Importance of hydroxy acids in your skin care routine Series α-hydroxy acids: Glycolic Acid

What are HA’s?

Hydroxy acids (HA’s) have been around for decades to clinically treat a range of skin conditions. The most common forms of hydroxy acids are α-hydroxy acids, β-hydroxy acids, polyhydroxy acids, and bionic acids (PHA with an additional sugar molecule attached to the PHA structure). They are found in over the counter skin care products and also in spas as a peel (you could do a peel at home but I just wouldn’t take the risk because the concentration is really high and you may damage your skin). The most popular ones you probably have come across are glycolic acid, lactic acid and salicylic acid.


Due to HA’s small molecular size they are able to penetrate the skin. Studies show that HAs improve photo aged skin by decreasing roughness, discolouration, solar keratoses and improving overall pigmentation of the skin. Moreover, HAs have shown to increase the density of collagen while improving the quality of the elastic fibres in our skin cells. Going as far as protecting your skin from UVB which I’ll get into later.

α-hydroxy acids (AHA)

1. Glycolic Acid

Let’s begin with α-hydroxy acid (AHA). The two most common AHA’s that you will or have already encounter are lactic acid and glycolic acid. Glycolic acid is derived from fruits that that are high in sugar such as sugar cane or sugar beets but can also be made synthetically. In addition to what was mentioned above, glycolic acid also aides in skin hydration and in the exfoliation of the skin. As we age, the rate at which are old skin cells are replaced with new ones decreases, this is why exfoliation is very important as we mature.  Researchers discovered that glycolic acid was responsible for the thinning of the stratum corneum (the outermost layer of the epidermis, consisting of dead cells) and for the thickening of the epidermis. It is thought the exfoliation properties is due to the thinning of the stratum corneum meanwhile combating the thinning of our skin as we age.


One study showed that the use of glycolic acid resulted in an increase of the hyaluronic acid gene expression both in the epidermal and dermal cells alongside an increase in the expression of the collagen gene. How great is that! Both are very important for both the prevention of wrinkles and reducing the appearance of wrinkles.

In diseased and aged skin there is a loss of acidity in the startum corneum and with the use of glycolic acid containing water in oil emulsion helped reduced pH level. It is suggested that the loss of acidity in the skin may interfere with biological functions in the skin. Another interesting study found that 10% glycolic acid containing oil-in-water emulsion improved acne. So clearly glycolic acid is definitely a must have in any skin care routine.

It’s important to also mention that some studies have shown that the continuous use of glyocolic acid can make your skin more sensitive to sun, potentially causing skin damage from UVB. My suggestion would be to use a good sunscreen every day. Just make it a part of your morning routine.


When starting to use glycolic acid, I recommend starting off with a low concentration and using it every other day then building from there. Perhaps do a spot treatment first to see how your skin reacts. I personally did find glycolic acid itself to be hydrating so I would skip my moisturizer on the days I would use my glycolic acid serum. I found Peter Roth’s 10% glycolic acid was great but as well as Neostrata 10% glycolic acid (much more affordable and I found it worked just as well as Peter Roth’s). Now I use Neostrata cleanser with glycolic acid. Do you use glycolic acid and if so what products are your favourite(s).

My next topic will be on lactic acid. Thanks for reading! And please share and subscribe!


Stiller, Matthew J., et al. “Topical 8% Glycolic Acid and 8% L-Lactic Acid Creams for the Treatment of Photodamaged Skin: A Double-Blind Vehicle-Controlled Clinical Trial.” Archives of Dermatology, vol. 132, no. 6, 1996., pp. 631-636doi:10.1001/archderm.1996.03890300047009.

Ditre, C. M., et al. “Effects of Alpha-Hydroxy Acids on Photoaged Skin: A Pilot Clinical, Histologic, and Ultrastructural Study.” Journal of the American Academy of Dermatology, vol. 34, no. 2 Pt 1, 1996., pp. 187.

Kristensen, B., and O. Kristensen. “Topical Salicylic Acid Interferes with UVB Therapy for Psoriasis.” Acta dermato-venereologica, vol. 71, no. 1, 1991., pp. 37.

PHAs and Bionic Acids: Next Generation Hydroxy Acids

Mammone, Thomas, et al. “Salicylic Acid Protects the Skin from UV Damage.” Journal of cosmetic science, vol. 57, no. 2, 2006., pp. 203.

Park, K. S., et al. “Effect of Glycolic Acid on UVB-Induced Skin Damage and Inflammation in Guinea Pigs.” Skin pharmacology and applied skin physiology, vol. 15, no. 4, 2002., pp. 23

Okuda, M., et al. “Negligible Penetration of Incidental Amounts of Alpha-Hydroxy Acid from Rinse-Off Personal Care Products in Human Skin using an in Vitro Static Diffusion Cell Model.” Toxicology in vitro : an international journal published in association with BIBRA, vol. 25, no. 8, 2011., pp. 2041-2047doi:10.1016/j.tiv.2011.08.005.

DiNARDO, JOSEPH C., GARY L. GROVE, and LAWRENCE S. MOY. “Clinical and Histological Effects of Glycolic Acid at Different Concentrations and pH Levels.”Dermatologic Surgery, vol. 22, no. 5, 1996., pp. 421-424doi:10.1111/j.1524-4725.1996.tb00341.x.

Bernstein, Eric F., et al. “Glycolic Acid Treatment Increases Type I Collagen mRNA and Hyaluronic Acid Content of Human Skin.” Dermatologic Surgery, vol. 27, no. 5, 2001., pp. 429-433doi:10.1046/j.1524-4725.2001.00234.x.

Abels, Christoph, et al. “A 10% Glycolic Acid Containing Oil-in-Water Emulsion Improves Mild Acne: A Randomized Double-Blind Placebo-Controlled Trial: Glycolic Acid Improves Mild Acne.” Journal of Cosmetic Dermatology, vol. 10, no. 3, 2011., pp. 202-209doi:10.1111/j.1473-2165.2011.00572.x.


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