L-carnitine: what are its modes of use?

Topical application of L-carnitine: for a direct action on the skin.

The first way to use L-carnitine is via topical application. In the form of creams, serums or gels, this active ingredient penetrates the skin relatively well thanks to its small molecular size and offers it several benefits. One of the most studied effects of the L-carnitine concerns the regulation of sebum production. By stimulating the oxidation of free fatty acids in the sebaceous glands, it reduces skin shine, the risk of pore blockage and the emergence of blemishes. This sebum-regulating effect explains why L-carnitine is frequently used in treatments for combination to oily skin. Beyond this sebum-regulating action, L-carnitine may also help target mild to moderate acne. By limiting sebum production, it creates a skin environment less favourable to the proliferation of Cutibacterium acnes, a bacterium that exacerbates acne.

The L-carnitine could also be of interest for reducing wrinkles, notably by neutralising the free radicals produced during energy metabolism and under UV exposure. Another area where the L-carnitine appears promising: skin healing. By accelerating cell turnover and reducing inflammation, L-carnitine promotes faster repair of skin lesions, whether related to blemishes, minor cosmetic procedures or irritation.

Topical application of L-carnitine is often well tolerated, with little risk of irritation.

This active ingredient can be used morning and evening and poses no risk of photosensitisation. Most products containing L-carnitine are dosed at concentrations ranging from 2% to 5%, although European regulations do not set a maximum concentration.

Note : The L-carnitine can also be used to care for the scalp and hair, certain studies in vitro have furthermore shown that it can support hair growth.

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Oral intake of L-carnitine: metabolic support for indirect effects on the skin.

Oral supplementation with L-carnitine, particularly in the form of dietary supplements, has been primarily studied for its effects on metabolism and body composition. Several clinical trials have shown that a regular course can help reduce body mass index (BMI) and body fat. By promoting the transport of fatty acids into the mitochondria, where they are used as an energy source, L-carnitine optimises lipid oxidation and contributes to a more efficient metabolism. This active compound is therefore highly valued by individuals seeking a slimmer silhouette, even though its efficacy remains variable from one person to another. Furthermore, L-carnitine appears capable of lowering total cholesterol levels, triglycerides and LDL, that is the “bad” cholesterol, while raising HDL, the “good” cholesterol.

Moreover, oral supplementation with L-carnitine may support skin health and slow certain mechanisms involved in skin ageing. Animal studies show that it limits UVA-induced damage, especially by reducing oxidative stress, inflammation and DNA alterations. These protective effects could contribute to preserving skin elasticity and delaying the appearance of wrinkles. Nevertheless, since these effects have been demonstrated only in murine models, caution is warranted.

How should L-carnitine be taken orally?

L-carnitine is readily available in capsule or tablet form. The dosages most commonly employed in clinical studies range from 500 mg to 2 g per day, divided into one or two administrations. Researchers recommend taking L-carnitine with meals to optimise its absorption and utilisation by the body. Some individuals also opt for liquid formulations, but L-carnitine capsules and tablets remain the most popular.

In practice, L-carnitine is taken in the form of a 4- to 12-week course. As with any dietary supplement, it is essential to follow the dosage instructions on the packaging and to consult a healthcare professional before starting, especially in the event of chronic illness or concurrent medication use.

L-carnitine injections: a more targeted medical approach.

Finally, L-carnitine can be administered as an injectable solution, either intramuscularly or intravenously. In theory, this ensures immediate bioavailability, as the substance can directly enter the bloodstream. In practice, this route of administration is reserved for the hospital setting, particularly in certain medical indications related to metabolic disorders or carnitine deficiencies. They require strict physician supervision to ensure safety and efficacy.

Although their aesthetic application is sometimes mentioned, scientific evidence remains insufficient to confirm a direct effect on reducing cellulite or improving skin tone. In sports, some athletes use L-carnitine injections to stimulate fat oxidation and enhance their energy performance. However, this practice remains controversial, as the actual benefits are still debated and the associated risks should not be underestimated.