Glycolic Acid
The smallest and most penetrating alpha-hydroxy acid (AHA). Derived from sugarcane, glycolic acid exfoliates by dissolving the bonds between dead skin cells on the surface, revealing smoother, brighter skin underneath. It is the most studied AHA with robust evidence for improving texture, fine lines, hyperpigmentation, and overall skin radiance. The gold standard chemical exfoliant.
Concentration & Usage
Daily use: 5-10% at pH 3-4. Weekly peel: 10-30%. Professional peel: 30-70%. Start with 5% every other night. Increase concentration/frequency gradually. Always use SPF — AHAs increase sun sensitivity by up to 50%. Buffered formulations are gentler than free acid.
Application
Topical (toner, serum, peel, cleanser). Leave-on products are more effective than wash-off. Apply to dry skin at night.
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Mechanism of Action
Glycolic acid disrupts ionic bonds between corneocytes (dead skin cells) in the stratum corneum by chelating calcium ions and lowering the calcium concentration at desmosomal junctions. This weakens corneodesmosome integrity and activates endogenous proteases (kallikrein 5 and 7), accelerating desquamation. At higher concentrations, glycolic acid penetrates the viable epidermis and dermis, where it stimulates keratinocyte differentiation and upregulates transforming growth factor-beta (TGF-β) signaling in fibroblasts. This promotes glycosaminoglycan (GAG) synthesis, type I and III collagen production via procollagen gene expression, and elastin remodeling. Its small molecular size (76 Da) and high water solubility give it the deepest penetration of any AHA. The exfoliation also improves barrier function over time by promoting proper corneocyte maturation and reducing stratum corneum compaction.
Ingredient Interactions
Apply glycolic acid first, let it absorb, then follow with niacinamide. The niacinamide soothes irritation and provides brightening through a complementary mechanism.
Using both AHA and BHA in the same routine over-exfoliates most skin types. If you want both, use them on different days. Some people with oily, resilient skin can tolerate a gentle version of both, but start cautiously.
There is no benefit to layering two AHAs. Pick one based on your skin type: glycolic for oily/resilient skin, lactic for dry/sensitive skin. Using both is redundant and increases irritation.
Glycolic acid lowers skin pH and increases hydroquinone penetration, which can boost efficacy but also irritation. Start with lower concentrations and introduce slowly.
Urea at 10%+ has keratolytic (exfoliating) properties similar to AHAs. Combining with glycolic acid can over-exfoliate. Use one or the other, or use low-concentration urea (under 5%) with AHA.
Both retinol and glycolic acid increase cell turnover. Using them together can cause excessive dryness, peeling, and barrier damage. Use glycolic acid in the morning or on alternate nights from retinol.
Tretinoin is more potent than retinol — combining with glycolic acid significantly increases irritation, peeling, and barrier damage. Use glycolic acid on non-tretinoin nights or in the morning.
L-ascorbic acid and glycolic acid both require low pH. Layering them can cause irritation and stinging. Use vitamin C in the AM (pairs with sunscreen) and glycolic acid at PM.
See our full Ingredient Interactions Guide for more combinations and timing strategies.
Regulatory Status
Cosmetic ingredient at concentrations up to 10% (OTC). Higher concentrations are professional-use only or prescription. FDA safety guidance limits OTC AHAs to 10% at pH 3.5+.
Risks & Safety
Common
Stinging, redness, peeling, sun sensitivity. Over-exfoliation damages the skin barrier.
Serious
Chemical burns from professional-strength peels without proper protocol.
Rare
Scarring from improper high-concentration use.
Compare Glycolic Acid With
Research Papers
9Published: January 17, 2024
AI Summary
Superficial chemical peels are one of the most popular skin resurfacing procedures in a dermatologists' clinic today due to quick application process, fast recovery, good patient acceptance, and excellent cosmetic results.
Published: August 10, 2019
AI Summary
Over the last 30 years, the science behind chemical peeling has evolved, increasing our understanding of the role of peeling ingredients and treatment indications. The depth of peels is directly related to improved results and to the number of complications that can occur.
Published: November 2, 2021
AI Summary
The treatments for hyperpigmentation disorders often take very long to show results and have poor patient compliance. These shortcomings of the conventional treatments provided scope for further research on newer alternatives for managing hyperpigmentation.
Published: April 9, 2018
AI Summary
The aim of this manuscript is to review the various biological effects and mechanisms of AHAs on human keratinocytes and in an animal model. These mechanisms of AHAs are currently well understood, aiding the development of novel approaches for the prevention of UV-induced skin damage.
Published: September 11, 2023
AI Summary
The absence of any change in the R after the CGG application indicates that it does not affect the skin transmission, or cause distortion, microdamage or changes in ion permeability. However, the reduction in potential may be due to the increased transport of chloride ions, and thus water, from outside the cell into the cell interior.
Published: January 25, 2007
AI Summary
Combining procedures can enhance the overall result and lead to increased patient satisfaction. Fillers or botulinum toxin type A (BTX-A) can plump the skin and smooth lines and wrinkles but will do little for uneven tone, skin laxity, or radiance and clarity.
Published: June 5, 2024
AI Summary
Our findings reveal time-specific responses of key proteins to GA: Filaggrin, Involucrin, Loricrin, and Ki67 showed very early responses; KLK10 an early response; and AQP3 and K10 late responses. Our results offer insights for designing interventions to mitigate GA's adverse effects on skin, enhancing the safety and efficacy of GA peeling treatm...
Published: March 1, 2021
AI Summary
Improvement in skin luminosity and dyschromia such as postinflammatory hyperpigmentation (PIH) and actinic photodamage are leading causes for cosmetic consultation. Formulation of topical at home treatment is challenging, using a range of modalities, to help hinder or prevent inflammatory mediators without further irritating the skin.
Frequently Asked Questions
What is Glycolic Acid used for?
The smallest and most penetrating alpha-hydroxy acid (AHA). Derived from sugarcane, glycolic acid exfoliates by dissolving the bonds between dead skin cells on the surface, revealing smoother, brighter skin underneath. It is the most studied AHA with robust evidence for improving texture, fine lines, hyperpigmentation, and overall skin radiance. The gold standard chemical exfoliant.
What are the side effects of Glycolic Acid?
Common: Stinging, redness, peeling, sun sensitivity. Over-exfoliation damages the skin barrier. Serious: Chemical burns from professional-strength peels without proper protocol. Rare: Scarring from improper high-concentration use.
How is Glycolic Acid administered?
Glycolic Acid is administered via topical (toner, serum, peel, cleanser). leave-on products are more effective than wash-off. apply to dry skin at night..
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