L-carnitine: what are its modes of use?

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

The first way to use L-carnitine is through topical application. In cream, serum, or gel forms, this active ingredient penetrates the skin relatively well thanks to its small molecular size and provides several benefits. One of the most studied effects of the L-carnitine involves the regulation of sebum production. By stimulating the oxidation of free fatty acids in the sebaceous glands, it reduces skin shine, pore-clogging risks, and the occurrence of blemishes. This sebum-regulating effect explains why L-carnitine is frequently used in treatments for combination to oily skin. Beyond this sebo-regulatory action, L-carnitine may also help target mild to moderate acne. By limiting sebum production, it creates a skin environment less conducive to the proliferation of Cutibacterium acnes, a bacterium that worsens acne.

The L-carnitine may also be beneficial for smoothing wrinkles, particularly by neutralizing free radicals generated during energy metabolism and from UV exposure. Another field where the L-carnitine appears promising is in skin healing. By accelerating cell turnover and reducing inflammation, L-carnitine promotes faster repair of skin lesions, whether due to blemishes, minor cosmetic procedures, or irritations.

Topical application of L-carnitine is generally well tolerated, with minimal risk of irritation.

This active ingredient can be used morning and night and does not pose a risk of photosensitization. Most products containing L-carnitine are formulated 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, some studies in vitro have shown that it can support hair growth.

4 minutes to understand your skin. Our dermatological diagnostic guides you toward the ideal skincare for your specific needs. Simple, quick, personalized.

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

Oral L-carnitine supplementation, 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 regimen can help reduce body mass index (BMI) and fat mass. By promoting the transport of fatty acids into the mitochondria where they serve as an energy source, L-carnitine enhances lipid oxidation and supports a more efficient metabolism. This compound is therefore highly sought after by individuals aiming for a slimmer physique, although its effectiveness can vary from person to person. Additionally, L-carnitine has been reported to lower total cholesterol, triglycerides, and LDL—commonly known as “bad cholesterol”—while increasing HDL, or “good cholesterol.”

Furthermore, oral L-carnitine supplementation may support skin health and slow certain mechanisms associated with skin aging. Animal studies indicate it limits UVA-induced damage, notably by reducing oxidative stress, inflammation, and DNA alterations. These protective effects could contribute to preserving skin elasticity and delaying the appearance of wrinkles. However, since these effects have been demonstrated in mouse 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 used in clinical studies range from 500 mg to 2 g per day, divided into one to two doses. Researchers recommend taking L-carnitine with meals to optimize its absorption and utilization 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 consult a healthcare professional before starting, especially if you have a chronic condition or are taking medications concurrently.

L-carnitine injections: a more targeted medical approach.

Finally, L-carnitine can be administered as an injectable solution via intramuscular or intravenous routes. In theory, this ensures immediate bioavailability, since the substance can directly enter the bloodstream. In practice, this type of administration is reserved for the hospital setting, particularly in certain medical indications related to metabolic disorders or carnitine deficiencies. They require strict monitoring by a physician to ensure safety and efficacy.

Although their aesthetic use is sometimes mentioned, scientific evidence is still insufficient to confirm a direct effect on cellulite reduction or on improving skin firmness. In sports, some athletes resort to L-carnitine injections to stimulate fat oxidation and enhance their energetic performance. However, this practice remains controversial, as its actual benefits are still under debate and the associated risks are not negligible.