It's important to note that dermatologists we've interviewed agree that glycolic acid is most ideal for oily and acne-prone skin types. However, if you have sensitive skin, you can still proceed — with caution. Consult your board-certified dermatologist before using the ingredient to figure out which treatments (coupled with soothing ingredients like glycerin) are best for you. In another study by Atzori et al, 70% GA was used in comedonic acne, papulopustular, and nodular/cystic acne. While comedones improved rapidly, papulopustular acne improved after six peel sessions, and nodulocystic lesions required ten sessions at three-week intervals. A significant improvement of coexisting post-acne superficial scarring was noted. Patient tolerance and compliance were both found to be excellent. 22 Saadawi AN, Esawy AM, Kandeel AH, El-Sayed W. Microneedling by dermapen and glycolic acid peel for the treatment of acne scars: Comparative study. J Cosmet Dermatol. 2019;18(1):107-114. View abstract.

Lactic acid, which is structurally identical to glycolic acid with the exception of an additional methyl group at the β-carbon end, has a lower pKa and thus a lower pH than glycolic acid at equivalent concentrations, allowing for efficient chemoexfolation at lower concentrations. 35 – 37 , 40 Clinically, lactic acid has demonstrated comparable efficacy in the treatment of photodamage, superficial hyperpigmentation, and fine rhytides compared to standard glycolic acid peels.Because lactic acid has a lower pH than glycolic acid, a lower concentration is often used to achieve an equivalent depth of keratocoagulation compared to glycolic acid, which allows a favorable side effect profile and recovery time. As with glycolic acid, neutralization is necessary, and exfoliation after treatment typically occurs over several days with complete reepithelialization in 7 to 10 days. 1 , 2 , 17 , 27 , 28 , 39 In a comparative study of 10%–20% TCA versus 20%–35% GA peels for the treatment of melasma, similar improvement was seen with both peels. However, the GA peel was seen to be associated with fewer side effects than the TCA peel, and gave the added benefit of facial rejuvenation. 39 After neutralization, the skin may be rinsed or cleansed gently. Following application, an initial erythema might become red and is often accompanied by edema. Stringy or patchy light frosting (Level I) might subsequently develop, indicating epidermolysis with separation of the epidermis from the underlying dermis. Development of frank or uniform frosting (≥Level II) indicates deeper destruction into the dermis and is not desirable, as this is meant to be a relatively superficial peel. Exfoliation typically occurs over several days, and reepithelialization is complete within 7 to 10 days. 1 , 2 , 7 , 8 , 9 , 21 The minor side effects reported are: erythema, stinging sensation, sensation of pulling of facial skin, mild burning, and transient postinflammatory hyperpigmentation. Unbuffered GA can cause erosive blisters and scarring. 40 , 58 In rare cases, hypopigmentation, persistent erythema, and flare-up of pimples have been reported. 24 , 36 , 59As a leave-on treatment, I don't recommend using glycolic acid every day because it can cause excessive irritation," says Wnek. "Incorporate it slowly into your routine and work your way up to every other day or every two days, if tolerated."

Self-precipitation of the peeling agent accounts for little penetration and a good safety profile, thus reducing the risk of postpeel hyperpigmentation, especially in the darker skin types.[ 16] These features have made salicylic acid peel superior to glycolic acid peel in comparative studies conducted earlier in dark-skinned individuals. Studies have also shown beneficial effect of salicylic acid peel in postinflammatory pigmentation in dark-skinned individuals.[ 16, 17] Similar effect on postinflammatory hyperpigmentation was noted in this study. Salicylic acid decreases postacne hyperpigmentation by its anti-inflammatory effects. Ahn and Kim[ 18] found salicylic acid to have a whitening effect on the skin as well. Mandelic acid also has a beneficial effect in improving skin pigmentation.Abels C, Kaszuba A, Michalak I, Werdier D, Knie U, Kaszuba A. A 10% glycolic acid containing oil-in-water emulsion improves mild acne: a randomized double-blind placebo-controlled trial. J Cosmet Dermatol. 2011 Sep;10(3):202-9. View abstract. Kaminaka C, Uede M, Matsunaka H, Furukawa F, Yamomoto Y. Clinical evaluation of glycolic acid chemical peeling in patients with acne vulgaris: a randomized, double-blind, placebo-controlled, split-face comparative study. Dermatol Surg. 2014 Mar;40(3):314-22. View abstract. If you’re less concerned about acne or wrinkles but find yourself with pesky dry patches or unevenness that you’d like to treat, consider glycolic acid an easy ally to the cause. Glycolic acid’s efficacy is based on the concentration and frequency of use, but another important consideration is combination therapy, as adding another topical or professional treatment can yield greater results. Glycolic Acid Products You may have heard the words glycolic acid. The name might ring a bell because it’s one of the most highly trending buzzwords on the skincare scene. It can be found in everything from moisturisers to serums to chemical peels. It can be used day time or night time. It prevails against a variety of different skincare issues. But where did it come from? Why does it work? Can it really be that great? We’ve created a complete breakdown to help you navigate what glycolic acid is really all about. Our complete guide to the benefits of glycolic acid will:

