ABSTRACT
Unlike other pigmented cosmetics products, lip formulations are applied directly to a mucous membrane. Therefore, they must be toxicologically innocuous. They are tasted continuously and, due to close proximity of the upper lip and the nose, are smelled readily as well. Because the lips and surrounding tissues are highly innervated, it is particularly important for lip cosmetics to exhibit smooth application and emollient textures. In addition to embellishing the surfaces of the lips, lip products also provide moisturization and can act as a barrier against chapping. Many lip products also incorporate sunscreen actives, to protect lip tissue from UV attack.
