Lactic Acid

Lactic Acid is an alpha hydroxy acid (AHA) found naturally in sour milk, fermented foods, and human skin. In hair care, it functions as a pH adjuster, gentle exfoliant, and humectant. It is gentler than glycolic acid and provides mild exfoliation while also attracting moisture. It is commonly used in scalp treatments and pH-balancing formulations.

Source: Fermentation of sugars by Lactobacillus bacteria, or synthesized

Origin: Natural

Also known as: Milk Acid, L-Lactic Acid, DL-Lactic Acid, E270

Lactic Acid gently dissolves the bonds between dead skin cells on the scalp surface, promoting a healthy scalp turnover rate. It maintains product pH in the optimal acidic range for hair health and acts as a humectant, drawing moisture to the hair and scalp. It is particularly effective in scalp serums and exfoliating treatments.

Best For

Dry scalp, flaky scalp, dull hair, all hair types (as pH adjuster), aging scalp

Not Recommended For

Very sensitive scalp at high concentrations, compromised skin barrier

Concentration Matters

0.1-5%

Very safe at cosmetic concentrations (under 5%). Can cause mild stinging or irritation at higher concentrations. UV sensitivity may increase with regular use, though this is mainly a skin concern. Gentle enough for most sensitive scalps at low concentrations.

FDA Status: Generally Recognized As Safe

FDA classifies as GRAS for food use. Used in OTC skin products. Permitted in cosmetics without specific restrictions.

EWG Score: 1/10

Scalp treatments, pH-adjusting products, gentle exfoliating treatments, conditioners

If you want to avoid Lactic Acid, look for products with these ingredients instead:

Citric Acid, Glycolic Acid, Mandelic Acid, Salicylic Acid