NIOXIN Scalp Treatment- System 4 (100ml) is a daily leave-in scalp treatment with SPF 15 sunscreen that protects scalp skin from harmful UVA and UVB rays - delivering essential botanicals, nutrients, antioxidants, vitamins and cytokines onto the scalp skin and hair to help safeguard against environmental residue and DHT build-up on the scalp. NIOXIN Scalp Treatment- System 4 (100ml) may cause temporary redness after application.