SYSTEM 6 - CHEMICALLY TREATED HAIR - FOR PROGRESSIVE THINNING HAIR. Protect and refresh the scalp with Nioxin’s 3-part System 6 Scalp & Hair Treatment for Chemically Treated Hair with Progressed Thinning. This leave-on hair and scalp treatment is particularly formulated for chemically treated hair with progressed thinning. Thanks to Scalp Access Delivery System 2.0 technology, Nioxin’s diameter-increasing treatment helps prevent hair loss due to breakage, providing a refreshed scalp environment. Nioxin’s Scalp & Hair Treatment is the final step of a 3-part System, designed to strengthen the hair and amplify hair structure.