Drug & supplement interaction

L-carnitine + Acenocoumarol

Acenocoumarol brand name: Sintrom.

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

L-carnitine has a moderate interaction with Acenocoumarol. Theoretically, L-carnitine might increase the anticoagulant effects of acenocoumarol.

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

L-carnitine and Acenocoumarol

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

Moderate

ACENOCOUMAROL (Sintrom)

Theoretically, L-carnitine might increase the anticoagulant effects of acenocoumarol.
L-carnitine might enhance the anticoagulant effects of acenocoumarol, an oral anticoagulant similar to warfarin, but shorter-acting. There are at least two case reports of INR elevation with concomitant use. In one case, a 33-year-old male with a previously stable INR had an elevated INR of 4.65 after L-carnitine was started and continued for 10 weeks. INR normalized after discontinuation of the L-carnitine-containing product.
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 if you take acenocoumarol (Sintrom) and are thinking about an L-carnitine supplement. Sintrom is a blood thinner, and a few case reports suggest that adding L-carnitine may strengthen its effect, meaning your blood could become a bit thinner than your dose intends. In one report, a man with a steady INR saw it climb to 4.65 after starting L-carnitine, then settle back down once he stopped.

Sintrom is a narrow-therapeutic-index drug, so even small shifts matter. A stronger-than-planned effect can show up as easy bruising, nosebleeds, bleeding gums, or blood in the urine or stool. Honestly, the evidence here is thin and theoretical, not proven. Still, please don't start or stop anything on your own. Talk with your pharmacist or doctor first, and they can check your INR if needed.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Martinez E, Domingo P, Roca-Cusachs A. Potentiation of acenocoumarol action by L-carnitine. J Intern Med 1993;233:94.
  2. Bachmann HU, Hoffmann A. Interaction of food supplement L-carnitine with oral anticoagulant acenocoumarol. Swiss Med Wkly 2004;134:385. 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

L-carnitine Also Interacts With Other Medications

L-carnitine has 18 moderate known drug interactions in our database — the Acenocoumarol one above is one of them. If you take anything else, check it against the full list below.

Moderate 18 No known interaction 2,812 (incl. Acenocoumarol)
Taking anything else?

Check Another of Your Medications Against L-carnitine

Covers the 2,830 medications we’ve checked against L-carnitine. Pick one to open its full report.

From our Q&A

Questions About L-carnitine or Acenocoumarol

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers L-carnitine or Acenocoumarol, 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 Acenocoumarol

This page covers L-carnitine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Acenocoumarol page lists 221 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), Acetyl-l-carnitine (moderate) and Aconite (moderate).

By severity: 3 major · 193 moderate · 25 minor.

From our pharmacist’s overview on the Acenocoumarol page

“Acenocoumarol (Sintrom) is a blood thinner in the warfarin family, and it lives in a narrow zone where a little too much means bleeding and a little too little means clots. So treat its 221 supplement interactions as a real safety issue, not fine print.”

Reviewed by 2 · Jul 18, 2026

Open the Acenocoumarol interaction page

One more smart check

Taking L-carnitine as Part of a Dietary Supplement Product? Check It for Interactions

We hold 3,350 real supplement products containing L-carnitine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides L-carnitine. Your product may carry other ingredients that interact with Acenocoumarol too, on top of L-carnitine — 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 L-carnitine and Acenocoumarol 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 L-carnitine
Top 10%

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

29 days ago today
Medication Acenocoumarol
Top 10%

#234 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 L-carnitine

What is L-carnitine?

  • Exercise performance and recovery
  • Heart health
  • Weight management
  • Energy and fatigue
  • Male fertility
  • Carnitine deficiency

L-carnitine is a compound your body makes naturally and also gets from foods like meat. It helps cells turn fat into energy, and supplements are most clearly useful for people with a true carnitine deficiency. For most other uses, like weight loss or boosting athletic performance, the evidence is mixed or limited, so talk with your pharmacist or doctor before trying it.

Read the full L-carnitine monograph & all interactions
Keep checking

Other Drugs & L-carnitine

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

0Major
18Moderate
0Minor
2,811No known interaction
18 Moderate 2,811 No interaction
Moderate

18 interactions

No interaction 2,811 drugs checked — show the list

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

Showing the 60 most looked-up of 2,811 medications checked with no known interaction — see the full L-carnitine list.

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

Can you take L-carnitine with Acenocoumarol?
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 L-carnitine and Acenocoumarol 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 Acenocoumarol and L-carnitine?

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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.