Glycolic acid is an alpha hydroxy acid (AHA) widely used in cosmetics and dermatology. So what does glycolic acid do at home strengths? Trials of 8% and 10% formulas found modest gains in signs of sun damage and significant improvement in mild acne. It also makes skin more sensitive to UV light, so sunscreen belongs in the routine. [1, 2, 3, 4]
In this article
- What is glycolic acid?
- What does glycolic acid do for skin?
- How do you use glycolic acid on your face?
- What should you expect?
- Why does glycolic acid call for sunscreen?
- What can you combine it with?
- Who should be careful?
- What should you check when choosing and storing it?
- Frequently asked questions
- References
What is glycolic acid?
Glycolic acid belongs to the alpha hydroxy acids (AHAs), and reviewers single it out as an especially common one. A dermatology review describes clinically tested uses ranging from skin hydration to acne. Depending on its concentration, the same molecule can sit in a cosmetic or in a medical product. [1]
Alpha hydroxy acids, beta hydroxy acids, polyhydroxy acids and bionic acids are separate classes. BHA in skincare usually means salicylic acid, which has its own guide. The base formula, or vehicle, also shapes the result, so two products with the same acid are not automatically equivalent. [6]
In a small study with six volunteers, 12% glycolic acid shortened the turnover time of the stratum corneum, the outermost layer of skin, more than the retinoic acid it was compared with (12.8 versus 15.8 days). It also caused fast redness and more water loss; the authors suggested faster turnover may be partly linked to irritation. [7]
This guide covers toners, serums, creams and cleansers used at home. A clinic peel is a different procedure, planned after a skin assessment and stopped by neutralizing the acid on time; peel results appear below only as context. [8]
What does glycolic acid do for skin?
Most of the evidence concerns signs of sun damage, acne and dark spots. At home strengths, controlled trials are few and mostly small, and several stronger-looking results come from clinic peels. For each benefit, check which concentration was tested and how it was applied before expecting the same from your own bottle.
Sun damage and fine lines
In a double-blind trial, 74 women aged 40 to 70 with sun-damaged facial skin applied an 8% glycolic acid cream, an 8% lactic acid cream or a cream without an active ingredient twice daily for 22 weeks. On the face, 76% of the glycolic acid group improved by at least one grade in overall photodamage severity, compared with 40% of the vehicle group. The authors called the benefit modest. [2]
So the evidence points to a modest gain in some signs of sun damage, not to vanishing lines, and it comes from a single-center study of women only. In a pilot study, a 25% AHA lotion applied to one forearm for about six months left skin roughly 25% thicker, with denser collagen in biopsies. The abstract gives no participant count, and the lotions contained glycolic, lactic or citric acid, so the result cannot be credited to glycolic acid alone. [9]
Acne-prone skin
In a double-blind trial with 120 people who had mild acne, a 10% glycolic acid emulsion at pH 4 was used on its own every evening for 90 days. Acne improved significantly in the active group through day 90, and the difference from placebo was already significant by day 45. Reported side effects did not differ between the groups. [3]
The result is encouraging but belongs to one formula and to mild acne; the abstract gives no number for the size of the improvement. Painful, widespread or scarring breakouts need more than a skincare product, and the acne guide explains when to see a dermatologist.
Dark spots and melasma
A 2024 systematic review of chemical peels for melasma (24 studies, 1,075 participants) found glycolic acid the safest and most effective peeling agent. These were in-clinic procedures, though, and the data were too varied for a meta-analysis. [10]
Evidence for home products is thinner. In a study with ten Asian women, a cream with 10% glycolic acid and 2% hydroquinone improved melasma on both sides of the face; because of the hydroquinone, the effect cannot be assigned to glycolic acid alone. The side that also received peels looked better, but not significantly. [11] The dark spots guide helps you tell spot types apart; melasma needs a clinician’s diagnosis and plan.
Acne scars
In 58 women with pitted acne scars, researchers compared peels of 20% to 70% every two weeks, a 15% glycolic acid cream used at home once or twice daily, and a placebo cream. The home cream was better tolerated, but a clearly good response appeared only in the peel group. [12] Red or brown marks and pitted scars are different problems; the acne scars guide explains the difference.
How do you use glycolic acid on your face?
Add glycolic acid as the only new step, follow the label, and do not skip daytime sunscreen. Study schedules were specific to their products: one cream was applied twice daily, one emulsion only in the evening. Neither schedule replaces the instructions on your own product. [2, 3]
A practical way to start:
- Begin with a few evenings a week and watch how your skin responds.
