Drug & supplement interaction

Sweet Vernal Grass + Defibrotide Sodium

Defibrotide Sodium brand name: Defitelio.

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

Sweet Vernal Grass has a moderate interaction with Defibrotide Sodium. Hay prepared from dried sweet vernal grass contains an anticoagulant, dicoumarol, which has been associated with fatal hemorrhages in animals.

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

Sweet Vernal Grass and Defibrotide Sodium

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

Moderate

ANTICOAGULANT/ANTIPLATELET DRUGS

Why this applies to Defibrotide Sodium

Defibrotide Sodium falls under ANTICOAGULANT/ANTIPLATELET DRUGS — the group Sweet Vernal Grass interacts with.

Hay prepared from dried sweet vernal grass contains an anticoagulant, dicoumarol, which has been associated with fatal hemorrhages in animals. Theoretically, taking dried sweet vernal grass might cause additive effects and side effects with drugs having anticoagulant or antiplatelet properties.
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 gist with Defibrotide: it's a clot-preventing medicine, and Sweet Vernal Grass naturally contains coumarin, which can break down into dicoumarol, a blood-thinning substance. Stacking the two could, in theory, add up and make you bleed more easily. With defibrotide that might look like easier bruising, nosebleeds, bleeding gums, or more serious internal bleeding, which is already a known risk with this drug.

I want to be honest, though: this concern is theoretical, based on animal reports and pharmacology rather than real cases in people. The aroma alone won't matter. Since defibrotide is given in a hospital to seriously ill transplant patients, please flag any supplement use to your care team before adding it.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
  2. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 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 Vernal Grass Also Interacts With Other Medications

Sweet Vernal Grass has 121 moderate known drug interactions in our database — the Defibrotide Sodium one above is one of them. If you take anything else, check it against the full list below.

Moderate 121 No known interaction 2,709 (incl. Defibrotide Sodium)
Taking anything else?

Check Another of Your Medications Against Sweet Vernal Grass

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

Everything else you take

See Every Supplement That Interacts With Defibrotide Sodium

This page covers Sweet Vernal Grass only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Defibrotide Sodium page lists 202 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Danshen (major), Piracetam (major), Aconite (moderate), Allspice (moderate) and Aloe (moderate).

By severity: 2 major · 183 moderate · 17 minor.

From our pharmacist’s overview on the Defibrotide Sodium page

“Defibrotide (Defitelio) is an intravenous drug for severe veno-occlusive disease of the liver after a stem cell transplant, and part of how it works is by reducing the blood's tendency to clot. That makes bleeding the single thread running through this entire list, and it deserves real care.”

Reviewed by 2 · Jul 18, 2026

Open the Defibrotide Sodium interaction page

How much people look this up

Where Sweet Vernal Grass and Defibrotide 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 Vernal Grass
Top half

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

29 days ago today
Medication Defibrotide Sodium
Top half

#1,176 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 Vernal Grass

What is Sweet Vernal Grass?

  • Trouble sleeping
  • Mild anxiety or restlessness
  • Hay fever and allergy symptoms (as a known trigger, sometimes studied)
  • Used as a fragrant flavoring in foods and drinks
  • Folk use for nausea or upset stomach

Sweet Vernal Grass is a fragrant European meadow grass best known for the sweet, hay-like smell it gets from coumarin. It has a long history as a flavoring and a folk calming remedy, but there is very little human research to support any health benefit. It is also a well-known cause of grass-pollen allergies, so people prone to hay fever should be cautious.

Read the full Sweet Vernal Grass monograph & all interactions
Medication

About Defibrotide Injection

What Is Defibrotide Injection Used For?

Brand name: Defitelio

Defitelio (defibrotide injection) is used to treat hepatic veno-occlusive disease (VOD) — also called sinusoidal obstruction syndrome (SOS) — in adult and pediatric patients. This is a serious condition where small blood vessels in the liver become blocked, most often after a hematopoietic stem-cell transplant (HSCT).

Defitelio is specifically indicated when VOD is accompanied by kidney dysfunction or pulmonary (lung) dysfunction, making it a treatment for one of the most severe forms of this complication.

See full Defibrotide Injection drug information
Keep checking

Other Drugs & Sweet Vernal Grass

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

0Major
121Moderate
0Minor
2,708No known interaction
121 Moderate 2,708 No interaction
Moderate

121 interactions

Showing 60 of 121 moderate interactions — see all 121 on the Sweet Vernal Grass page.

No interaction 2,708 drugs checked — show the list

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

Showing the 60 most looked-up of 2,708 medications checked with no known interaction — see the full Sweet Vernal Grass list.

See the full Sweet Vernal Grass interactions page
See every supplement checked against Defibrotide 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 Vernal Grass monograph › Uses, safety, and every drug interaction in one place Defibrotide Sodium supplement interactions › Every supplement checked against Defibrotide Sodium, ranked by severity Defibrotide Injection 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 Vernal Grass and Defibrotide Sodium Together: Common Questions

Can you take Sweet Vernal Grass with Defibrotide 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 Vernal Grass and Defibrotide 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 Defibrotide Sodium and Sweet Vernal Grass?

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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.