Herb & supplement monograph

Sweet Clover Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Sweet Clover interacts with medications. The heart of this page is the interaction list — every drug Sweet Clover is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Sweet Clover is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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On this page

Sweet Clover Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Sweet Clover drug interaction appears low for most people, because the known concerns are theoretical rather than proven in humans. Every listed interaction is rated moderate rather than major, and none has been confirmed in well-controlled human studies.

Interactions deserving the most attention

The combination we watch most closely is Sweet Clover taken with blood thinners, meaning anticoagulant and antiplatelet drugs. Sweet clover naturally contains coumarin-type compounds, and if the plant spoils it can form dicoumarol, a substance with real blood-thinning activity, so an added bleeding risk cannot be ruled out. We also keep an eye on medications that can stress the liver, since large amounts of sweet clover have caused temporary liver irritation in a few susceptible people.

What the rest of the list means

The long list of interacting medications reflects these two broad drug groups rather than hundreds of separate problems. The concerns are based on what sweet clover's plant compounds could do in theory, not on documented harm in people taking these combinations, so most people are unlikely to notice any effect.

Check your medications against Sweet Clover

Based on HelloPharmacist’s Sweet Clover interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Sweet Clover

482 medications have a known interaction with Sweet Clover, graded by severity. Select any drug for the full evidence-based detail.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Sweet Clover using our pharmacist-reviewed interaction data.

AI summaries are generated from our Sweet Clover interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. Interaction 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.
Possible. 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
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Sweet Clover combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Sweet Clover affects

Every type of medication (drug category) Sweet Clover is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 2 drug categories Sweet Clover interacts with

Anticoagulant/antiplatelet DrugsHepatotoxic Drugs

Anticoagulant/Antiplatelet Drugs

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.

Likelihood Possible Evidence D

Hepatotoxic Drugs

Theoretically, concomitant use of sweet clover with hepatoxic drugs might increase the risk of hepatotoxicity.
Orally, large amounts of sweet clover can cause transient liver injury in susceptible individuals, possibly due to coumarin content. In one case report, a patient with multiple sclerosis developed jaundiced palms and a slight elevation in serum alanine aminotransferase (ALT) after taking sweet clover containing coumarin 10 mg daily for 3 years. Two weeks after starting therapy with subcutaneous interferon (IFN)-beta 1b, aspartate transaminase (AST) and ALT levels increased to 7 and 17 times the upper limit of normal, respectively. Levels normalized after discontinuation of both products. Subsequent use of IFN-beta 1a alone, without sweet clover, resulted in only a very slight increase in AST.

Likelihood Possible Evidence D

Monograph

Sweet Clover: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

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.

Scientific name: Melilotus officinalis
Family: Fabaceae
Part used: Above-ground parts (flowering tops, leaves, and stems)
Common forms: Tea, dried herb, capsules, tincture, topical creams and ointments

People commonly use it for

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

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallUse caution

Generally used in small amounts, but its coumarin content can affect bleeding and the liver, so use cautiously.

PregnancyInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full pregnancy detail

BreastfeedingInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

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Overview

Sweet clover (Melilotus officinalis) is a tall, leafy plant in the pea family (Fabaceae) that produces small yellow flowers. It is native to Europe and Asia but now grows in many parts of the world, including North America, where it is common along roadsides and in fields.

The plant has a distinctive sweet, hay-like smell that comes from a natural compound called coumarin. People have used the flowering tops and leaves for a long time in traditional medicine, mostly as a tea, tincture, or topical preparation. A closely related plant, white sweet clover (Melilotus albus), is also used.

How it works

Sweet clover contains coumarin and related compounds. Coumarin may help support the tone of vein walls and reduce fluid buildup, which is why the plant has been used for swelling and circulation problems. Some research also points to mild anti-inflammatory and antioxidant effects.

Importantly, when sweet clover spoils or ferments (for example in poorly dried hay), molds can convert coumarin into dicoumarol, a compound that thins the blood. This discovery actually led to the development of modern blood-thinning medicines. Most of what we know about these mechanisms comes from laboratory and animal studies, not large human trials.

Effectiveness

Does Sweet Clover work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 7 uses evaluated

7 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

For Sweet Clover, current evidence isn’t strong enough to rate any specific use. The conditions it has been studied for are listed below.

Also studied for 7 conditions — evidence insufficient to rate

Insufficient Reliable Evidence To Rate Bruises