Sodium Lactate
Also known as Sodium L-lactate, Lactic acid sodium salt, Sodium 2-hydroxypropanoate
“CIR Expert Panel says: safe within use limit.”
Sodium Lactate (CAS 72-17-3) is the sodium salt of lactic acid and a primary endogenous component of the skin's Natural Moisturizing Factor (NMF). Peer-reviewed studies confirm that lactate levels in the stratum corneum correlate directly with hydration state, stiffness, and pH in healthy subjects (PMID 15086563), and that topical potassium lactate application restores hydration in atopic dermatitis patients with depleted NMF (PMID 22464763). At humectant-range concentrations typical in cosmetics (typically 1–5%), sodium lactate functions by binding water in the stratum corneum. At higher AHA-group concentrations (up to 10% leave-on, 30% salon), it shares the CIR group assessment for glycolic and lactic acid salts, which requires sun-sensitivity labelling and pH control.
Primary endogenous NMF component: lactate and potassium are the only NMF constituents found to correlate significantly with stratum corneum hydration state, stiffness, and pH in healthy subjects
Topical application of potassium/sodium lactate restores stratum corneum hydration depleted by NMF extraction or in mild atopic dermatitis
Well-tolerated humectant with a long history of use across moisturisers, toners, and barrier-repair products; naturally occurring metabolite with no systemic toxicity at cosmetically relevant exposures
CIR group assessment:1-242, 1998) covers lactic acid, glycolic acid, their common salts and simple esters — sodium lactate is directly named as a covered ingredient
- · The CIR SQ finding sets a 10% leave-on limit at pH>=3.5; at salon concentrations up to 30% (pH>=3.0), brief-contact use by trained professionals is required
- · At humectant-typical concentrations (1–5%), pH control is not typically a concern; the AHA restrictions become material at exfoliant-active concentrations
As a lactic acid salt assessed under the CIR AHA group:1-242, 1998), sodium lactate carries the same sun-sensitivity labelling requirement as lactic acid at concentrations above the typical humectant range: formulations must either avoid increasing sun sensitivity or include directions for daily sun protection
CIR Quick Reference Table (12/2017, revised 07/2018) — Sodium Lactate row: Finding=SQ, Citation=IJT 17(S1):1-242, 1998
“Sodium Lactate SQ safe for use in cosmetic products at concentrations less than or equal to 10%, at final formulation pH greater than or equal to 3.5, when formulated to avoid increasing sun sensitivity or when directions for use include the daily use of sun protection. safe for use in salon products at concentrations less than or equal to 30%, at final formulation pH greater than or equal to 3.0, in products designed for brief, discontinuous use followed by thorough rinsing from the skin, when applied by trained professionals, and when application is accompanied by directions for the daily use of sun protection. IJT 17(S1):1-242, 1998”— QRT-122017revised072018.pdf, p. 120