What are the benefits of glycolic acid?

Thanks to its low molecular weight, glycolic acid has an excellent ability to penetrate the skin. Its main action is keratolytic, meaning that it breaks the bonds between corneocytes, the dead cells of the stratum corneum, thereby facilitating their removal. By clearing the pores of accumulated cellular debris, it helps to prevent the formation of comedones and blemishes more generally. In addition, by accelerating cell turnover, glycolic acid helps to smooth surface irregularities, resulting in a more refined skin texture.

Several scientific studies have sought to evaluate the effectiveness of glycolic acid on acne-prone skin. In a double-blind clinical trial involving 26 patients with acne, participants applied a 40% peel to one half of their face and a placebo solution to the other half. After five sessions carried out at two-week intervals, the results showed a statistically significant reduction in acne lesions on the half of the face treated with glycolic acid compared with the placebo side. The study highlighted that this active ingredient was particularly effective on non-inflammatory lesions, such as blackheads, and that it led to a marked decrease in sebum secretion from the eighth week of treatment onwards.

Glycolic acid is one of the benchmark active ingredients for targeting skin imperfections.

The action of glycolic acid on dark spots is also based on its exfoliating capacity. By breaking down desmosomes, the “bridges” that hold corneocytes together, it promotes the removal of melanin-loaded cells that have accumulated at the surface of the epidermis. This accelerated cell turnover helps to “bring up” the healthy skin layers and even out the distribution of pigments. In addition, it helps to smooth the stratum corneum, which then reflects light more effectively.

Glycolic acid acts against both pigment spots and dull complexion.

The efficacy of this active ingredient was assessed in a comparative study against another reference depigmenting agent: azelaic acid. A study conducted on 40 patients with hyperpigmentation compared the daily use of a cream containing 12% glycolic acid with a cream containing 10% azelaic acid over a twelve‑week period. The results indicate that although azelaic acid shows visible effects more rapidly (from the fourth week), glycolic acid provides a significant improvement from the eighth week of treatment. By the end of the study, both active ingredients were considered to be equally effective in reducing the appearance of pigmented spots.

Thanks to its exfoliating properties, glycolic acid is an ally in restoring an even complexion and radiant skin.

Glycolic acid is a reference active ingredient for correcting the signs of photoageing thanks to its dual epidermal and dermal action. In addition to stimulating epidermal renewal, glycolic acid stimulates fibroblast activity to boost the production of collagen and glycosaminoglycans, such as hyaluronic acid. By densifying the extracellular matrix, glycolic acid restores the skin’s elasticity and firmness and helps to progressively fill in wrinkles. A study carried out on human skin explants specifically highlighted these mechanisms. After five days of applying creams containing between 8 and 25% glycolic acid, the researchers observed an increase in cell proliferation in the epidermis, as well as a significant rise in collagen levels.

These effects observed in the laboratory have also been confirmed by clinical assessments in volunteers. A double-blind, placebo-controlled study was conducted on 41 participants to evaluate the impact of a 50% glycolic acid peel on photoageing. Participants received a weekly application for 4 weeks on one half of the face, the forearms and the hands. The results revealed a significant improvement in skin texture and a reduction in fine lines, as well as a lightening of age spots. From a histological perspective, biopsies confirmed a thinning of the stratum corneum together with a thickening of the epidermis and, for several volunteers, an increase in collagen thickness in the dermis.

The application of glycolic acid peels not only produces an immediate visible improvement in the skin, but also induces a deep restructuring of the tissues to counteract the effects of photoageing.

While glycolic acid is often associated with exfoliation, its action also contributes to the long‑term resilience of the skin. By stimulating cellular metabolism, it induces a thickening of the epidermis, thereby increasing the skin’s natural protection. This process is accompanied by an increased synthesis of glycosaminoglycans and hyaluronic acid, sponge‑like molecules capable of retaining water within the tissues. This hydration, combined with a stronger epidermal structure, optimises the skin’s barrier function, making it better able to defend itself against external aggressions and to reduce transepidermal water loss.

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