What Is Lactic Acid?

FDA regulations at 21 CFR 184.1061 say lactic acid occurs naturally in several foods and is produced commercially either by fermentation of carbohydrates such as glucose, sucrose or lactose or by a chemical synthesis procedure, and affirm it as generally recognized as safe as a direct human food ingredient used with no limitation other than current good manufacturing practice.

In skin care, the FDA says the most common alpha hydroxy acids (AHAs) in cosmetic products are glycolic acid and lactic acid. It recommends that cosmetics containing an AHA carry a sunburn alert saying the product may increase the sensitivity of the skin to the sun and particularly the possibility of sunburn, and advising users to use a sunscreen, wear protective clothing and limit sun exposure while using the product and for a week afterwards. The FDA reports that the Cosmetic Ingredient Review Expert Panel concluded that products containing glycolic and lactic acid are safe for use by consumers if the AHA concentration is 10 percent or less, the final product has a pH of 3.5 or greater, and the product protects the skin from increased sun sensitivity or its package directions tell consumers to use daily sun protection.

A 2024 review in Physiological Research says muscles increase lactate production as exercise intensity escalates, as a protective mechanism that helps remove excess protons from active muscle fibers, stabilize their pH and sustain muscle contraction, and that contrary to the misconception that lactate induces fatigue, it is an essential element of the adaptive response of the body to strenuous exercise.