Drug & supplement interaction

English Ivy + Warfarin

Warfarin brand name: Warfarin.

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

Warfarin falls into 2 drug categories that English Ivy can interact with; the most serious is rated moderate. Theoretically, English ivy might increase the levels of drugs metabolized by CYP2C19.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

English Ivy and Warfarin

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

English Ivy interacts with whole categories of medication. Warfarin falls into 2 of those categories, so it can interact with English Ivy in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES

1 of 2

Why this applies to Warfarin

Warfarin falls under CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES — the group English Ivy interacts with.

Theoretically, English ivy might increase the levels of drugs metabolized by CYP2C19.
In vitro research shows that English ivy inhibits CYP2C19 enzymes. So far, this interaction has not been reported in humans.
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 is one of those medicines where the dose has to be just right, since too much raises your bleeding risk and too little lets clots form. Lab studies suggest the saponins in English ivy may slow down a liver enzyme called CYP2C19, which helps clear part of your warfarin. In theory, that could let warfarin build up a bit and push your blood toward being too thin.

I want to be honest though: this is only test-tube research, and it has never actually been reported in real people taking warfarin. So I wouldn't lose sleep over it, but watch for easy bruising, bleeding gums, or nosebleeds. Before adding an ivy cough product, just give your pharmacist or doctor a quick heads-up so your INR can be checked if needed.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Rehman SU, Kim IS, Choi MS, Kim SH, Zhang Y, Yoo HH. Time-dependent Inhibition of CYP2C8 and CYP2C19 by Hedera helix Extracts, A Traditional Respiratory Herbal Medicine. Molecules. 2017;22(7). PubMed
Moderate

CYTOCHROME P450 2C8 (CYP2C8) SUBSTRATES

2 of 2

Warfarin also falls under CYTOCHROME P450 2C8 (CYP2C8) SUBSTRATES.

Theoretically, English ivy might increase the levels of drugs metabolized by CYP2C8.
In vitro research shows that English ivy inhibits CYP2C8 enzymes. So far, this interaction has not been reported in humans.
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 situation with warfarin and English ivy. Lab (test tube) studies suggest English ivy can block an enzyme called CYP2C8. In theory, slowing that enzyme could let a drug it clears build up a bit. The catch is that warfarin is mainly handled by other liver enzymes (especially CYP2C9), so CYP2C8 plays only a small role here. Honestly, this is a theoretical concern that has never actually been reported in people.

Still, warfarin is a touchy drug where small shifts can change your INR and raise bleeding risk (think easy bruising, nosebleeds, or blood in urine or stool). Because of that narrow margin, please loop in your pharmacist or doctor before adding any ivy cough product, and keep up with your INR checks.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Rehman SU, Kim IS, Choi MS, Kim SH, Zhang Y, Yoo HH. Time-dependent Inhibition of CYP2C8 and CYP2C19 by Hedera helix Extracts, A Traditional Respiratory Herbal Medicine. Molecules. 2017;22(7). PubMed

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

English Ivy Also Interacts With Other Medications

English Ivy has 279 moderate known drug interactions in our database — the Warfarin one above is among them. If you take anything else, check it against the full list below.

Moderate 279 No known interaction 2,551 (incl. Warfarin)
Taking anything else?

Check Another of Your Medications Against English Ivy

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

From our Q&A

Questions About English Ivy 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 English Ivy 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 English Ivy 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 English Ivy as Part of a Dietary Supplement Product? Check It for Interactions

We hold 118 real supplement products containing English Ivy, each one broken down to its full ingredient list — and combination products often carry several ingredients besides English Ivy. Your product may carry other ingredients that interact with Warfarin too, on top of English Ivy — 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 English Ivy 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 English Ivy
Steady interest

#1,052 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 English Ivy

What is English Ivy?

English Ivy
  • Cough and chest congestion
  • Bronchitis
  • Asthma symptoms
  • Sore throat
  • Skin irritation

English ivy leaf extract is most commonly used in cough and cold syrups to help loosen mucus and ease coughing, and it is a popular ingredient in many European herbal products. Some research suggests it may help with certain coughs, but the evidence is still limited and mixed. The raw plant is poisonous if eaten and can irritate skin, so only use properly prepared commercial products and check with your pharmacist first.

Read the full English Ivy 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 & English Ivy

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

0Major
279Moderate
0Minor
2,550No known interaction
279 Moderate 2,550 No interaction
Moderate

279 interactions

Showing 60 of 279 moderate interactions — see all 279 on the English Ivy page.

No interaction 2,550 drugs checked — show the list

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

Showing the 60 most looked-up of 2,550 medications checked with no known interaction — see the full English Ivy list.

See the full English Ivy 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
English Ivy 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 English Ivy and Warfarin Together: Common Questions

Can you take English Ivy with Warfarin?
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.
Why are there 2 interactions listed for English Ivy and Warfarin?
Warfarin belongs to more than one drug category, and English Ivy interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the English Ivy and Warfarin 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 and English Ivy?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.