Drug & supplement interaction

Sweet Clover + Warfarin Sodium

Warfarin Sodium brand names: Coumadin, Panwarfin, Sofarin.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Sweet Clover has a moderate interaction with Warfarin Sodium. Theoretically, fresh sweet clover might increase the risk of bleeding when used with anticoagulant or antiplatelet drugs.

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

Sweet Clover and Warfarin Sodium

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

Moderate

ANTICOAGULANT/ANTIPLATELET DRUGS

Why this applies to Warfarin Sodium

Warfarin Sodium falls under ANTICOAGULANT/ANTIPLATELET DRUGS — the group Sweet Clover interacts with.

Theoretically, fresh sweet clover might increase the risk of bleeding when used with anticoagulant or antiplatelet drugs.
Fresh sweet clover contains coumarinic acids, which are converted to free coumarins during drying. Dicoumarol, which has anticoagulant activity, also has been found in some sweet clover preparations and can be formed if fresh sweet clover is allowed to spoil.
Severity Moderate Likelihood Possible Evidence D

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 simple version: warfarin already thins your blood, and sweet clover contains coumarin compounds that can act in the same direction. The real concern is dicoumarol, a true blood thinner that can form when sweet clover spoils or isn't dried properly. Stacked on top of your warfarin, that could push you toward too much thinning, meaning easy bruising, nosebleeds, bleeding gums, or more serious internal bleeding.

To be fair, this warning is theoretical and based on the plant's chemistry, not strong human studies. But warfarin is a narrow-margin drug where even small shifts can change your INR. I wouldn't combine the two without checking first. Please talk with your pharmacist or doctor before using sweet clover.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Monographs on the medicinal uses of plant drugs. Exeter, UK: European Scientific Co-op Phytother, 1997.
  2. Wichtl MW. Herbal Drugs and Phytopharmaceuticals. Ed. N.M. Bisset. Stuttgart: Medpharm GmbH Scientific Publishers, 1994.
  3. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

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

Sweet Clover Also Interacts With Other Medications

Sweet Clover has 479 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.

Moderate 479 No known interaction 2,351 (incl. Warfarin Sodium)
Taking anything else?

Check Another of Your Medications Against Sweet Clover

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

From our Q&A

Questions About Sweet Clover 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 Sweet Clover 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 Sweet Clover 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 Sweet Clover as Part of a Dietary Supplement Product? Check It for Interactions

We hold 26 real supplement products containing Sweet Clover, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Sweet Clover. Your product may carry other ingredients that interact with Warfarin Sodium too, on top of Sweet Clover — 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 Sweet Clover 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 Sweet Clover
Steady interest

#1,375 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Warfarin Sodium
Top 1%

#18 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 Sweet Clover

What is Sweet Clover?

Sweet Clover
  • Varicose veins and poor circulation
  • Leg swelling (edema)
  • Hemorrhoids
  • Bruising and minor inflammation
  • Respiratory complaints

Sweet clover is a traditional European herb most often promoted for vein problems and leg swelling, but high-quality human evidence is limited. It contains coumarin, which can become dangerous if the plant spoils, so quality matters and you should talk to a pharmacist before using it.

Read the full Sweet Clover 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 & Sweet Clover

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

0Major
479Moderate
0Minor
2,350No known interaction
479 Moderate 2,350 No interaction
Moderate

479 interactions

Showing 60 of 479 moderate interactions — see all 479 on the Sweet Clover page.

No interaction 2,350 drugs checked — show the list

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

Showing the 60 most looked-up of 2,350 medications checked with no known interaction — see the full Sweet Clover list.

See the full Sweet Clover interactions page
See every supplement checked against Warfarin Sodium, 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
Sweet Clover monograph › Uses, safety, and every drug interaction in one place Warfarin Sodium supplement interactions › Every supplement checked against Warfarin Sodium, 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 Sweet Clover and Warfarin Sodium Together: Common Questions

Can you take Sweet Clover 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 Sweet Clover 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 Sweet Clover?

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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.