Written by Peter Renner, Markus Horneber and the CAM-Cancer Consortium.
Updated January 29, 2015


Is it safe?

The use of LC is regarded as ‘Likely safe when used orally and appropriately and when used parenterally as an FDA-approved prescription medicine’.46 Oral LC has been used safely in children for up to 2 months and intravenously in preterm infants. For pregnant women, there is insufficient reliable information available to date. Although LC is secreted in breast milk, use during breast-feeding is regarded as safe because supplemental doses of LC have been administered to children in formula diets with no reported adverse effects.46 Clinical trials lasting from four weeks to six months have used amounts  of LC from under 1g up to 6g per day without any apparent ill effects.

Adverse effects

In the studies discussed above, LC used orally or intravenously has been less frequently associated with nausea, insomnia, vomiting and gastrointestinal upset of minor intensity.


Patients using thyroid medications should not take LC unless supervised by a physician. Individuals with low or borderline-low thyroid levels should avoid taking supplemental LC because it might impair the action of thyroid hormones.47


It has been observed that long-term treatment with ementine, pivalic acid and the anticonvulsant valproic acid leads to secondary carnitine deficiency. Histological findings of an animal study in mice with Ehrlich tumour indicate that combining ALC with mitoxantrone might be inappropriate.48

Quality issues

Supplements containing D-carnitine or dl-racemates should be avoided because D-carnitine can interfere with LC membrane transport, thus increasing the risk of LC deficiency.49, 50

Citation Peter Renner, Markus Horneber, CAM-Cancer Consortium. L-Carnitine [online document]. http://ws.cam-cancer.org/The-Summaries/Dietary-approaches/L-Carnitine. January 29, 2015.


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