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Glycolic Acid in skincare
Smallest AHA; deep exfoliation, collagen stimulation, and brightening.
Strongly preferred for PM use only. Glycolic acid degrades under UV and significantly increases photosensitivity. Applying in the AM without SPF (and even with SPF) increases erythema and photoaging risk. If AM use is unavoidable (toner at low %, rinse-off), always follow with SPF 30+. PM use is optimal. Skin's natural repair cycle and absence of UV exposure maximize efficacy and safety.
What it is
Glycolic Acid (from sugar cane) has the smallest molecular weight of all AHAs (76 Da), enabling the deepest epidermal penetration. Optimal pH for activity: 3.0–4.0. At pH >4, efficacy decreases. FDA endorses 10% for OTC use; professional peels use 20–70%. Mandatory sunscreen with AHA use. EU Cosmetics Regulation requires AHA-containing products to carry UV warning. Introduce gradually.
The facts
| Category | AHA (Alpha Hydroxy Acid) |
| Typical use | Evening |
| Concentration YARAI treats as a full dose | 10% |
Why the amount matters, not just the presence
Most ingredient checkers tell you whether something is in the bottle. That is a smaller question than it sounds. Glycolic Acid at 10% and glycolic acid at a trace level are not the same ingredient in any way that affects your skin.
An ingredient list is ordered by quantity, so position carries real information. YARAI reads that position and scores accordingly, which is why the same ingredient can land differently in two different products.
The honest limit: a list gives order, not percentages. Estimating concentration from position is an estimate. It is a better estimate than ignoring position, and it is still an estimate. We would rather tell you that than let a number look more certain than it is.
Using it with something else
Glycolic acid appears in 4 of the pairs YARAI checks. Each page gives the severity, the chemical mechanism, the evidence tier and the source:
- Can you use retinol and glycolic acid together?
- Can you use benzoyl peroxide and glycolic acid together?
- Can you use niacinamide with AHA or BHA acids?
- Can you use copper peptides with vitamin C or acids?
Common questions
What does glycolic acid do in a skincare product?
Smallest AHA; deep exfoliation, collagen stimulation, and brightening.
How much glycolic acid should a product contain?
YARAI treats 10% as a full dose for this ingredient. Below that, the ingredient is present but is scored as contributing less. An ingredient list gives you the order of ingredients, not their percentages, so this is an estimate read from position rather than a measurement.
When should I use glycolic acid?
Strongly preferred for PM use only. Glycolic acid degrades under UV and significantly increases photosensitivity. Applying in the AM without SPF (and even with SPF) increases erythema and photoaging risk. If AM use is unavoidable (toner at low %, rinse-off), always follow with SPF 30+. PM use is optimal. Skin's natural repair cycle and absence of UV exposure maximize efficacy and safety.
Check your own products
Point your camera at a product. YARAI identifies it from the label, finds that product's full ingredient list from published sources, and scores it. No barcode and no box needed, which is how it handles imported and small-brand products.
Concern level, category and thresholds on this page are read directly from the same data the YARAI app scores with, so this page and the app cannot disagree. EU figures cite Regulation (EC) No 1223/2009. Last built 2026-10-12. Nothing here is medical advice.