Nioxin system 4 scalp treatment provides denser-looking hair while protecting the scalp. For noticeably thinning, fine, chemically-treated hair. How To Use: Apply directly to the entire scalp. Gently massage into scalp. Do not rinse. Use daily. It may cause temporary redness to the scalp after application. Please be aware ingredients are subject to change periodically. It is recommended you check the product packaging prior to use for a complete ingredient list.