A protein commonly found in milk. It is used in cheesemaking, paint manufacturing, cosmetics, and in a number of other applications.

Condom manufacturers sometimes use casein to produce latex. Because casein is usually derived from dairy milk, this can be an important distinction for vegans. Vegan-friendly condoms do not use casein, milk-derived substances, or any other animal products in their production.

Some people are allergic to casein and should avoid products that use this protein. However, allergies are relatively rare.