How does L-carnitine work?

L-carnitine helps the body produce energy. It is important for heart and brain function, muscle movement, and many other body processes.

Are there safety concerns?

L-carnitine is safe for most people when taken by mouth. It is also safe when used as an injection, with the approval of a healthcare provider. It can cause side effects such as nausea, vomiting, stomach upset, heartburn, diarrhea, and seizures. It can also cause a "fishy" odor of the urine, breath, and sweat.

L-carnitine seems to be safe when used appropriately, short-term in children.

L-carnitine seems safe for most breast-feeding women when taken in the amounts recommended. The effects of large doses taken by a breast-feeding mother are unknown.

Do not take L-carnitine if:
  • You are pregnant.
  • You have seizures or a history of seizures.
  • You have thyroid problems.

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Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.