Ingredient Beauty BenefitsTexture and flaking
Built-up dead cells and rough skin surface.
Texture is the concern where concentration and pH completely override the name of the ingredient.
Urea is the most extreme case. At low concentrations it holds water; at 20–40% it dissolves keratin. Same name, different object.
And with acids the label gives you a hint. A Korean notice fixes the wording for AHA-containing products, so the line advising you to consult a specialist means the product is above 10% or below pH 3.5. The glycolic acid page explains it in detail. Gluconolactone, though, does not carry that line — because it is not an AHA.
Salicylic acid
Salicylic Acid
Most acne trials used 30% peels performed in a clinic. What Korea allows as an acne functional claim is 0.5%, and only in rinse-off cleansers. There is a sixtyfold gap between those two numbers.
Glycolic acid (AHA)
Glycolic Acid
In a 22-week, 74-person, vehicle-controlled double-blind trial, **76% of people using 8% glycolic acid cream improved by at least one grade of photodamage** (vehicle: 40%). Thirty years on, we found nothing better for this ingredient. And the same molecule **did not protect the skin barrier.**
Urea
Urea
**5% and 40% are effectively different products.** At low concentrations it holds water; at high concentrations it dissolves keratin. A 40% cream beat 12% ammonium lactate at two weeks, and in a 167-person trial of a urea-containing cream **the primary endpoint was missed** (P = .088) while the other measures were significant.
Gluconolactone (PHA)
Gluconolactone
A 1997 trial put four acids side by side and then challenged the skin. **Sites treated with gluconolactone lost significantly less barrier function than vehicle, than untreated skin, and than glycolic acid.** And the Korean AHA warning text does not apply to this ingredient.
Lactic acid
Lactic Acid
In a 1983 trial, a 12% lactate lotion, a 5% lactic acid lotion and a plain emollient **all three** significantly improved xerosis. The difference emerged **one to two weeks after treatment stopped.** And in the 1996 photodamage trial it beat vehicle on four forearm measures — more than glycolic acid managed in the same trial.
Clinical procedures related to this concern
Procedures are not listed alongside topical ingredients. They are not something you use at home.
- Fractional laser (Fraxel, fractional CO2) Device-based
- Microneedling (dermapen, dermaroller) Device-based