- Apply to clean, dry skin. Rinse off wash-off products as directed; do not guess contact times.
- Keep other exfoliants off that evening. Introduce glycolic acid on its own first.
- Keep your moisturizer the same, so you can tell what caused any irritation.
- Wear sunscreen every morning. The sun section below explains why.
Toner, serum or cleanser?
The controlled trials in this guide tested creams and an emulsion, not toners, so we cannot report a separate result for each format. In practice, a toner goes on after cleansing in a thin layer, away from the eyes and lips, followed by moisturizer.
Using a glycolic acid toner and serum on the same evening goes beyond the single-product use tested in the studies. If you notice stinging, redness or peeling, use it less often or pause; applying it more often to “train” your skin is not supported by research.
What percentage and pH?
Home-use trials tested an 8% cream and a 10% emulsion with a pH of 4. [2, 3] The Cosmetic Ingredient Review (CIR) Expert Panel recommends 10% as the maximum safe AHA concentration in products. Yet when researchers checked 50 exfoliating products sold online, 19 exceeded that level and 12 did not state a concentration at all. [5]
International guidelines recommend specific concentration and pH levels to limit irritation, but the concentration with the best balance of effect and side effects has not been precisely defined. [13] In the studies above, 20% to 70% was used for clinic peels; a higher number on a home product does not mean a better result. [11, 12]
Morning or night, and how often?
The acne trial used its product every evening, the sun damage trial twice daily. [2, 3] Because glycolic acid makes skin more sensitive to UV light, many people apply it at night; if you use it in the morning, sunscreen is essential. Whether daily use suits you depends on the product and your skin. Aim for steady, comfortable use rather than maximum frequency.
What should you expect?
Mild stinging or flushing can occur during the first applications; what matters is whether it fades or persists. In a small study, 12% glycolic acid quickly caused marked redness, raised water loss through the skin and lowered skin hydration. A network meta-analysis comparing treatments for sun-damaged skin also found a higher risk of side effects with glycolic acid. [7, 14]
Home-strength trials reported good tolerance: one of 74 participants left the 8% cream trial because of irritation, and side effects with the 10% emulsion matched placebo. [2, 3]
| Period | What you may notice | How to read it |
|---|---|---|
| First applications | Brief stinging, mild redness | Lasting burning or swelling is not normal |
| First weeks | Mild dryness | If dryness grows, use it less often |
| Around day 45 | First significant difference from placebo in the acne trial | One study’s timeline, not a promise |
| Week 22 | Assessment point of the sun damage trial | Expect a modest change |
Our sources contain no evidence that breakouts must get worse before they improve. Do not assume new breakouts are a passing “purge”: note when they started, stop the product if they continue, and see a dermatologist if needed.
Why does glycolic acid call for sunscreen?
Glycolic acid makes skin more sensitive to sunlight. In a randomized, double-blind study, 10% glycolic acid at pH 3.5 was applied to the backs of 29 volunteers for four weeks. After UV exposure, treated skin showed more sunburn cells and burned at a lower UV dose. The difference had disappeared one week after the applications stopped. [4]
The US Food and Drug Administration (FDA) therefore recommends a sunburn alert on cosmetics with AHAs, yet only 16 of 50 product pages in an online survey showed it. [5] The UV study was small and limited to white participants and back skin, and research on long-term hydroxy acid use and sun-related skin cancer is very limited. [6]
In practice, apply broad-spectrum sunscreen every morning while you use glycolic acid and for the week after you stop, and reapply during the day. The sunscreen guide covers amount and reapplication.
What can you combine it with?
None of our sources tested the best order for layering glycolic acid with other actives. The practical rule is to avoid stacking exfoliating or irritating products on the same evening and to introduce new products one at a time. The table summarizes that approach; it is not a proven compatibility chart.
| Ingredient | Practical approach |
|---|---|
| Retinol | Use on different evenings; do not start both at once |
| Salicylic acid (BHA) | Do not layer on the same evening; if one acid is enough, skip the second |
| Azelaic acid | Separate them if irritation appears |
| Vitamin C | If your skin reacts, use vitamin C in the morning and glycolic acid at night |
| Moisturizer, hyaluronic acid | Can support hydration; not shown to prevent irritation |
| Sunscreen | Every morning |
The network meta-analysis that assessed retinol and glycolic acid found a higher side-effect risk for glycolic acid. [14] That is a reasonable argument for keeping them on separate evenings, not proof that combining them is harmful.
Who should be careful?
