Drug & supplement interaction

Vitamin K + Dutasteride

Dutasteride brand name: Avodart.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Vitamin K and Dutasteride in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first.

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Interaction report

Vitamin K and Dutasteride

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Dutasteride and Vitamin K in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Vitamin K safety at a glance

Vitamin K overall Generally safe Generally safe in amounts found in food and most supplements for healthy people.
Pregnancy Likely Safe When used orally in amounts that do not exceed the daily adequate intake level (AI). A tolerable upper intake level for vitamin K in pregnancy and lactation has... Read the full pregnancy detail
Breastfeeding Likely Safe When used orally in amounts that do not exceed the daily adequate intake level (AI). A tolerable upper intake level for vitamin K in pregnancy and lactation has... Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Dutasteride and Vitamin K? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Dutasteride

Interactions in our licensed database are recorded against drug classes, not just single drug names. Dutasteride is filed under 2 classifications — cytochrome p450 3a4 (cyp3a4) substrates, oral drugs. Vitamin K has documented interactions with 1 drug class — the most serious being warfarin (coumadin) (major) — and none of Dutasteride’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Vitamin K Does Interact With Other Medications

Vitamin K has 2 major, known drug interactions in our database — Dutasteride isn’t one of them. If you take anything else, check it against the full list below.

Major 2 No known interaction 2,828 (incl. Dutasteride)
Taking anything else?

Check Another of Your Medications Against Vitamin K

Covers the 2,830 medications we’ve checked against Vitamin K. Pick one to open its full report.

What to actually watch for

What Vitamin K Itself Has Been Linked To

This is not an interaction — nothing below involves Dutasteride. It is the side-effect record for Vitamin K on its own, from the licensed Natural Medicines monograph. If something new turns up after you add Vitamin K, this list is the first place to look. 3 entries are worth acting on rather than waiting out — marked below.

  • Yellowing of the skin or eyes / Liver problems Worth acting on Additional detail

    “Orally, vitamin K3 (menadione) has been linked to hepatotoxicity. Vitamin K3 is no longer used therapeutically in North America because it has been linked to hepatic toxicity and jaundice in animal research.”

    Vitamin K · Natural Medicines adverse-effect record, reported in neonatal jaundice.

    1 source cited
    1. 7135. 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.
  • A severe allergic reaction Worth acting on Additional detail

    “Intravenously, vitamin K can cause reactions that resemble hypersensitivity or anaphylaxis. These reactions are rare. It is unclear whether the adverse effect is caused by the drug or a component of the solution. There have been very rare cases of hyperbilirubinemia, particularly in premature neonates, following large doses of vitamin K (15).”

    Vitamin K · Natural Medicines adverse-effect record, reported in myasthenia gravis.

    3 sources cited
    1. 85389. 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
    2. 15. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
    3. 112100. 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
  • An allergic reaction Worth acting on Additional detail

    Recorded for Vitamin K in the same Natural Medicines adverse-effect record shown under A severe allergic reaction above.

  • Stomach upset Additional detail

    Recorded for Vitamin K in the same Natural Medicines adverse-effect record shown under A severe allergic reaction above.

  • Stomach pain Additional detail

    “Orally, vitamin K can cause mild to moderate gastrointestinal side effects. The most common effects include nausea, abdominal pain, and diarrhea.”

    Vitamin K · Natural Medicines adverse-effect record, reported in diarrhea.

    2 sources cited
    1. 91450. 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.
    2. 91451. 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
  • Diarrhea / Nausea Additional detail

    Recorded for Vitamin K in the same Natural Medicines adverse-effect record shown under A severe allergic reaction above.

Everything above comes from the Natural Medicines adverse-effect record for Vitamin K — expand a row for the licensed statement it rests on. We read the ADVERSE REACTIONS section of Dutasteride’s FDA label too, and the two lists don’t meaningfully overlap — which is why no Dutasteride column appears here.

Special populations

Vitamin K in Pregnancy & Breastfeeding

Pregnancy And Lactation Likely Safe

When used orally in amounts that do not exceed the daily adequate intake level (AI). A tolerable upper intake level for vitamin K in pregnancy and lactation has not been set.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

Overlapping uses

What Dutasteride Is Prescribed For, and What Vitamin K Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Dutasteride is a prescription medicine with approved uses on its FDA label. Vitamin K is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Dutasteride is prescribed for: Dutasteride capsules are used to treat symptomatic benign prostatic hyperplasia (BPH) — a non-cancerous enlargement of the prostate — in men. Treatment can help improve urinary symptoms, lower the risk of sudden urinary retention (being completely unable to urinate), and reduce the likelihood of needing BPH-related surgery. Dutasteride capsules can also be used in combination with tamsulosin (an alpha-blocker) to treat symptomatic BPH in men with an enlarged prostate. Importantly, dutasteride is not approved for the prevention of prostate cancer.

