Drug & supplement interaction

Liver Extract + Warfarin

Warfarin brand name: Warfarin.

Minor Interaction
Medically reviewed by · Updated July 2026
The bottom line Minor

Liver Extract has a minor interaction with Warfarin. Liver extract products may contain small and variable amounts of vitamin K.

Read the full interaction report
SeverityMinor
LikelihoodPossible
EvidenceC
What do Severity, Likelihood & Evidence mean?
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Interaction report

Liver Extract and Warfarin

Here is the interaction we found between these two, with the evidence behind it.

Minor

Warfarin (Coumadin)

Liver extract products may contain small and variable amounts of vitamin K. Theoretically, starting, stopping, or substantially changing the amount of liver extract used could reduce the anticoagulant effect of warfarin and lower the INR. However, this interaction has not been directly studied or reported in humans, and the vitamin K content of liver extract products is generally not standardized. Consider monitoring the INR after a meaningful change in liver extract use.
Severity Minor Likelihood Possible Evidence C

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the thing to know about pairing liver extract with your warfarin. Animal liver can carry vitamin K, and vitamin K is exactly what warfarin works against to keep your blood thin. So if a liver extract product contains meaningful vitamin K, in theory it could nudge your warfarin toward working a little less, which would show up as a lower INR and, over time, a higher clot risk. It won't make warfarin stronger.

Now, I want to keep this in perspective. This is a theoretical concern, not something proven in people, and liver extract products aren't standardized, so the vitamin K amount varies a lot. Because warfarin has such a narrow safety window, consistency matters most. If you start, stop, or change how much you take, tell your pharmacist or doctor so they can check your INR.

Contact Dr. Brian directly if you have additional questions on this interaction

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Liver Extract Also Interacts With Other Medications

Liver Extract has 2 minor known drug interactions in our database — the Warfarin one above is one of them. If you take anything else, check it against the full list below.

Minor 2 No known interaction 2,828 (incl. Warfarin)
Taking anything else?

Check Another of Your Medications Against Liver Extract

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

From our Q&A

Questions About Liver Extract or Warfarin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Liver Extract or Warfarin, 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 Warfarin

This page covers Liver Extract only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Warfarin page lists 361 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Alfalfa (major), American Ginseng (major), Beer (major) and Cannabis (major).

By severity: 16 major · 301 moderate · 44 minor.

From our pharmacist’s overview on the Warfarin page

“People take warfarin to prevent dangerous clots, and many are the same people reaching for glucosamine for sore joints or a multivitamin containing vitamin K, which makes this a list that deserves genuine respect. Of the 361 supplements on file for warfarin, 16 carry a major rating, and the danger runs in both directions: some add to w…”

Reviewed by 2 · Jul 18, 2026

Open the Warfarin interaction page

One more smart check

Taking Liver Extract as Part of a Dietary Supplement Product? Check It for Interactions

We hold 595 real supplement products containing Liver Extract, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Liver Extract. Your product may carry other ingredients that interact with Warfarin too, on top of Liver Extract — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Liver Extract and Warfarin 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 Liver Extract
Top 25%

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

29 days ago today
Medication Warfarin
Top 10

#4 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.

Supplement

About Liver Extract

What is Liver Extract?

  • Anemia and low iron
  • Vitamin B12 support
  • General energy and fatigue
  • Nutritional support for athletes
  • Liver health support

Liver extract is a dried or concentrated form of animal liver that is naturally rich in iron, vitamin B12, vitamin A, and other nutrients. It was once used to treat certain anemias before purified vitamins became available, but today there is little modern evidence that it offers benefits beyond what a balanced diet or standard supplements provide. Talk with your pharmacist or doctor before using it, especially if you are pregnant, have liver disease, or have iron overload conditions.

Read the full Liver Extract monograph & all interactions
Medication

About Warfarin

What Is Warfarin Used For?

Brand name: Warfarin

Warfarin sodium tablets and Jantoven tablets are both used to prevent and treat venous thrombosis (blood clots in the veins) and pulmonary embolism (a clot in the lungs). They are also used to prevent clot-related complications in people with atrial fibrillation (an irregular heart rhythm) or who have had a heart valve replaced.

In people who have had a heart attack, warfarin is used to reduce the risk of death, another heart attack, stroke, or other clotting events. It does not dissolve an existing clot, but it helps prevent the clot from growing and stops new dangerous clots from forming.

See full Warfarin drug information
Keep checking

Other Drugs & Liver Extract

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

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

2 interactions

No interaction 2,827 drugs checked — show the list

We also checked Liver Extract 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 Liver Extract list.

See the full Liver Extract interactions page
See every supplement checked against Warfarin, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

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

Keep exploring
Liver Extract monograph › Uses, safety, and every drug interaction in one place Warfarin supplement interactions › Every supplement checked against Warfarin, ranked by severity Warfarin drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Liver Extract and Warfarin Together: Common Questions

Can you take Liver Extract with Warfarin?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Liver Extract and Warfarin interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

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

Still Have a Question About Warfarin and Liver Extract?

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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.