Glycolic Acid
Alpha-hydroxy acid (AHA) with the smallest molecular weight in the group. Accelerates desquamation, evens skin tone and texture.
Evidence by route
Topical application
One of the most extensively studied AHAs. RCTs and systematic reviews confirm efficacy for acne, melasma, photoaging, and keratosis. Professional peels at 20–70% concentrations have extensive clinical evidence.
- Sharad J et al. Clin Cosmet Investig Dermatol. 2013;6:281-8. PMID 24399880
- Tang SC et al. Molecules. 2018;23(4):. PMID 29642579
How to read tiers A–F
- AProven efficacy. Two or more independent RCTs with instrumental endpoints
Tolerability and safety
- Working concentrations
- 1–10% in leave-on products; 20–70% peels – professional use only
- Irritation potential
- Medium
- Allergen risk
- Low
- Pregnancy
- Safe
- Suitable for
- Normal, Combination, Oily
- Use with caution
- Sensitive, Dry
For sensitive skin
Risk of burning and irritation with prolonged contact. Products containing glycolic acid require daily SPF30+ sun protection.
Combinations with other ingredients
Does not combine with
Salicylic Acid
Two acid exfoliants at once are excessive. Alternate: AHA one evening, BHA another, to avoid barrier overload.
Retinol
Using both in one routine raises irritation 2-3x. Alternate: retinol at night, AHA on a different evening.
Niacinamide
When combined in one formula, niacinamide can convert to nicotinic acid (flush, redness). Rare in modern leave-on, but alternating is safer.
About this ingredient
Glycolic Acid (Hydroxyacetic Acid) is an alpha-hydroxy acid (AHA) with the smallest molecular weight in this group (76 Da). Obtained from sugarcane or synthetically. The deepest-penetrating AHA – active in the dermis at the right concentration and pH. Mechanism. Dissolves the corneocyte bonds of the stratum corneum – accelerates desquamation. Stimulates collagen and glycosaminoglycan synthesis in the dermis (Bernstein 2001), reduces hyperpigmentation, evens texture. Where applied. OTC serums and toners (5-10%, pH 3.5-4), professional peels (20-70%, pH 1.5-3). Brands include The Ordinary Glycolic Acid 7%, NeoStrata, Pixi Glow Tonic, Spanish Sesderma Acglicolic, Mesoestetic Glycolic Acid. Evidence base. AAD 2024 and Cochrane 2020 classify glycolic acid as first-line for photoaging, post-acne marks, melasma, hyperkeratosis. Sharad 2013 in 50 women over 12 weeks of 10% glycolic acid: texture, tone, wrinkle improvement in 80% of participants. Safety. CIR/SCCS confirm safety up to 10% OTC at pH ≥ 3.5, up to 70% in professional peels under dermatologist supervision. Irritation, peeling, and erythema in the first 1-2 weeks in 30-50% of patients. Photosensitizes – daily SPF 30+ mandatory. Pregnancy – safe at OTC concentrations (SAFE per SEGO 2023). Deep professional peels (>30%) are postponed in pregnancy. Lactation – use with caution: avoid breast application. Suitable for. Photoaging, post-acne marks, melasma, uneven texture, follicular hyperkeratosis. Not suitable: sensitive skin, active rosacea, eczema, dermatitis. Alternative – PHA (gluconolactone).
Frequently asked questions
Is Glycolic Acid safe during pregnancy?
Glycolic Acid is considered safe during pregnancy at typical cosmetic concentrations. Systemic absorption through the skin is minimal.
What skin types is Glycolic Acid for?
Glycolic Acid suits: normal, combination, oily. Use with caution in: sensitive, dry.
Can Glycolic Acid irritate the skin?
Glycolic Acid has moderate irritation potential. Sensitive skin may show a transient reaction that usually settles with adaptation.
What is Glycolic Acid and what does it do in cosmetics?
Alpha-hydroxy acid (AHA) with the smallest molecular weight in the group.
What's the INCI name for Glycolic Acid?
The INCI name is Glycolic Acid. It may also appear as: Hydroxyacetic Acid.
What concentration of Glycolic Acid is effective?
1–10% in leave-on products; 20–70% peels – professional use only
See Glycolic Acid in a product composition right on the store page
The Evigrade extension adds an evidence panel to iHerb, Sephora, Druni and 12 more stores. This ingredient and every other one in the product show evidence-tier, allergen risk and pregnancy/lactation flags at a glance.
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