Sensitive, easily flushed skin and a weakened barrier are more likely to react, since glycolic acid can quickly raise redness and water loss. If you already have dryness, stinging or flaking, first repair your skin barrier. With diagnosed rosacea or eczema, ask your clinician first. [7]
Skin type matters too. A peel review reports glycolic acid peels as very safe in Fitzpatrick skin types I to IV; that statement does not cover darker skin types. If you have deeper skin that marks easily, start any new acid cautiously. [8]
Do not recreate a clinical peel at home. A safe glycolic acid peel requires a medical history, a skin examination, preparation and timely neutralization; high-percentage home “peels” or pure acid solutions skip those steps. [8] For pregnancy, see the questions below.
What should you check when choosing and storing it?
Look for the glycolic acid percentage and clear directions on the label. In the online survey, some products gave no concentration, and most product pages showed no sun warning. [5] A rinse-off cleanser stays on far more briefly than a leave-on toner or serum, and one glycolic acid product per routine is enough.
In practice, keep it closed in its original packaging, somewhere cool and away from light. Do not mix it with other acids, and check the pack symbol for how long it lasts once opened.
Frequently asked questions
Can you use glycolic acid while pregnant?
Our sources do not answer this directly, so decide with your clinician. The studies in this guide were not designed to assess pregnancy safety, so we call glycolic acid neither safe nor unsafe in pregnancy. Ask separately about the percentage, the area and any in-office peels.
Is glycolic acid suitable for rosacea-prone skin?
Not without your dermatologist’s input. A review lists rosacea among conditions where hydroxy acids are used, but none of our sources tested glycolic acid on rosacea. [6] Since it can cause quick redness, first find out what is behind your flushing; see the facial redness guide.
Should you apply glycolic acid before or after a shower?
After, on clean, dry skin, is the usual practical choice. No study in our sources tested timing around a shower. Apply leave-on products once your face is dry, and use a glycolic acid cleanser in the shower only as its label directs.
References
- Babilas P, Knie U, Abels C. Cosmetic and dermatologic use of alpha hydroxy acids. J Dtsch Dermatol Ges. 2012;10(7):488-491. PubMed · DOI
- Stiller MJ, Bartolone J, Stern R, 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. Arch Dermatol. 1996;132(6):631-636. PubMed
- 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;10(3):202-209. PubMed · DOI
- Kaidbey K, Sutherland B, Bennett P, et al. Topical glycolic acid enhances photodamage by ultraviolet light. Photodermatol Photoimmunol Photomed. 2003;19(1):21-27. PubMed · DOI
- Krstonošić V, Ćirin D. Are cosmetics based on alpha hydroxy acids safe to use when purchased over the internet? Toxicol Ind Health. 2022;38(12):835-838. PubMed · DOI
- Kornhauser A, Coelho SG, Hearing VJ. Applications of hydroxy acids: classification, mechanisms, and photoactivity. Clin Cosmet Investig Dermatol. 2010;3:135-142. PubMed · DOI
- Effendy I, Kwangsukstith C, Lee JY, Maibach HI. Functional changes in human stratum corneum induced by topical glycolic acid: comparison with all-trans retinoic acid. Acta Derm Venereol. 1995;75(6):455-458. PubMed · DOI
- Sharad J. Glycolic acid peel therapy - a current review. Clin Cosmet Investig Dermatol. 2013;6:281-288. PubMed · DOI
- Ditre CM, Griffin TD, Murphy GF, et al. Effects of alpha-hydroxy acids on photoaged skin: a pilot clinical, histologic, and ultrastructural study. J Am Acad Dermatol. 1996;34(2 Pt 1):187-195. PubMed · DOI
- Sarkar R, Lakhani R. Chemical Peels for Melasma: A Systematic Review. Dermatol Surg. 2024;50(7):656-661. PubMed · DOI
- Lim JT, Tham SN. Glycolic acid peels in the treatment of melasma among Asian women. Dermatol Surg. 1997;23(3):177-179. PubMed · DOI
- Erbağci Z, Akçali C. Biweekly serial glycolic acid peels vs. long-term daily use of topical low-strength glycolic acid in the treatment of atrophic acne scars. Int J Dermatol. 2000;39(10):789-794. PubMed · DOI
- Almeman AA. Evaluating the Efficacy and Safety of Alpha-Hydroxy Acids in Dermatological Practice: A Comprehensive Clinical and Legal Review. Clin Cosmet Investig Dermatol. 2024;17:1661-1685. PubMed · DOI
- Lin L, Chen X, Liu C, et al. Comparative efficacy of topical interventions for facial photoaging: a network meta-analysis. Sci Rep. 2025;15(1):26889. PubMed · DOI
