Carboxymethyl cellulose(CMC) or cellulose gum is a cellulose derivative with carboxymethyl groups (-CH2-COOH) bound to some of the hydroxyl groups of the glucopyranose monomers that make up the cellulose backbone. It is often used as its sodium salt, sodium carboxymethyl cellulose.
CMC is used in food under the E number E466 as a viscosity modifier or thickener, and to stabilizeemulsions in various products including ice cream. It is also a constituent of many non-food products, such as toothpaste, laxatives, diet pills, water-based paints, detergents, textile sizing, and various paper products.
CMC is also used in pharmaceuticals as a thickening agent, for example as the lubricant in lubricating eye drops, and in the oil-drilling industry as an ingredient of drilling mud, where it acts as a viscosity modifier and water retention agent.