What is it?
The sodium salt of lactic acid, made by neutralizing lactic acid with sodium hydroxide. It is a humectant: it attracts and holds water, and it occurs naturally in the skin’s outer layer, where it is among the most water-attracting components. In skin and hair care it is used to add moisture and to buffer pH, sometimes alongside lactic acid. It is also a common food additive, listed as E325.
Key information
- Sodium lactate is the sodium salt of lactic acid and works mainly as a humectant and pH buffer.
- It occurs naturally in the outer layer of the skin, where it is among the most water-attracting substances.
- The CIR Expert Panel's conclusion for lactic acid and its common salts, including sodium lactate, is safe at up to 10 percent at pH 3.5 or higher, with conditions on sun sensitivity.
- The FDA affirms sodium lactate as generally recognized as safe (GRAS) as a food ingredient.
More information
Sodium lactate is prepared commercially by neutralizing lactic acid with sodium hydroxide. In the skin, lactate is one of the natural water-holding substances in the outermost layer, the stratum corneum; the Cosmetic Ingredient Review (CIR) notes that PCA and sodium lactate make up its most hygroscopic, or water-attracting, fraction. In cosmetics it is used for that same water-holding property.
The CIR Expert Panel reviewed lactic acid together with its common salts, including sodium lactate. It concluded they are safe in consumer products at concentrations of 10 percent or less and a final pH of 3.5 or higher, when formulated to avoid increasing sun sensitivity or when directions call for daily sun protection. The sun-sensitivity and stinging concerns with alpha hydroxy acids are tied to acidity: the EU’s former cosmetics safety committee (SCCNFP) noted that AHAs promote skin cell turnover most effectively in their un-ionized, acid form, and that pH is the most important factor in how irritating they are. Sodium lactate is the neutralized salt, so on its own it acts mainly as a moisturizer and buffer rather than an exfoliant.
As a food ingredient, the FDA affirms sodium lactate as generally recognized as safe (GRAS) for uses that include humectant and pH control agent. On labels it appears as sodium lactate. If lactic acid is also listed, the two may be working as a buffer, and the product’s pH will largely decide how exfoliating it is.
Sources: Cosmetic Ingredient Review: Quick reference table of ingredient findings (September 2020); Code of Federal Regulations, 21 CFR 184.1768 (via Cornell LII): Sodium lactate; Cosmetic Ingredient Review: Safety assessment of PCA (2-pyrrolidone-5-carboxylic acid) and its salts as used in cosmetics, final amended report (2015); European Commission SCCNFP: Position paper concerning the safety of alpha-hydroxy acids (2000)
