Proteins have been an important category in cosmetics since the inception of the beauty product industry. Cosmetics were originally designed and categorized as formulations that temporarily enhance the appearance of the skin, hair, or nails. In contrast to drugs, which are strictly tested, controlled, and distributed, cosmetics are meant to adorn rather than alter biological structure or function of the skin. Kligman suggested a hybrid category to better classify formulations that have not been tested as drugs, but clearly exhibit clinical effects beyond that of mere skin hydration or temporary adornment. The resulting cosmeceutical industry has grown at an astonishing rate.