What it is
Lactose is a disaccharide sugar composed of glucose and galactose, best known as the principal sugar found in milk. In cosmetics it functions as a skin-conditioning agent and can contribute humectant character, and it sometimes appears as a substrate or component within ferment-based formulas. In sunscreens it plays a supporting conditioning role and does not contribute to UV protection.
Safety & warnings
Lactose used topically is generally well tolerated; topical use is unrelated to dietary lactose intolerance, which concerns digestion of the sugar when consumed.
Origin & sourcing
Naturally occurring; classically obtained from milk, and also produced as a purified sugar for industrial and cosmetic use.
Questions everyone asks
Is topical lactose a problem for people who are lactose intolerant?
Lactose intolerance concerns digestion of the sugar when eaten and is not the same as applying it to the skin.
What does lactose do in a formula?
It acts as a skin-conditioning, humectant-type sugar and can serve within ferment systems.