Glycolic acid, an ally against blackheads?

The blackheads, or open comedones, are common retention lesions which primarily affect combination-to-oily skin. Blackheads form when the sebum produced in excess by the sebaceous glands accumulates within the skin’s pores, combined with dead cells and impurities (pollutants, product residues, etc.). This build-up forms a plug that enlarges the pores. When exposed to air, the sebum oxidises on contact with oxygen, giving open comedones their characteristic dark colour.

The blackheads are not only unsightly: they can progress. When they rupture, they release their contents onto the surface of the skin or, if manipulated, may become infected and develop into inflammatory lesions, such as the red, painful pimples of acne. That is why it is strongly discouraged to attempt to extract your blackheads. It is better to adapt your skincare routine.

Glycolic acid is an ally of oily skin and acne-prone skin.

Derived from the alpha-hydroxy acid (AHA) family, it is characterised by its simple chemical structure and low molecular weight (76 Da), which makes it the smallest AHA and the most capable of penetrating the epidermis. The glycolic acid is primarily known for its keratolytic action: it acts by weakening the bonds that link corneocytes within the stratum corneum, facilitating their removal. By gradually releasing these cellular plugs, glycolic acid helps to unclog pores and restore sebum fluidity, thereby helping to prevent and eliminate blackheads.

The benefit of glycolic acid for reducing blackheads and tightening pores has been demonstrated in various studies. One such study evaluated the efficacy of a series of glycolic acid peels combined with home care products containing 15% glycolic acid in 40 patients with acne presenting open and closed comedones. Participants underwent four peel sessions at either 35% or 50%, depending on acne severity, spaced three weeks apart. Encouraging results were obtained in reducing comedones. By the end of the eleventh week, 32.5% of participants exhibited a marked decrease in their comedones and 57.5% showed significant improvement. It is, however, regrettable that blackheads (open comedones) were not distinguished from whiteheads (closed comedones), which somewhat limits the interpretation.

Another study explored the potential of AHAs, particularly glycolic acid, within an innovative protocol combining a chemical peel and a physical suction effect. In this study, 23 women had their faces divided into two zones: one treated solely with an AHA peel (2% glycolic acid and 2% lactic acid) and the other with the same peel combined with mechanical suction. The researchers measured pore dilation and the number of comedones before the intervention and at one, two and four weeks afterwards.

The results show that, in the group combining a peel with a physical action, blackheads and whiteheads decreased significantly from the first week, and this improvement was maintained up to four weeks. In the group that received the peel alone, a downward trend was also observed, although it was less marked. The authors conclude that combining a mild AHA peel with a physical action enhances efficacy against comedones, including blackheads, even though using a peel alone is also effective.

Note: Even though the effect of glycolic acid combined with physical aspiration appears to be more effective, it is accompanied by greater risks. Indeed, the combination of the chemical action of AHAs, which temporarily weakens the skin barrier, and mechanical stimulation can increase skin sensitivity and cause redness. This type of protocol must therefore be carried out with caution, ideally under professional supervision, and is not suitable for sensitive skin or prone to irritation.

• CHAN H.-L. & al. The effect of glycolic acid on the treatment of acne in Asian skin. Dermatologic Surgery (1997).

• KAWASHIMA M. & al. Glycolic acid chemical peeling improves inflammatory acne eruptions through its inhibitory and bactericidal effects on Propionibacterium acnes. The Journal of Dermatology (2011).

• SHIN M. K. & al. The effect of physically applied alpha hydroxyl acids on the skin pore and comedone. International Journal of Cosmetic and Dermatology (2015).

• MURUGAIAH C. & al. Efficacy and safety of superficial chemical peeling in treatment of active acne vulgaris. Anais Brasileiros de Dermatologia (2017).