Lactose is a naturally occurring simple carbohydrate, or sugar, found only in the milk of mammals. For this reason, it is also commonly referred to as “milk sugar.” All commercial lactose is obtained from the milk of cows as a by-product of the dairy industry. Chemically, lactose is the disaccharide of the simple sugars D-galactose and D-glucose.

Lactose is widely used as a filler or filler-binder in the manufacture of pharmaceutical tablets and capsules and other products.