Drug & supplement interaction

Watercress + Warfarin Sodium

Warfarin Sodium brand names: Coumadin, Panwarfin, Sofarin.

Moderate Interaction
The bottom line Moderate

Watercress has a moderate interaction with Warfarin Sodium. Watercress contains vitamin K. Consuming large amounts of watercress might antagonize the anticoagulant effects of warfarin.

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

Watercress and Warfarin Sodium

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

Moderate

WARFARIN (Coumadin)

Watercress contains vitamin K. Consuming large amounts of watercress might antagonize the anticoagulant effects of warfarin.
Severity Moderate Likelihood Possible Evidence B

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 with warfarin and watercress: watercress is fairly high in vitamin K, and vitamin K is exactly what warfarin works against to thin your blood. So eating a lot of watercress can push back on warfarin and make it less effective, which means your blood could clot more easily than your doctor intends. That's the opposite of what you want when you're taking it to prevent strokes or clots.

The good news is that consistency matters more than avoidance. You don't have to skip watercress, just don't suddenly load up on big amounts or change how much you eat day to day. Big swings are what throw off your INR. Loop in your pharmacist or doctor before adding any concentrated watercress extract, and keep up with your regular INR checks.

References
  1. Bolton-Smith C, Price RJ, Fenton ST, et al. Compilation of a provisional UK database for the phylloquinone (vitamin K1) content of foods. Br J Nutr 2000;83:389-99.

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

Watercress Also Interacts With Other Medications

Watercress has 5 moderate known drug interactions in our database — the Warfarin Sodium one above is one of them. If you take anything else, check it against the full list below.

Taking anything else?

Check Another of Your Medications Against Watercress

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

From our Q&A

Questions About Watercress or Warfarin Sodium

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

This page covers Watercress only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Warfarin Sodium 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).

Open the Warfarin Sodium interaction page

One more smart check

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

We hold 820 real supplement products containing Watercress, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Watercress. Your product may carry other ingredients that interact with Warfarin Sodium too, on top of Watercress — 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 Watercress and Warfarin Sodium 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 Watercress
Top 25%

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

29 days ago today
Medication Warfarin Sodium
Top 1%

#20 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 Watercress

What is Watercress?

Watercress
  • Source of vitamins and minerals
  • Antioxidant support
  • General nutrition
  • Traditional cough and congestion remedy
  • Skin and detox tonics

Watercress is a nutrient-rich leafy green that provides vitamins A, C, and K plus minerals and antioxidant plant compounds. Eaten as a food it is generally safe and healthy for most people, but strong human evidence for concentrated supplement health claims is limited. Talk to your pharmacist or doctor before using high-dose extracts, especially if you are pregnant, breastfeeding, or have a medical condition.

Read the full Watercress monograph & all interactions
Medication

About Warfarin

What Is Warfarin Used For?

Brand names: Coumadin, Panwarfin, Sofarin

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 & Watercress

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

0Major
5Moderate
0Minor
2,824No known interaction
Moderate

5 interactions

No interaction 2,824 drugs checked — show the list
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

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Pharmacist Counseling Corner

Taking Watercress and Warfarin Sodium Together: Common Questions

Can you take Watercress with Warfarin Sodium?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Watercress and Warfarin Sodium interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

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

Still Have a Question About Warfarin Sodium and Watercress?

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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.