Vitamin K has been studied for:

  • Prostate cancer studied, not established Vitamin K has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Vitamin K for prostate cancer

    It is unclear if dietary intake of vitamin K reduces the risk of prostate cancer.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Dutasteride on your own; if you are taking Vitamin K for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Vitamin K or Dutasteride

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Vitamin K or Dutasteride, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Dutasteride

This page covers Vitamin K only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Dutasteride page lists 138 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Grapefruit (major), St. John's Wort (major), Acacia Rigidula (moderate) and Adrafinil (moderate).

By severity: 3 major · 94 moderate · 41 minor.

Open the Dutasteride interaction page

One more smart check

Taking Vitamin K as Part of a Dietary Supplement Product? Check It for Interactions

We hold 5,292 real supplement products containing Vitamin K, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Vitamin K. Even though Vitamin K itself has no known interaction with Dutasteride, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Vitamin K and Dutasteride Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Vitamin K
Top 5%

#27 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Dutasteride
Top half

#736 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Vitamin K reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Vitamin K and Dutasteride records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Vitamin K

What is Vitamin K?

  • Supporting normal blood clotting
  • Bone health
  • Heart and vascular health
  • Correcting vitamin K deficiency
  • Newborn bleeding prevention (medical injection)

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 or bone and heart health, where evidence is mixed. If you take a blood thinner, talk to your pharmacist or doctor before changing your vitamin K intake.

Fat-soluble vitamin (K1 from plants, K2 from animal sources and bacteria) · Capsules, softgels, tablets, drops, injections (medical use)

An interaction check asks whether these two react with each other — it does not ask whether Vitamin K is a good idea for someone in your situation. Here is what our Vitamin K record says about it on its own.

Vitamin K: dosing

There is no single "best" supplement dose for everyone, and needs vary by age, sex, and health status. Nutrition authorities have set general daily intake recommendations for vitamin K that most people can meet through diet.If you choose to take a supplement, follow the directions on the product label and do not take more than recommended without medical advice.

From our Vitamin K monograph — the full record covers uses, side effects and every documented interaction.

Read the full Vitamin K monograph & all interactions
Medication

About Dutasteride

What Is Dutasteride Used For?

Brand name: Avodart

Dutasteride capsules are used to treat symptomatic benign prostatic hyperplasia (BPH) — a non-cancerous enlargement of the prostate — in men. Treatment can help improve urinary symptoms, lower the risk of sudden urinary retention (being completely unable to urinate), and reduce the likelihood of needing BPH-related surgery.

Dutasteride capsules can also be used in combination with tamsulosin (an alpha-blocker) to treat symptomatic BPH in men with an enlarged prostate. Importantly, dutasteride is not approved for the prevention of prostate cancer.

Most-Reported Side Effects for Dutasteride

From FAERS, the FDA’s public side-effect reporting system (9,120 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Dyspnea 838 reports
Fatigue 666 reports
Diarrhea 596 reports
Dizziness 565 reports
Asthenia 533 reports
See full Dutasteride drug information
Keep checking

Other Drugs & Vitamin K

Browse every other medication we’ve checked against Vitamin K — both the ones with a known interaction and the ones without. Select any drug for the full detail.

2Major
0Moderate
0Minor
2,827No known interaction
2 Major 2,827 No interaction
Major

2 interactions

No interaction 2,827 drugs checked — show the list

We also checked Vitamin K against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,827 medications checked with no known interaction — see the full Vitamin K list.

See the full Vitamin K interactions page
See every supplement checked against Dutasteride, ranked by severity
Evidence & sources

Vitamin K References

The 11 references that drive our Vitamin K monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  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

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Vitamin K and Dutasteride Together: Common Questions

Is it safe to take Vitamin K with Dutasteride?
We do not list a known interaction between Vitamin K and Dutasteride. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Are Vitamin K and Dutasteride used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Vitamin K in each. That is a conversation for your prescriber, especially if Dutasteride is being adjusted to a target.
How was the Vitamin K and Dutasteride combination checked?
Interactions in our licensed database are recorded against drug classes. Dutasteride is filed under 2 classifications, and Vitamin K has documented interactions with 1 drug class — none of Dutasteride's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Vitamin K interact with any other medications?
Yes. Vitamin K has 2 documented drug interactions in our database — Dutasteride is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Dutasteride interact with any supplements?
Yes. Dutasteride has documented interactions with 138 supplements in our database — Vitamin K is not one of them. The Dutasteride interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Vitamin K monograph Uses, safety profile, and every drug interaction in one place Dutasteride drug information The full plain-English guide to this medication Dutasteride supplement interactions Every supplement checked against Dutasteride, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 11 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Dutasteride and Vitamin K?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.