Ingredient glossary
Glycolic acid
On your shelf ✓What Glycolic acid does for your skin, who it suits, and what to watch for.
INCI: Glycolic Acid · Also: AHA
In short: Glycolic acid delivers exfoliation and anti-aging support, suits most skin types, and the evidence behind it is strong. One thing to know: clear it with your doctor if pregnant; can irritate, ease in slowly.
- What it does
- Exfoliation, anti aging
- Best for
- Most skin types
- Watch out
- Clear it with your doctor if pregnant; can irritate, ease in slowly
- Evidence
- Strong
- How long
- 3 months+
how it was measured
Measured on investigator-graded overall severity of photodamage, a 0-9 composite; sallowness is the only individual sign that separated for glycolic acid, and only on the forearm; measured at the trial's end, so possibly sooner.PMID 8651713PMID 8642081
The molecule
The Glow take
One of the ingredients I trust most.
When your goal is softening fine lines and keeping skin firm, Glycolic acid delivers, and the research properly backs it up. It can sting a fresh or sensitive barrier, so start a couple of nights a week and always patch test first.
— Maya
What it does
- exfoliation
- anti aging
strong evidenceSignificant evidence for AHA exfoliation, improving texture, tone and photoaging signs at appropriate pH and strength.
Why we say this
- CIR safety review 40th Anniversary Overview and Rereview Summaries From 2011 to 2015
- CIR safety review Final Report on the Safety Assessment of Glycolic Acid and related ingredients
The AHA family, at a glance
7 AHA entries in the base, Glycolic acid among them. 5 of the 7 are a supporting active.
- Glycolic acid76 Da
- Lactic acid90 Da
- Ammonium lactate107 Da
- Malic Acid134 Da
- Tartaric Acid150 Da
- Mandelic Acid152 Da
- Citric Acid192 Da
How much do you need?
5%+
The vehicle-controlled trials worked from 5%; no published dose comparison sets a ceiling.
The trials, and what they used
- Floor 5%: Unneutralized 5% glycolic acid topical cream when used on a regular daily basis can improve some photoaging effects.
The pH it needs
The un-ionised acid (pKa 3.83) crosses the stratum corneum; in human skin in vitro, 4% at pH 2.0 went in far more than at pH 3.8.
pH 5.0 is outside 3.25 to 4.4, the window the study tested (ichthyotic and xerotic skin); it measured nothing here.
This study reports on the clinical and histological effects of glycolic acid at pH levels 3.25, 3.80, and 4.40, and at 3.25%, 6.50%, 9.75%, and 13.00% on ichthyotic/xerotic skin.
Drag the handle along the line. Only what was measured is drawn; between the marks nothing was. Your skin's surface: about 4.7 at rest, 5.1 on a normal day.PMID 18489300PMID 8634803
Who it's for, and who should skip it
Tends to suit
- normal
- oily
Approach with care
- sensitive
- compromised barrier
- rosacea
- Clogs poresLow
- Irritation riskHigh
- pH-dependentIts effect depends on the product's pH
How it fits each skin type
- DrySuits
- CombinationSuits
- OilySuits
- SensitiveTake care
Take extra care if any of these apply to you: compromised barrier, rosacea.
Where it fits in your routine
Increases sun sensitivity while you are using it, so sunscreen matters more than usual.
Why we say this
- The smallest and most penetrating AHA, and one of the two acids used in the studies behind FDA's recommended sunburn alert, where topical glycolic acid at consumer-product strength measurably lowered the minimal erythema dose.
- No specific percentage is stated here because the exact study concentration could not be verified.
US FDA guidance for industry, labeling for cosmetics containing alpha hydroxy acids (2005), recommended Sunburn Alert statement
Give it three months or more, and possibly less: that is simply when it was measured.
What was measured, and in whom
- Measured on: investigator-graded overall severity of photodamage, a 0-9 composite; sallowness is the only individual sign that separated for glycolic acid, and only on the forearm.
- The controlled leave-on evidence is a 22-week vehicle-controlled trial in 74 women applying 8% glycolic acid twice daily to face and forearms, reporting at its endpoint, so 22 weeks is a ceiling rather than an onset.
- What separated matters as much as when: on the face 76% of the glycolic group gained at least one grade of improvement in overall severity of photodamage against 40% on vehicle, and that composite is the endpoint; on the forearms at week 22 glycolic acid beat vehicle only on overall severity and on sallowness.
- Mottled hyperpigmentation and roughness reached significance in the same trial's L-lactic acid arm, not the glycolic one, and fine wrinkling separated for neither, so none of those three signs may be attached to this row.
- The supporting 25% AHA forearm study ran an average of six months with biopsies taken only at the end.
- In-office peel series are a different exposure entirely — higher strength, short contact, repeated at intervals — and their timelines do not transfer to an 8-10% daily product.
- Reduced corneocyte cohesion begins within days of daily use, but no trial reports that as a timed endpoint.
Stiller MJ, Bartolone J, Stern R, Smith S, Kollias N, Gillies R, Drake LA. 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):631-6. PMID:8651713. Supporting histology: Ditre CM 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):187-95. PMID:8642081 (25% AHA lotion, forearm, average 6 months).
Plays well with
- humectants
- ceramides
Glycolic acid, answered
Is Glycolic acid safe during pregnancy?
Clear it with your doctor first. Glycolic acid is flagged as use-with-caution during pregnancy and breastfeeding, so check with your doctor or midwife before adding it.
Who should avoid Glycolic acid?
Approach Glycolic acid with care if any of these apply to you: sensitive, compromised barrier, and rosacea. Its irritation risk is high, so introduce it slowly and patch test first.
What concentration of Glycolic acid actually works?
Its concentration is rarely printed on the label, so use the ingredient list as your clue: near the top third it is likely doing real work, near the bottom it is more of a sprinkle.
During pregnancy
Treat Glycolic acid as a maybe rather than a yes for now. It is flagged as one to use with caution while pregnant or breastfeeding, so it is worth clearing before you carry on.
When in doubt, check with your doctor or midwife. They outrank any website, including this one.When it is worth booking →
Commonly confused with
- Lactic acidBoth are AHAs. Glycolic is the smaller molecule that gets in deeper and stronger; lactic is gentler and also hydrates.
- Salicylic acid (BHA)Salicylic is oil-loving and works inside the pore (a BHA). Glycolic works on the surface (an AHA).
Readers asked about Glycolic acid
On the map
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Can you mix Glycolic acid with
25 pairings built, the 5 most looked-up above.
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Sources & how we reviewed this
- CIR safety review 40th Anniversary Overview and Rereview Summaries From 2011 to 2015summary page only, the document itself was not read
- CIR safety review Final Report on the Safety Assessment of Glycolic Acid and related ingredientssummary page only, the document itself was not read
What changed on this page
- : the pH it needs
- : the effective dose from trials, the highest dose tested
- : what the EU regulates