Amino acids

L-carnitine

Also called: carnitine, acetyl-L-carnitine, ALCAR, carnitine tartrate

A compound that carries fats into cells to be burned for energy.

Why people take it
Weight loss, energy, exercise, memory (acetyl-L-carnitine).
What the evidence says
Small weight loss in some studies. Acetyl-L-carnitine may help some nerve pain.
How it is usually taken
Usually 500 mg to 2 g a day; acetyl-L-carnitine for nerve pain studies.
Be careful
Fishy body odour and stomach upset. Raises TMAO, which may be linked to heart disease; may affect thyroid medicine.
Medicines it can interact with
May increase the effect of warfarin and reduce the effect of thyroid hormone.

Other amino acids

L-arginineL-citrullineL-glutamineBeta-alanineBCAAsEAAsL-tyrosineL-lysineGlycineTaurineN-acetylcysteine (NAC)Glutathione5-HTPL-tryptophanGABASAMe

Common questions

What is L-carnitine?

A compound that carries fats into cells to be burned for energy.

Why do people take L-carnitine?

Weight loss, energy, exercise, memory (acetyl-L-carnitine).

Does L-carnitine work?

Small weight loss in some studies. Acetyl-L-carnitine may help some nerve pain.

How much L-carnitine do people take?

Usually 500 mg to 2 g a day; acetyl-L-carnitine for nerve pain studies.

Is L-carnitine safe?

Fishy body odour and stomach upset. Raises TMAO, which may be linked to heart disease; may affect thyroid medicine.

Does L-carnitine interact with medicines?

May increase the effect of warfarin and reduce the effect of thyroid hormone.

Sources and further reading

Last reviewed 31 October 2026. Written by Satya Babu.

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For information only, not medical advice. Supplements are not medicines: they are not tested and approved like drugs before they are sold, and they can interact with medicines. Talk to your doctor or pharmacist before you start one, especially if you are pregnant or breastfeeding, take regular medicines, or have kidney, liver or heart disease.