This Nioxin System 4 Cleanser Shampoo is professionally formulated to thoroughly cleanse the scalp and hair, removing product buildup, excess sebum, and environmental pollutants that can clog follicles. It is the first step in the Nioxin 3-Part System designed for noticeably thinning, fine hair that is chemically treated. It prepares the hair and scalp environment for advanced treatment adherence, promoting thicker, fuller-looking hair by delivering essential nourishment where it is needed most.