Glycolic Acid 

• INCI Name: Glycolic Acid
• Chemical Name (IUPAC): 2-hydroxyacetic acid
• Molecular Formula: C₂H₄O₃
• CAS No.: 79-14-1 / 26124-68-5
• EINECS No.: 201-180-5 / 815-723-4
• COSING REF No: 34147
• Common Names: Glycolic Acid, Hydroxyacetic Acid, AHA (Alpha Hydroxy Acid)
• Appearance: Varies between being colourless to slightly yellow liquid or white crystalline solid (depends on concentration and form)
• Source: Naturally derived from sugarcane, sugar beets, pineapple, cantaloupe and unripe grapes
• Chemical Classification: Alpha Hydroxy Acid (AHA)
• Molecular Weight: 76.05 g/mol
• pH Range (Cosmetic Use): Typically formulated between pH 3.0–4.0 for exfoliation products

Glycolic acid has been identified by Sharad (2013) as a popular skincare ingredient that is mostly used for its exfoliating and skin renewing capabilities. Being one of the Alpha Hydroxy Acids (AHAs), it is derived from sugarcane, fruits etc. the reduced molecular size of Glycolic acid allows it to penetrate the layers of skin while promoting bright, smooth and younger-looking complexion (Lukic et al., 2021). The ingredient helps in reducing dullness and pigmentation while reducing acne scars and uneven texture, making modern day beauty and wellness brands to adopt it. 

Functional Groups Present in Glycolic Acid

Hydroxyl Group (-OH):

• Offers Glycolic Acid due to its strong abilities to exfoliate and act as a humectant, thus assisting to remove dead skin cells while attracting and retaining moisture within the skin layers (Jem and Tan, 2020).

• Facilitates moisturizing and absorption of skincare products into the skin, which improves moisture retention as well as skin texture.

Carboxylic Acid Group (-COOH): 

• Contributes to the natural acidity of glycolic acid while enabling it to react well with the skin and perform different skin regeneration roles (Salusjärvi et al., 2019).

• Dissolves the accumulation of dead skin cells and supports the process of peeling to ensure that rough skin is removed, leaving behind smooth and bright skin.

Chemical Structure of Glycolic Acid:

Glycolic Acid contains HOCH₂COOH, which can be divided under:

• One hydroxyl (-OH) group

• One carboxyl (-COOH) group

• A simple two-carbon backbone

To conclude, Glycolic Acid has a hydroxyl functional group (-OH) and a carboxylic acid group (-COOH). These functional groups make skin conditioning and exfoliation possible (Kornhauser, Coelho and Hearing, 2010). The small size of the Glycolic Acid molecule makes it more effective when penetrating the skin, while promoting smoother and brighter-looking skin.

1. Exfoliates Dead Skin Cells

Glycolic acid is an excellent exfoliator that gently removes the dead skin cells from the stratum corneum or the topmost skin layer (Bergfeld et al., 1997). It works by loosening the bond between the dead skin cells and the skin surface while promoting healthy cell renewal process to reveal clear and bright skin complexion. 

Benefits include:

• Brighter-looking skin

• Improved skin smoothness

• Reduction in rough texture

• Better absorption of skincare products

2. Helps Reduce Hyperpigmentation

Glycolic Acid is an effective ingredient that is used by most beauty and wellness companies as it is effective in treating skin discoloration, tans, acne scars and dark patches (Garg, Sinha and Sarkar, 2009). It helps in disrupting melanin synthesis, which is the primary cause of skin pigmentation, thereby slowing pigmentation. Furthermore, being an AHA, glycolic acid penetrates deep down the skin layers while removing dead skin cells while facilitating quicker cellular turnover, to reveal clear looking skin over time. 

3. Improves Skin Texture

Glycolic acid helps in improving skin texture by enabling deep chemical exfoliation that helps in removing the dead skin cells while dissolving the bonds between upper skin and the dead skin cells while boosting the natural cell renewal process (Sharad, 2013). It boosts collagen production that helps in promoting skin’s elasticity, resulting in well-toned texture. Therefore, Glycolic acid takes care of uneven skin surface, enlarged pore appearance and acne related skin concerns.

4. Supports Anti-Ageing

Glycolic acid helps in stimulating fibroblasts which are responsible for promoting collagen production. Being an AHA the ingredient penetrates the skin layers and improves skin elasticity by providing the structural support which plumps and smoothens skin texture while fighting fine lines and wrinkles. Furthermore, Glycolic acid triggers glycosaminoglycans (GAGs) synthesis which helps in binding moisture to the skin surface while keeping the skin hydrated, thereby avoiding roughness, creases and fine lines (Narda et al., 2021). Therefore, regular use of the ingredient helps in supporting firming the skin by boosting skin renewal. 

