Drug & supplement interaction

Horse Chestnut + Pentoxifylline

Pentoxifylline brand name: Trental.

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

Horse Chestnut has a moderate interaction with Pentoxifylline. Horse chestnut may have antiplatelet effects and may increase the risk of bleeding if 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

Horse Chestnut and Pentoxifylline

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

Moderate

ANTICOAGULANT/ANTIPLATELET DRUGS

Why this applies to Pentoxifylline

Pentoxifylline falls under ANTICOAGULANT/ANTIPLATELET DRUGS — the group Horse Chestnut interacts with.

Horse chestnut may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
Horse chestnut contains the constituent esculin which has been shown to have antithrombotic effects. Therefore, horse chestnut might have antiplatelet effects. This has not been shown 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 thing with these two: pentoxifylline already works by thinning your blood a little so it flows more easily through small vessels, and it has mild antiplatelet (anti-clotting) activity of its own. Horse chestnut may add a small blood-thinning push on top of that, mostly from a compound called esculin. Stacked together, the theoretical worry is a slightly higher chance of bleeding or bruising.

I want to be honest about how soft this evidence is. The antiplatelet effect of horse chestnut has only been seen in lab settings, not in actual people, so this is a 'just in case' caution rather than a proven problem. Still, watch for easy bruising, nosebleeds, bleeding gums, or any unusual bleeding, and check with your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. 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

Horse Chestnut Also Interacts With Other Medications

Horse Chestnut has 121 moderate known drug interactions in our database — the Pentoxifylline 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. Pentoxifylline)
Taking anything else?

Check Another of Your Medications Against Horse Chestnut

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

From our Q&A

Questions About Horse Chestnut or Pentoxifylline

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

This page covers Horse Chestnut only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Pentoxifylline page lists 218 supplements it has a documented interaction with, worst first, each one explained.

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

By severity: 3 major · 190 moderate · 25 minor.

From our pharmacist’s overview on the Pentoxifylline page

“Pentoxifylline (Trental) improves blood flow in people with poor leg circulation partly by making platelets less sticky, so treat this list as one to read carefully rather than skim. Of the 218 supplements on file, 202 can also slow clotting, which means adding them stacks bleeding risk on bleeding risk.”

Reviewed by 2 · Jul 18, 2026

Open the Pentoxifylline interaction page

One more smart check

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

We hold 487 real supplement products containing Horse Chestnut, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Horse Chestnut. Your product may carry other ingredients that interact with Pentoxifylline too, on top of Horse Chestnut — 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 Horse Chestnut and Pentoxifylline 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 Horse Chestnut
Top 25%

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

29 days ago today
Medication Pentoxifylline
Top half

#862 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 Horse Chestnut

What is Horse Chestnut?

  • Chronic venous insufficiency
  • Leg swelling and heaviness
  • Varicose veins
  • Hemorrhoids
  • Bruising and minor swelling

Horse chestnut seed extract is most often used for chronic venous insufficiency, where standardized products may help reduce leg swelling, pain, and heaviness. Raw, unprocessed horse chestnut seeds and other parts of the plant are toxic and should never be eaten. Talk with your pharmacist or doctor before using it, and avoid it during pregnancy and breastfeeding.

Read the full Horse Chestnut monograph & all interactions
Medication

About Pentoxifylline

What Is Pentoxifylline Used For?

Brand name: Trental

Pentoxifylline Extended-Release Tablets are used to treat intermittent claudication — leg pain, cramping, or fatigue that happens during walking because narrowed arteries aren't delivering enough blood to the muscles. The underlying cause is chronic occlusive arterial disease, a condition where the arteries in the limbs become blocked or narrowed over time.

Pentoxifylline can help improve walking distance and reduce symptoms, but it is not a substitute for procedures that physically open or bypass blocked arteries when those treatments are needed.

See full Pentoxifylline drug information
Keep checking

Other Drugs & Horse Chestnut

Browse every other medication we’ve checked against Horse Chestnut — 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 Horse Chestnut page.

No interaction 2,708 drugs checked — show the list

We also checked Horse Chestnut 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 Horse Chestnut list.

See the full Horse Chestnut interactions page
See every supplement checked against Pentoxifylline, 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
Horse Chestnut monograph › Uses, safety, and every drug interaction in one place Pentoxifylline supplement interactions › Every supplement checked against Pentoxifylline, ranked by severity Pentoxifylline 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 Horse Chestnut and Pentoxifylline Together: Common Questions

Can you take Horse Chestnut with Pentoxifylline?
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 Horse Chestnut and Pentoxifylline 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 Pentoxifylline and Horse Chestnut?

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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.