Is it safe to take nattokinase every day?

December 25, 2025 •

3 min read

For centuries, the Japanese have consumed natto, the fermented soybean food from which nattokinase is derived, with claims of health benefits. This long history of use raises the question of whether daily consumption of the isolated enzyme is equally safe and beneficial for modern consumers.

Quick Summary

Nattokinase is generally considered safe for daily use by most healthy adults at recommended doses for up to three years. However, significant risks exist for individuals on blood-thinning medication or with bleeding disorders due to an increased risk of excessive bleeding.

Key Points

Generally Safe: Daily nattokinase at recommended doses is generally considered safe for most healthy adults, with studies supporting use for up to three years.
Significant Drug Interactions: The most significant risk is interaction with blood-thinning medications, including prescription anticoagulants and antiplatelet drugs like aspirin, which can increase bleeding risk.
Discontinue Before Surgery: Nattokinase should be discontinued at least two weeks before any scheduled surgery, including dental procedures, to prevent excessive bleeding.
Requires Professional Consultation: It is critical to consult a healthcare provider before starting daily nattokinase, especially if you have pre-existing health conditions or take other medications.
Not a Replacement for Prescriptions: Nattokinase must not be used as a substitute for prescribed blood-thinning medication without specific medical supervision.
Watch for Allergic Reactions: Individuals with a soy allergy may have an allergic reaction to nattokinase supplements.
Dosage is Important: Stick to the manufacturer's or healthcare provider's recommended dosage (commonly 2,000 FU daily), as very high doses could increase risks.

Nattokinase is an enzyme extracted from natto, a traditional Japanese food made from fermented soybeans using the bacterium Bacillus subtilis. It is known for its ability to help break down fibrin, a protein involved in blood clot formation, and is used as a dietary supplement for cardiovascular support. Understanding the safety of daily use is important.

General Safety for Daily Use

For most healthy individuals, daily nattokinase at recommended doses is considered safe. Studies, including human clinical trials, suggest a low risk of adverse effects with daily use for up to three years. The long history of consuming natto as a food also supports its general safety profile at dietary levels.

Key Considerations and Potential Risks

Despite its general safety for healthy individuals, nattokinase has blood-thinning effects that necessitate caution in certain groups.

Interactions with Blood-Thinning Medications

Taking nattokinase with medications that affect blood clotting is the most significant risk. This combination can increase the risk of bruising and bleeding when combined with prescription blood thinners like warfarin, heparin, or antiplatelet drugs such as aspirin. Serious adverse events have been reported in individuals taking nattokinase with blood thinners or substituting it for prescribed medication. Never replace prescribed medication with nattokinase without medical advice.

Pre-operative Precautions

Stop nattokinase use at least two weeks before any surgery to avoid excessive bleeding complications.

Allergic Reactions

Soy-allergic individuals may react to nattokinase, as it is soy-derived.

Cautions for Specific Groups

Avoid nattokinase if you have a bleeding disorder like hemophilia due to increased hemorrhage risk. It should also be avoided during pregnancy and breastfeeding due to insufficient safety studies. Nattokinase may lower blood pressure. Monitor levels if you have low blood pressure or take blood pressure medication.

Nattokinase Dosage and Supplement Quality

A typical daily dose in studies is around 2,000 Fibrinolytic Units (FU). Dosage can vary, and supplement quality is important. Enteric-coated capsules may improve absorption. For more information on nattokinase, consult the {Link: National Institutes of Health website https://pmc.ncbi.nlm.nih.gov/articles/PMC6043915/}.

Comparison Table: Nattokinase vs. Standard Blood Thinners


Feature	Nattokinase (Supplement)	Prescription Anticoagulants (e.g., Warfarin)
Mechanism	Breaks down fibrin and promotes blood fluidity.	Inhibits clotting factors or blocks enzymes to prevent clot formation.
Regulation	Dietary supplement; manufacturers responsible for safety.	FDA-approved and rigorously tested.
Risk Profile	Generally low for healthy individuals; increased bleeding risk with drug interactions.	Higher risk profile; requires regular blood monitoring.
Medical Supervision	Crucial to consult a doctor before use, especially with other medications.	Absolutely required and controlled by a healthcare provider.
Food Source	Fermented soybeans (natto).	Synthetic compounds.

Conclusion

Daily nattokinase at recommended doses appears safe for healthy individuals not taking blood-clotting medications, with studies up to three years. However, its blood-thinning properties require caution. The risk of dangerous bleeding is high for those on prescription anticoagulants or antiplatelet drugs. Avoid use if you have bleeding disorders, are having surgery, or are pregnant/breastfeeding. Always consult a healthcare provider before starting nattokinase to ensure it's safe for your health situation and never substitute it for prescribed medication without their approval.

Frequently Asked Questions

No, nattokinase is not safe for everyone. While generally safe for healthy individuals at recommended doses, it is contraindicated for people on blood thinners, those with bleeding disorders, and those preparing for surgery.

A common recommended dosage for nattokinase is approximately 2,000 Fibrinolytic Units (FU). However, it is best to follow the manufacturer's instructions or a healthcare provider's recommendation.

No, it is not recommended to take nattokinase with prescription blood thinners like warfarin, heparin, or antiplatelet drugs such as aspirin. The combination significantly increases the risk of excessive bleeding and should only be done under strict medical supervision.

It is advised to stop taking nattokinase at least two weeks before any scheduled surgery, including dental procedures. This precaution helps to minimize the risk of excessive bleeding during and after the operation.

Yes, allergic reactions are possible, particularly for individuals with a soy allergy, since nattokinase is derived from fermented soybeans. These reactions can range from mild symptoms to severe anaphylaxis.

For healthy individuals, side effects are rare at recommended doses. However, potential risks, especially when taken with other blood thinners or at very high doses, include increased bruising, excessive bleeding, and a drop in blood pressure.

While some studies indicate nattokinase may have beneficial effects on blood flow, blood pressure, and managing atherosclerosis, more extensive clinical evidence is needed. It should not be considered a treatment for cardiovascular conditions without medical supervision.

Nattokinase supplements are often sold with vitamin K2 removed to prevent interference with warfarin therapy. Natto, the food source, contains high levels of vitamin K2, which supports blood clotting and can counteract the effects of warfarin.