Glycolic Acid

Glycolic Acid is the smallest and most well-known member of the Alpha Hydroxy Acid (AHA) family. Derived naturally from sugar cane, its low molecular weight allows it to penetrate the skin more effectively than larger AHAs like lactic or citric acid. It is widely regarded in clinical dermatology as a “workhorse” ingredient for its ability to perform controlled chemical exfoliation, making it a primary choice for addressing oily-prone skin and the early signs of photoageing.

Mechanism of Action

Glycolic Acid functions primarily as a keratolytic agent. It works by weakening the desmosomes (protein bonds) between corneocytes in the stratum corneum, the skin’s outermost layer. By reducing corneocyte cohesion, it facilitates the shedding of dead skin cells and stimulates the upward migration of new, healthy cells.

Research indicates that the efficacy of Glycolic Acid is highly dependent on its pKa (approximately 3.83) and the final pH of the formulation. Lower pH levels increase the concentration of free acid, enhancing its ability to normalise the exfoliation process. Recent clinical evaluations have explored advanced delivery systems, such as ion-pairing, to enhance stratum corneum permeation and improve skin brightness and texture while maintaining a superior safety profile Shake-Induced Temporary Ion-Pairing Between Lecithin and Glycolic Acid for Enhanced Exfoliation in a Novel Biphasic Serum: Comparative Ex Vivo and in Vivo Randomised Studies. Furthermore, its ability to soften keratin plugs makes it an effective intervention for follicular hyperkeratosis The Effectiveness of Topical Keratolytics (Alpha Hydroxy Acids/Beta Hydroxy Acids/Urea) in Treating Keratosis Pilaris: A Review of the Literature.

Dermatological Benefits

• Surface Retexturising: By accelerating desquamation, it smooths rough patches and reduces the appearance of fine lines and wrinkles.
• Pore Refinement: It helps clear problematic debris and excess surface oil from the follicular opening, which visually minimises the appearance of enlarged pores.
• Clarifying Action: Regular use helps manage congestion and reduces the frequency of surface imperfections, particularly in oily or blemish-prone skin types.
• Tone Evening: It assists in dispersing accumulated pigment in the upper layers of the epidermis, leading to a more radiant and uniform skin tone.
• Dermocosmetic Support: It is frequently integrated into regimens for oily skin to support overall skin health and clarity Integrating Dermocosmetics Into Acne Care in Latin America.

Formulation Nuances

The performance of Glycolic Acid is dictated by its concentration and the vehicle in which it is delivered. High-strength formulas (typically around 8-10% for daily consumer use) are often delivered in hydroalcoholic solutions to maximise penetration in oily skin types. Because Glycolic Acid is highly bioactive, formulations often include buffering agents like Ammonium Hydroxide to balance efficacy with skin tolerability. It is essential that the formulation maintains an acidic pH to ensure the acid remains in its “active” un-dissociated form.

Contraindications

• Photosensitivity: Glycolic Acid increases the skin’s sensitivity to ultraviolet (UV) radiation. Daily application of a broad-spectrum sunscreen is mandatory during use and for one week following cessation.
• Sensitive Skin: Due to its rapid penetration, it may cause stinging or redness in those with reactive skin or a compromised skin barrier.
• Ingredient Interactions: Caution should be exercised when layering Glycolic Acid with other potent actives, such as prescription retinoids or high-strength L-ascorbic acid, to avoid over-exfoliation and irritation.