L-carnitine is not confined to its applications in nutrition and sport. It is increasingly investigated in dermatology, and some credit it with the ability to strengthen hair anchoring and prevent hair loss. Myth or reality? Find out here whether the scientific literature supports this hypothesis.
L-carnitine, an ally for protecting hair against hair loss?
Published on October 1, 2025, updated on October 1, 2025, by Jamal, PhD, Doctor of human pathology and infectious diseases — 7 min of reading
Themes:
L-carnitine, a solution for hair loss?
Losing hair is a natural phenomenon: each day, it is normal to see between 50 and 100 hairs shed. This renewal is part of the hair follicle’s life cycle, which alternates between growth, rest and shedding phases. However, sometimes the hair loss can intensify and become more visible, causing concern and prompting the search for solutions. The causes are varied: heredity, hormonal fluctuations, stress, an unbalanced diet or skin ageing. If the hair loss is rarely a sign of a serious condition, it can significantly impact self-esteem and quality of life. This is why many people look for solutions to strengthen their hair and protect it from shedding, such as L-carnitine.
Several recent studies have examined the role of L-carnitine in stimulating hair growth. An in vitro study assessed the effect of L-carnitine-L-tartrate (referred to as CT in the study) on human hair follicles in the anagen phase, the active growth phase of hair. The follicles were cultured for 9 days with varying CT concentrations (0.5 to 50 µM). The results showed that follicles treated with moderate concentrations (0.5 and 5 µM) exhibited a significant stimulation of hair shaft elongation, with a 37% increase in hair length compared to the control group.
Hair shaft elongation in millimetres (a) and as a percentage (b) following treatment of hair follicles with different concentrations of L-carnitine-L-tartrate.
Source: PAUS R. & al. L-carnitine-L-tartrate promotes human hair growth in vitro. Experimental Dermatology (2007).
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The study also demonstrated that L-carnitine acts directly on hair follicle keratinocytes by promoting their proliferation and inhibiting their apoptosis, that is, their programmed cell death. Histological analyses revealed a significant decrease in apoptotic cells and a slight increase in proliferative cells within the hair matrix of treated follicles. This cellular modulation prolongs the anagen phase, allowing more sustained hair growth. These initial results in vitro, to be confirmed in clinical trials, justify the interest in L-carnitine for topical application or oral intake to strengthen the hair.
Research into L-carnitine is not limited to this single study in vitro. A nine-month clinical trial assessed the efficacy of L-carnitine in reducing hair loss and improving scalp health. Four groups of 20 participants each were formed: the first received an oral L-carnitine supplement, the second applied a topical lotion containing L-carnitine, the third combined both supplement and lotion, and the fourth served as an untreated control group. In total, 79 participants completed the trial.
| Active | Oral supplement | Topical lotion |
|---|---|---|
| L-carnitine | 544 mg | Present (> 2%) |
| L-leucine | 150 mg | Present |
| L-isoleucine | 75 mg | Present |
| L-valine | 75 mg | Present |
| Potassium | 100 mg | Present |
| Nicotinamide | 40 mg | Present |
| Zinc | 15 mg | Present |
| Biotin | 150 µg | Present |
| Selenium | 75 µg | Absent |
| Methylsulfonylmethane (MSM) | Absent | Present |
Composition of the oral supplement and topical lotion.
Source: BAYER M. & al. The effect of a food supplement and a hair lotion on the progression of androgenetic alopecia. Journal of Cosmetics, Dermatological Sciences and Applications (2019).
After nine months, all treated groups demonstrated a significant reduction in hair loss, unlike the control group, which recorded an average 23.7% increase in shedding. Mean reductions in the treated groups were −35.4% for the supplement, −38.8% for the lotion and −31.0% for the supplement–lotion combination. Furthermore, 75% of participants in the treated groups reported reduced shedding, and 67% perceived their hair as healthier by the end of the study.
The study also demonstrated that L-carnitine–based products increased the ratio of hairs in the anagen phase (growth phase) to those in the telogen phase (shedding phase). The treated groups exhibited an average improvement in this ratio of +55.1% (supplement), +39.4% (lotion) and +63.5% (combination), whereas the control group experienced a slight decrease of −3.9%. No adverse effects were observed, confirming the good tolerability of the formulations.
Effects of oral, topical or combined L-carnitine supplementation on hair loss (a) and the ratio between anagen-phase and telogen-phase hairs (b).
Source: BAYER M. et al. The effect of a dietary supplement and a hair lotion on the progression of androgenetic alopecia. Journal of Cosmetics, Dermatological Sciences and Applications (2019).
The results obtained with L-carnitine are encouraging and suggest that it could help to combat hair loss.
However, as the clinical trial combines several active compounds with complementary properties, it is difficult to attribute the observed benefits specifically to L-carnitine. It is therefore necessary to proceed with caution and to pursue research through larger-scale clinical studies that further isolate the effect of L-carnitine, in order to confirm its potential benefit in cases of hair loss.
Sources
PAUS R. & al. L-carnitine-L-tartrate promotes human hair growth in vitro. Experimental Dermatology (2007).
PEDRE-PINEIRO A. M. & al. Significance of L-carnitine for human health. IUBMB Life (2017).
BAYER M. & al. The effect of a food supplement and a hair lotion on the progression of androgenetic alopecia. Journal of Cosmetics, Dermatological Sciences and Applications (2019).
CONSOLARO F. & al. A liposome-based formulation containing equol, dihomo-γ-linolenic acid and propionyl-L-carnitine to prevent and treat hair loss: A prospective investigation. Dermatologic Therapy (2019).
ASBAGHI O. & al. The effects of L-carnitine supplementation on inflammatory and anti-inflammatory markers in adults: A systematic review and dose-response meta-analysis. Inflammopharmacology (2023).
