L-carnitine: what are its benefits for the skin?

The L-carnitine is part of the new generation of active ingredients of interest for oily skin due to its role in cellular energy metabolism. This molecule acts as a transporter for long-chain fatty acids, shuttling them to the mitochondria for oxidation and energy production. In sebaceous glands, a significant portion of sebum production relies on the availability of these fatty acids. By enhancing their mitochondrial utilization, L-carnitine could limit the intracellular lipid reserve, thereby reducing sebum synthesis.

A study in vitro conducted on a human sebaceous cell line (SZ95) demonstrated the benefits of L-carnitine for oily skin. When these cells were exposed to concentrations of 0.5% and 1% of L-carnitine, they showed a significant increase in β-oxidation, that is, the process of degrading fatty acids by the mitochondria. In parallel, the amount of intracellular lipids decreased in a dose-dependent manner, indicating a reduced pool available for sebum synthesis. Beyond these results in vitro, several clinical studies have also highlighted the benefits of L-carnitine for oily skin.

The ability of L-carnitine to reduce sebum production makes it of particular interest in acne management. Indeed, excess sebum is one of the key factors in this condition, as it promotes the obstruction of pilosebaceous follicles and the proliferation of Cutibacterium acnes, a bacterium involved in the development of inflammatory lesions. By regulating the availability of intracellular fatty acids and thus the amount of sebum produced, L-carnitine could limit comedone formation and reduce the severity of acne flare-ups.

A clinical study explored this effect by evaluating an original therapeutic combination in 29 volunteers with mild to severe acne. The protocol consisted of using photodynamic therapy (PDT, via intense pulsed light at 400–720 nm, administered in four sessions spaced two weeks apart), combined with a cream containing L-carnitine, licochalcone A, and decanediol, applied twice daily for 10 weeks. The other side received the same protocol but with a placebo cream. The results showed a faster and more effective reduction in lesion count in the “L-carnitine” group. However, it is important to emphasize that these results cannot be attributed to L-carnitine alone: the observed efficacy relies on a cream combining multiple actives (L-carnitine, licochalcone A, and decanediol) and on its use in conjunction with photodynamic therapy.

The L-carnitine could also be of interest in combating skin aging. Indeed, it has antioxidant properties that enable it to neutralize free radicals generated notably by UV radiation, which are responsible for collagen and elastin breakdown. At the same time, studies in vitro have shown that L-carnitine inhibits the activity of matrix metalloproteinases MMP-1 and MMP-2, enzymes that contribute to the degradation of the dermal matrix under oxidative stress. By combining these two actions, L-carnitine thus helps preserve skin elasticity and firmness.

Good to know : The antioxidant properties of L-carnitine may also help promote a more radiant complexion.

These hypotheses were confirmed in a clinical study conducted on 50 women, divided into two groups: one using a cream containing 1% L-carnitine and the other a placebo. After 12 weeks of twice-daily application over the entire face, evaluation by visiometry revealed a significant reduction in two skin-roughness parameters (R2 and R3) among the women in the L-carnitine group, reflecting a visible improvement in skin texture and a decrease in wrinkles compared with the placebo. No adverse effects were reported, confirming the compound’s good tolerability. These results suggest that L-carnitine may play an interesting role in the prevention and mitigation of skin aging.

Pruritus is a common symptom seen in numerous situations. It may occur sporadically, for example after an insect bite, or persist in a chronic context, such as in the case of eczema. These itching sensations, often trivialized, nonetheless impair quality of life and reflect inflammatory and oxidative imbalances in the skin.

In this context, L-carnitine has demonstrated anti-inflammatory and anti-pruritic properties of interest. An experimental study evaluated its effects in a mouse model of chloroquine-induced itch. The results showed that oral administration of L-carnitine significantly reduced scratching behavior compared to the control group, confirming its antipruritic potential. On a biological level, the molecule restored the balance of antioxidant defenses (GST, GSH, and catalase) while reducing lipid peroxidation (LPO). It also decreased nitric oxide synthase (NOS) activity, thus modulating the nitric oxide pathway involved in itch genesis. Finally, L-carnitine reduced levels of pro-inflammatory cytokines (TNF-α), pro-inflammatory enzymes such as COX-2, and the p-NFκB marker. Together, these effects suggest that L-carnitine acts both by limiting inflammation and by regulating oxidative stress, thereby contributing to itch relief.

However, caution is warranted, as this study was conducted in mice and relied on oral administration of L-carnitine, which limits extrapolation.

Moreover, other studies have reported an interest in the L-carnitine in topical application to soothe eczema, but these studies combined the molecule with other actives whose efficacy against eczema is already well documented. It therefore remains difficult to determine to what extent L-carnitine alone truly contributes to symptom improvement.

The wound healing process is a complex sequence that relies on several phases: the initial inflammatory phase, fibroblast proliferation, collagen synthesis, and finally re-epithelialization. Any disruption of this process can result in delayed healing, persistent skin fragility, or hypertrophic scarring. Several active ingredients can support this process, potentially including L-carnitine.

An experimental study conducted on 60 rats evaluated the effects of L-carnitine on skin wound healing. The animals were divided into three groups: a control group without treatment, a group receiving a local administration of L-carnitine, and a group receiving a systemic administration, all monitored for 14 days. The researchers analyzed the rate of wound closure, the quality of the repaired tissue, and the mechanical strength of the wounds. They observed that the average healing time was significantly reduced in the groups using L-carnitine, whether taken orally or applied topically. Moreover, the treated rats exhibited a faster re-epithelialization and increased collagen deposition.

However, since these data are derived from an animal model, it remains necessary to confirm these effects in humans before considering a clinical application.

When applied topically, L-carnitine is thought to enhance fat breakdown by facilitating the uptake of fatty acids into adipocyte mitochondria via the enzymatic carnitine–palmitoyl transferase 1 (CPT1) complex. This enables acyl-carnitine formation, which crosses the mitochondrial membrane and is then converted back into acyl-CoA, thereby initiating β-oxidation. This mechanism leads to a reduction in adipocyte volume, which could alleviate the lipid overload observed in cellulite. At the same time, L-carnitine also appears to modulate oxidative stress, a factor that exacerbates fibrosis and inflammation in skin tissue. By reducing lipid peroxidation and protecting collagen and elastin fibers, it may help preserve connective tissue integrity.

A clinical trial explored this hypothesis by testing a cream containing L-carnitine and caffeine, applied daily for 28 days in seven participants who also followed a hypocaloric diet and a weekly walking program. Compared with placebo, the tested formulation produced a more pronounced reduction in thigh circumference and in fat mass as measured by dual-energy X-ray absorptiometry.

These results suggest a potential role for L-carnitine in improving cellulite, but their scope is limited by the small number of participants and the presence of other known lipolytic agents. Thus, it is difficult to attribute the observed effect solely to L-carnitine, and larger-scale studies are still needed to confirm its actual efficacy.

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