Drug interactions
L-carnitine + Warfarin
Severity: Moderate
L-carnitine and Warfarin: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Case reports describe an increased INR in patients on warfarin who started levocarnitine. The effect is inconsistent but could raise bleeding risk in patients with a narrow therapeutic margin.
What this interaction means in plain words
L-carnitine and Warfarin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
L-carnitine belongs to Gastrointestinal Tract; Warfarin belongs to Cardiovascular.
Why it happens
Mechanism is unknown.
What to do
Check the INR within about a week of starting or stopping levocarnitine and adjust the warfarin dose to the target range.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of L-carnitine
- L-carnitine + Valproic acid Moderate
- Carbamazepine + L-carnitine Minor
- Fosphenytoin + L-carnitine Minor
- L-carnitine + Phenobarbital Minor
- L-carnitine + Phenytoin Minor
- L-carnitine + Primidone Minor
Other interactions of Warfarin
- Defibrotide + Warfarin Contraindicated
- Ketorolac + Warfarin Contraindicated
- Abciximab + Warfarin Major
- Acetylsalicylic acid + Warfarin Major
- Adagrasib + Warfarin Major
- Amiodarone + Warfarin Major
Frequently asked questions
Can I take L-carnitine with Warfarin?
MediHelp rates the interaction as moderate. L-carnitine and Warfarin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Case reports describe an increased INR in patients on warfarin who started levocarnitine. The effect is inconsistent but could raise bleeding risk in patients with a narrow therapeutic margin.
How serious is the interaction between L-carnitine and Warfarin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check the INR within about a week of starting or stopping levocarnitine and adjust the warfarin dose to the target range.
What other medicines interact with L-carnitine?
MediHelp also lists interactions of L-carnitine with, for example, Valproic acid, Carbamazepine, Fosphenytoin. The full list is on the L-carnitine page.
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