Glycolic acid (hydroxyacetic acid) — the most commonly used form of alpha hydroxy acids (AHAs) and one of the most effective ingredients in today’s skin-rejuvenation business. It works on both the epidermis and dermis. Scientists and formulators believe glycolic acid has greater penetration potential largely due to its smaller molecular weight. Glycolic Acid dissolves the “glue” that holds dead skin cells together in the epidermis, reduces corneocyte cohesion, allowing these dead skin cells to be easily dissolved or exfoliated to reveal new skin underneath and eventually building the thickness of the epidermis. In the dermis, it increases ground substance (boosts collagen remodeling, increases elastin, and hyaluronic acid) and improves skin hydration. The skin’s ability to bind and retain an impressive amount of moisture is enhanced. Research on glycolic acid conducted at UCLA and the Hahnemann University School of Medicine in Philadelphia, saw a 25% increase in skin thickness, improved quality of elastic fibers and increased density of collagen and concluded that glycolic acid "produced a significant reversal of epidermal and dermal markers of photo aging" after 6 months of usage.
Glycolic acid proves beneficial for acne-prone skin as it helps keep pores clear of excess keratinocytes. It is also used for lightening hyperpigmentation, diminishing the signs of age spots, as well as actinic keratosis. However, glycolic acid is most popularly employed in anti-aging cosmetics because of its hydrating, moisturizing, and skin-normalizing abilities, leading to a reduction in the appearance of fine lines and wrinkles. Regardless of the skin type, glycolic acid use is associated with softer, smoother, healthier, and younger looking skin. The pH should be 3.0 – 4.0 and the percentage should be 10-20%. Only use a “pea-size.” Overuse can cause irritation. Products with concentrations below 8% appear to be of no benefit. Glycolic acid is naturally found in sugarcane but synthetic versions are most often used in cosmetic formulations.