Cellulose is often used as its sodium salt, sodium carboxymethyl cellulose, as a viscosity modifier or thickener, and to stabilize emulsions 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, and various paper products. It is used primarily because of it has high viscosity, is non-toxic, and is generally non-allergenic. CMC is used as a lubricant in non-volatile eye drops (artificial tears).