4 reasons to exfoliate your skin.

At the surface of the epidermis, keratinocytes, the principal cells of the stratum corneum, follow a continuous renewal cycle. As they migrate from the deeper layers to the stratum corneum, these cells differentiate and then undergo apoptosis, a programmed cell death process. Normally, these dead cells are gradually shed through the natural desquamation process, but, over time, the cutaneous ageing, the oxidative stress or certain environmental aggressions, they can accumulate at the surface of the skin. As it becomes thicker, the skin reflects less light, resulting in a dull, fatigued complexion.

The exfoliation precisely triggers this natural elimination mechanism. By clearing the skin of dead cells, it refines skin texture and reveals a brighter complexion. This effect can be achieved through mechanical exfoliation, using formulations containing particles that physically lift corneocytes, or through chemical exfoliation. The latter relies on active ingredients capable of breaking intercellular bonds, particularly those involving glycoproteins within the stratum corneum. By facilitating the detachment of dead cells, exfoliation promotes more uniform cellular renewal, resulting in visibly more radiant and even-toned skin.

The blackheads, also known as open comedones, correspond to obstructions in the pilosebaceous follicle. They form when sebum, produced naturally by the sebaceous glands, accumulates in the pore and mixes with dead cells from the stratum corneum. This mixture creates a slightly raised plug. Unlike closed comedones, the pore remains open, allowing the lipid content to oxidise on contact with air, giving the blackhead its characteristic colouration.

Exfoliation helps prevent and reduce blackheads by acting on several fronts. By promoting the removal of dead skin cells, it limits the hyperkeratinisation responsible for pore blockage. It also contributes to keeping the follicular openings clear, facilitating the flow of sebum to the skin’s surface. Exfoliation is therefore particularly beneficial for oily, blemish-prone skin, although all skin types can benefit from it.

The stratum corneum, the outermost layer of the skin, serves a protective function and is part of the skin barrier. When it becomes excessively thick due to a build-up of dead cells, this hyperkeratinisation phenomenon can hinder the diffusion of cosmetic actives. Indeed, treatments applied to the skin’s surface then struggle to penetrate this barrier, limiting their bioavailability and, consequently, their efficacy. By promoting the removal of corneocytes at the epidermal surface, exfoliation refines the stratum corneum and restores a more even skin surface.

Skincare treatments applied after exfoliation are therefore better able to penetrate the skin and be effective.

The pigmentary spots result from an imbalance in melanogenesis, the biological process whereby melanocytes produce melanin. Under the influence of various factors, such as UV radiation, inflammation or hormonal fluctuations, melanin production can become locally excessive and unevenly distributed. This pigment accumulation appears as brown, sometimes reddish or pinkish spots that most often affect areas frequently exposed to the sun, particularly the face.

Exfoliation helps to gradually reduce these pigmentary irregularities. By removing melanin-laden cells from the epidermal surface, it accelerates cell turnover and promotes a more even complexion. Furthermore, by refining the stratum corneum, exfoliation optimises the penetration of pigmentation-targeting treatments, such as the active ingredients that inhibit melanogenesis or modulate melanin transfer.

These effects of exfoliation on skin tone uniformity are notably supported by clinical data. A study conducted in India on 40 patients with melasma compared the efficacy of 50% glycolic acid peels with 80% lactic acid peels. Patients underwent four sessions at fortnightly intervals, and the severity of pigmented lesions was evaluated using the MASI score. The results show a significantly greater reduction in MASI in the glycolic acid group compared with the lactic acid group, without any notable difference in adverse effects (erythema or post-inflammatory hyperpigmentation transient).

These data highlight the benefits of exfoliating acids, and in particular glycolic acid, in improving the appearance of brown spots.

• MILSTONE M. L. Epidermal desquamation. Journal of Dermatological Science (2004).

• RUSU A. & al. A comprehensive bibliographic review concerning the efficacy of organic acids for chemical peels treating acne vulgaris. Molecules (2023).

• RACHANA A. & al. 80% lactic acid peel versus 50% glycolic acid peel for melasma: A randomised clinical trial. Indian Journal of Dermatology (2025).