Lactic acid
INCI Lactic Acid
A gentle alpha hydroxy acid that loosens dull surface cells while drawing in water. Smoother texture and a brighter look, with less sting than glycolic.
- Typical use range
- 5–10% per the literature, not our formula
- Also known as
- L-Lactic acid, 2-Hydroxypropanoic acid, AHA
- Identifiers
- PubChem CID 612
Lactic acid is an alpha hydroxy acid (AHA) and, like PCA, a component of the skin's natural moisturising factor. Its molecule is larger than glycolic acid's, so it moves into the skin more slowly. In practice that means a milder, more predictable exfoliation and a lower likelihood of stinging.
At the surface it loosens the bonds holding dull, dead cells in place so they shed more evenly. The result over a few weeks is smoother texture, a brighter look and a more even-looking tone. Unusually for an exfoliant it is also a humectant, so a well-formulated lactic acid product leaves the skin feeling hydrated rather than tight.
The Cosmetic Ingredient Review concluded that AHAs are safe in consumer leave-on products at up to 10% at a pH of 3.5 or higher, with directions for daily sun protection. Exfoliating acids increase sun sensitivity, so a broad-spectrum sunscreen every morning is part of using them properly.
Where you will find it.
- Multi-Active Complex Face Serum Serum In the INCI
Percentages are read from each product's stated active complex. Where none is stated the ingredient appears in the full INCI only.
Can I use lactic acid with retinol?
On alternate evenings rather than together. Both increase cell turnover, and stacking them raises the chance of irritation without improving results.
Why does the formula's pH matter?
An AHA is active only in its free-acid form, which depends on pH. Too high and it does little; too low and it stings. We formulate in the range where it works and stays comfortable.
Is lactic acid suitable for sensitive skin?
It is the gentlest of the common AHAs, but sensitive skin should still start with every other evening and patch-test first.
- CosIng, Lactic Acid (EU cosmetic ingredient database) ec.europa.eu/growth/tools-databases/cosing/
- PubChem, Lactic acid (CID 612) pubchem.ncbi.nlm.nih.gov/compound/612
- Cosmetic Ingredient Review. Final report on the safety assessment of glycolic acid, lactic acid and their salts and esters. Int J Toxicol. 1998;17(Suppl 1):1–241.
- US FDA. Guidance for industry: labeling for cosmetics containing alpha hydroxy acids.