Dayal S, Kaur R, Sahu P. Efficacy of microneedling with 35% glycolic acid peels versus microneedling with 15% trichloroacetic acid peels in treatment of atrophic acne scars: A randomized controlled trial. Dermatol Surg 2022;48(11):1203-1209. View abstract. Kubiak M, Mucha P, Rotsztejn H. Comparative study of 15% trichloroacetic acid peel combined with 70% glycolic acid and 35% trichloroacetic acid peel for the treatment of photodamaged facial skin in aging women. J Cosmet Dermatol 2020;19(1):137-146. View abstract. Kim et al did a comparative study using 70% GA and Jessner’s Solution (resorcinol 14%, lactic acid 14%, and salicylic acid 14%, in an alcohol base), respectively, in two groups of patients with acne. Three peel sessions were done for each group. Though acne improved in both to the same extent, there was more exfoliation seen in the Jessner’s Solution group. Hence, GA was found to be the better tolerated of the two peels for the treatment of acne in Asian patients. 23 Serial GA peels (from 35%–50%, and 70% every second peel) plus combination topical therapy (azelaic acid and adapalene) in 28 women with melasma found better results in the group receiving chemical peel plus topical therapy ( P = 0.048), but only when the GA concentration was 50% or higher. 35 A study by Erbağci and Akçali concluded that a 70% GA peel performed every 2 weeks resulted in significant improvement in atrophic acne scarring, as compared to 15% GA cream used daily. In one group of 23 patients, GA peels were performed bi-weekly with increasing application time and acid concentration from 20%–70%. A second group of 20 patients was instructed to use 15% GA cream twice daily for a period of 24 weeks. It was seen that six patients, using 70% GA, showed significantly better results than daily use of 15% GA for 24 weeks ( P< 0.05). Furthermore, apparently good responses were observed in the peel group only ( P< 0.01). 26Application of Jessner’s solution or solid CO2 with acetone, an older technique, prior to the application of glycolic acid or TCA results in a more homogenous disruption of the epidermal barrier and a more thorough removal of natural oils from the skin, providing greater penetration of the acid and a more uniform frosting. 2 , 3 , 5 , 7 – 9 , 15 , 19 – 23 Furthermore, the resultant frosting is often better controlled, with less risk of “hot spots” that can occur with higher concentrations of TCA or glycolic acid. 2 , 3 , 5 , 7 – 9 , 15 , 19 – 23 We’ve already mentioned all the ways that glycolic acid works to slough off dead skin cells, but did we mention that it also helps to attract moisture from the air, coaxing it into the skin to increase hydration and minimise any additional dryness? Amazing, right? Not only that, but it’s a great product to use in the morning in the form a cleanser or serum because it helps to prep your skin for other product use. It sets your skin up for smearing on your favourite moisturiser and even smoothes your skin, ready for your makeup application. While providing powerful exfoliation, the powerhouse AHA also improves skin tone, texture, and minimizes hyperpigmentation. You can also expect some boosts to skin's collagen production —and since the acid helps remove dead skin cells and prevents other buildup from clogging your pores, products with the ingredient can help stop acne breakouts. In short, there's very little that glycolic acid can't do. Helps fight acne."By exfoliating the top layer of dead skin on the skin’s surface, you minimize the risk that the old, dead skin gets mixed with sebum, which creates acne," says Dr. Hartman.