Lactic Acid

What is lactic acid and what does it do?

Lactic acid is an alpha hydroxy acid found naturally in the body and in fermented milk. Its molecules are larger than glycolic acid, so it penetrates more slowly and is often gentler. At low concentrations it acts as a humectant, attracting water into the outer skin layer, and it is a component of the skin's natural moisturising factor; this is why it appears in moisturisers for dry, rough skin and keratosis pilaris. At higher concentrations it loosens the bonds between dead cells, improving texture and dullness and helping fade superficial pigmentation. It also makes skin more sensitive to sunlight while in use. [1]

What does the evidence show?

Reviews of alpha hydroxy acids report improvement in dryness, roughness, superficial pigmentation and photoaging, but much of the clinical evidence comes from small or older studies, often combining several AHAs. Lactic acid-containing moisturisers are established for dry, scaly skin. Evidence specific to lactic acid peels is limited compared with glycolic acid. It is better regarded as a gentle exfoliating and moisturising option rather than a corrective treatment.

Who should avoid lactic acid?

Those with eczema flares, rosacea, sunburn or broken skin should avoid it, as it can sting. People with very sensitive skin may react even to low strengths. Darker skin types should introduce it gradually to reduce the risk of irritation-related pigmentation. Avoid combining with other exfoliants on the same day when starting.

Is lactic acid available in Singapore?

Lactic acid is a common cosmetic ingredient in Singapore, found in cleansers, serums and moisturisers, and in some medicated moisturisers for dry skin. Higher-strength peels are intended for professional use. Strength and pH determine how a product acts, so if unsure, check with a doctor or pharmacist.

If a dark patch, breakout or irritation is not responding to what you are using, the next step is a diagnosis rather than another product. See the Skin A–Z library for related ingredients.