The effects of hyaluronic acid on brown spots?

The brown spots, or hyperpigmentation marks, correspond to areas of the epidermis affected by an overproduction of melanin and can impact the uniformity of the complexion. Although they can occur in all skin tones, they are generally more common in darker phototypes (IV to VI) and tend to appear around the ages of 40-50. Most frequently, pigmentation spots result from repeated and prolonged exposure to the sun throughout life. Hormonal variations, particularly in pregnant women, can also cause hyperpigmentation: this is the well-known pregnancy mask. Finally, increased activity of melanocytes stimulated by pro-inflammatory cytokines can also cause brown spots. This is then referred to as post-inflammatory hyperpigmentation.

While certain actives can act against hyperpigmentation and reduce it, there is currently very little scientific evidence to suggest that this is the case for hyaluronic acid, whose cosmetic power lies mainly in its ability to absorb and retain water. As for its potential depigmenting effects, these have not been the subject of any clinical trials. Only one study, conducted very recently in vitro on human skin explants, has looked into this. For this, a molecular complex composed of high molecular weight hyaluronic acid, amino acids (cysteine, glycine, lysine, proline and valine) oligopeptides (glutathione), vitamin C and biotin was tested.

This complex was administered to certain skin explants and the percentage of cells exhibiting low, medium, and high levels of melanin was assessed as an indicator of the degree of pigmentation. The results obtained are recorded in the table below and demonstrate a depigmenting action of the complex.

Under physiological conditions, melanocytes, which are the cells that produce melanin, are surrounded by a layer of hyaluronic acid. This layer prevents them from synthesising and secreting cytokines and chemokines. Ultraviolet rays promote the breakdown of hyaluronic acid by hyaluronidases and the secretion of these pro-inflammatory factors by melanocytes. These factors, particularly cytokines, play a crucial role in the manifestation of pigmentation disorders. Therefore, it could be hypothesised that hyaluronic acid has a certain protective effect on melanocytes, and, by extension, contributes to the prevention of hyperpigmentation.

However, caution should be exercised regarding its potential corrective action on brown spots. Indeed, the study mentioned was conducted in vitro and hyaluronic acid was only one of the components of the complex. Other studies have shown a glutathione anti-melanogenic effect, a molecule that notably interferes with the formation of pheomelanin. Vitamin C also has a brightening effect on the complexion, via its anti-tyrosinase effect.

Thus, there is currently not enough evidence to assert that hyaluronic acid has an effect on brown spots.

Tip : If you wish to reduce your hyperpigmentation marks, we would advise you to rely on the alpha-arbutin acid, the retinol, or even the glycolic acid. Laser sessions, carried out by a professional you trust, are also a solution.

• ANDRE P. Hyaluronic Acid and Its Application as a "Rejuvenation" Agent in Cosmetic Dermatology. Seminars in cutaneous medicine and surgery (2004).

• BONIFACE K. & al. The melanocyte: a major player in the epidermal inflammatory response induced by cutaneous T lymphocytes during vitiligo. Annals of Dermatology and Venereology (2020).

• VERDU E. & al. Anti-Ageing and Depigmentation Impact of a Mechanically Stabilised Hyaluronic Acid Complex on Human Skin Explants. Polymers (2023).