Retinol and glycolic acid are chemicals commonly used in skin treatments. Retinol, a form of vitamin A, has a number of physiological effects on your skin, both when ingested or applied topically. Glycolic acid belongs to a family of alpha-hydroxy acids that have an effect on your skin when applied topically. Both of these chemicals have a number of positive skin effects, as well as certain negative side effects.
One effect of glycolic acid on your skin is chemical exfoliation. The outer layers of your skin are made up of dead skin cells, called keratinocytes. These cells, packed with protein, slough off slowly over time, allowing younger cells to reach your skin's surface. Glycolic acid breaks up these outer layers of cells, revealing the newer cells underneath. Johns Hopkins University explains that glycolic acid peels, when applied repeatedly over time, usually twice per year, provide a deep exfoliation for the skin. Regular glycolic acid peels can promote a youthful appearance of your skin, preventing the dryness and dullness that can occur due to a buildup of dead cells on the surface of your skin.
Generation of New Skin Cells
An effect of retinol on your skin is the proliferation of skin cells. Since retinol is such a small molecule, topical application of a retinol cream allows the chemical to penetrate into deeper layers of your skin. These deeper layers contain live skin cells, which continually proliferate, giving rise to new cells that eventually move towards the surface of your skin. The Linus Pauling Institute at Oregon State University indicates that retinol treatments and renewal of skin cells also helps maintain the integrity of your skin, and helps treat diseases including acne and psoriasis. Overall, regular treatment with retinol under the supervision of a physician can improve the health and appearance of your skin.
One negative effect of both glycolic acid and retinol on your skin is increased photosensitivity. Ultraviolet rays from the sun penetrate your outer layers of skin. This radiation can alter the molecular structure of your DNA, as well as generate harmful chemicals called reactive oxygen species, that may further damage your cells, explains the University of Missouri. Your skin slowly builds protection against UV rays through the production of the protein melanin. However, the new cells revealed following a retinol or glycolic acid treatment may not have developed this protection against UV rays. In the weeks following these treatments, always wear sunscreen or protective clothing, and avoid prolonged exposure to the sun's rays.