Lactose monohydrate refers to lactose containing one crystal water, and its molecular structure is a dimer of D-galactose and D-glucose, in which D-galactose and D-glucose are connected by �²-1,4-glycosidic bonds and form a monohydrate by intramolecular hydrogen bonds.

Lactose monohydrate is widely used in the fields of medicine, cosmetics and food. In the field of medicine, it is used as a filler and diluent for tablets and capsules, and is also used as a diluent for dry powder inhalers; in the field of cosmetics, lactose monohydrate is often used as a formula ingredient for cosmetics such as creams and lotions, and has moisturizing and softening effects; in the field of food, lactose monohydrate is usually used to make chocolate, candy, biscuits, baked goods, etc., and has become an ideal ingredient in the food industry due to its high sweetness and high solubility.