5. Helps with Acne-Prone Skin

Glycolic acid helps in unclogging skin pores by dissolving the bonds between dead skin cells while the chemical exfoliant helps in removing dead skin cells, debris and excess oil from the skin surface (Sharad, 2013). It helps in fading acne scars and reduces hyperpigmentation by boosting rapid cell turnover, revealing clear and brighter skin. 

Benefitting from the use of Glycolic acid needs careful consideration and introduced carefully into skincare routines, as a beginner. Experts suggest that beginners must start with products with lower concentration of glycolic acid composition, typically 5-7 ml to avoid irritation. Furthermore, as Glycolic acid can increase skin’s sensitivity to direct sunlight or UV exposure, using a broad-spectrum sunscreen is mostly suggested by skincare experts to avoid UV damage and further pigmentation. 

Finally, avoiding over exfoliation using scrubs rich in high concentration of glycolic acid is suggested as it helps in reducing inflammation, redness, irritation etc. Performing a patch test before completely applying glycolic-infused products on the skin is advised to reduce the chances of unwanted sensitivity and avoid skin irritation.  

Although Glycolic acid is generally considered safe in cosmetic skincare and there aren’t any complain of any allergy or inflammatory outbreak among users or research papers. However, many people with sensitive skin might initially experience mild redness, tingling sensation, temporary dryness and increased skin sensitivity. These effects are mostly temporary and might reduce consistently as the skin starts adapting.

• Bergfeld, W., Tung, R., Vidimos, A., Vellanki, L., Rernzi, B. and Stanton-Hicks, U., 1997. Improving the cosmetic appearance of photoaged skin with glycolic acid. Journal of the American Academy of Dermatology, 36(6), pp.1011-1013. https://www.sciencedirect.com/sdfe/pdf/download/eid/1-s2.0-S0190962297802903/first-page-pdf
• Fartasch, M., Teal, J. and Menon, G.K., 1997. Mode of action of glycolic acid on human stratum corneum: ultrastructural and functional evaluation of the epidermal barrier. Archives of dermatological research, 289(7), pp.404-409. https://www.researchgate.net/profile/Manige-Fartasch/publication/13970736_Mode_of_action_of_glycolic_acid_on_human_stratum_corneum_Ultrastructural_and_functional_evaluation_of_the_epidermal_barrier/links/566952bb08ae193b5fa27dd8/Mode-of-action-of-glycolic-acid-on-human-stratum-corneum-Ultrastructural-and-functional-evaluation-of-the-epidermal-barrier.pdf
• Garg, V.K., Sinha, S. and Sarkar, R., 2009. Glycolic acid peels versus salicylic–mandelic acid peels in active acne vulgaris and post-acne scarring and hyperpigmentation: a comparative study. Dermatologic Surgery, 35(1), pp.59-65. https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/j.1524-4725.2008.34383.x
• Jem, K.J. and Tan, B., 2020. The development and challenges of poly (lactic acid) and poly (glycolic acid). Advanced industrial and engineering polymer research, 3(2), pp.60-70. https://www.sciencedirect.com/science/article/pii/S2542504820300026
• Kornhauser, A., Coelho, S.G. and Hearing, V.J., 2010. Applications of hydroxy acids: classification, mechanisms, and photoactivity. Clinical, cosmetic and investigational dermatology, pp.135-142. https://www.tandfonline.com/doi/pdf/10.2147/CCID.S9042
• Lukic, M., Filipovic, M., Pajic, N., Lunter, D., Bozic, D. and Savic, S., 2021. Formulation of topical acidic products and acidification of the skin–Contribution of glycolic acid. International Journal of Cosmetic Science, 43(4), pp.419-431. https://www.researchgate.net/profile/Milica-Lukic-2/publication/350947662_Formulation_of_topical_acidic_products_and_acidification_of_the_skin_-_Contribution_of_glycolic_acid/links/6762c25e8cfcdf077fe3a556/Formulation-of-topical-acidic-products-and-acidification-of-the-skin-Contribution-of-glycolic-acid.pdf
• Narda, M., Trullas, C., Brown, A., Piquero‐Casals, J., Granger, C. and Fabbrocini, G., 2021. Glycolic acid adjusted to pH 4 stimulates collagen production and epidermal renewal without affecting levels of proinflammatory TNF‐alpha in human skin explants. Journal of cosmetic dermatology, 20(2), pp.513-521. https://pmc.ncbi.nlm.nih.gov/articles/PMC7891644/
• Salusjärvi, L., Havukainen, S., Koivistoinen, O. and Toivari, M., 2019. Biotechnological production of glycolic acid and ethylene glycol: current state and perspectives. Applied microbiology and biotechnology, 103(6), pp.2525-2535. https://link.springer.com/content/pdf/10.1007/s00253-019-09640-2.pdf
• Sharad, J., 2013. Glycolic acid peel therapy–a current review. Clinical, cosmetic and investigational dermatology, pp.281-288. https://www.tandfonline.com/doi/pdf/10.2147/CCID.S34029