This Cleansing Shampoo is specifically formulated as part of the Nioxin System 4 regimen, designed for hair that is fine and has become significantly thinning, particularly if it is colored or chemically treated. It effectively cleanses the scalp and hair, helping to remove sebum, fatty acids, and environmental residues that can clog follicles. By providing a clean foundation, this shampoo prepares the hair to better absorb subsequent treatment steps in the system, promoting thicker-looking hair. Use this shampoo as the first step in your daily or thrice-weekly Nioxin System 4 routine for optimized results.