect of calcium supplementation to undernourished mothers during pregnancy on the bone density of the neonates. Am J Clin Nutr 1978; 31:466-9. DOI
  10. Murry JJ, Healy MD. Drug-mineral interactions: a new responsibility for the hospital dietician. J Am Diet Assoc 1991;91:66-73.
  11. Chan JM, Giovannucci E, Andersson SO, et al. Dairy products, calcium, phosphorous, vitamin D, and risk of prostate cancer. Cancer Causes Control 1998;9:559-66.
  12. Butner LE, Fulco PP, Feldman G, et al. Calcium carbonate-induced hypothyroidism. Ann Intern Med 2000:132:595. PubMed
  13. Schneyer CR. Calcium carbonate and reduction of levothyroxine efficacy. JAMA 1998;279:750. PubMed
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See these in context on the Calcium monograph →

Nattokinase 9 references
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See these in context on the Nattokinase monograph →

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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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