Levocarnitine and Acenocoumarol: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Acenocoumarol
No brand names on recordLevocarnitine
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Increased international normalized ratio and an increased risk of bleeding
Interaction Deep Dive
Gastrointestinal hemorrhage (associated with an elevated international normalized ratio (INR) developed in a 62-year-old woman shortly after adding L-carnitine to her previously stable anticoagulant regimen of acenocoumarol2. In another case report, supratherapeutic INR values were observed in a 33-year-old man after he ingested a nutritional supplement containing levocarnitine while receiving treatment with acenocoumarol 1.
Why it happens (mechanism)
Unknown
Literature reports
2 reports — tap to read
a) A supratherapeutic international normalized ratio (INR) developed in a 33-year-old man treated with acenocoumarol following placement of a St. Jude prosthetic aortic valve. The patient had exhibited stable INR values (1.99 to 2.94) over the year following surgery while receiving a mean dose of acenocoumarol 3.4 milligrams (mg) per day. The patient's INR then increased to 4.65 and persisted despite a correction of acenocoumarol dose. Concurrent with the increase in INR, the patient reported ingesting for 10 weeks a commercial nutritional supplement containing L-carnitine (levocarnitine) 1000 mg/day. The supplement was discontinued, after which the INR decreased to within target range (2.4 to 2.8) and therein remained for over 4 months 1.
b) Gastrointestinal bleeding accompanied by an elevated international normalized ratio (INR) value occurred in a 62-year-old woman after she received concomitant treatment with acenocoumarol and L-carnitine. The patient had been treated with acenocoumarol for 17 years prior to admission and had been on a stable acenocoumarol dose (3 milligrams daily) for the 7 months prior to receiving L-carnitine 1 gram daily for management of congestive heart failure. Five days after beginning L-carnitine therapy, the woman was admitted to the hospital with new onset of melena; INR was 7 at time of admission, and upper and lower GI endoscopy revealed diffuse, superficial bleeding erosive lesions. Acenocoumarol and L-carnitine were stopped and vitamin K was administered. Bleeding resolved on hospital day 4, after which acenocoumarol was restarted and tolerated well at the previous dose (INR of 2.1 on day 10) 2.
Common questions
Can I take Levocarnitine and Acenocoumarol together?
Increased international normalized ratio and an increased risk of bleeding Always confirm with your pharmacist or prescriber before making any change.
How serious is the Levocarnitine and Acenocoumarol interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Levocarnitine or Acenocoumarol need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (2)
- Bachmann HU & Hoffmann A: Interaction of food supplement L-carnitine with oral anticoagulant acenocoumarol. Swiss Med Wkly 2004; 134:385. PubMed
- Martinez E, Domingo P, & Roca-Cusachs A: Potentiation of acenocoumarol action by L-carnitine. J Intern Med 1993; 233(1):94.
Keep reading about Acenocoumarol
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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