Selsun 2.5% Extra Strength Selenium Sulfide Lotion - Medicated dandruff control that works hard on dandruff. Selsun Blue shampoo is specifically formulated to control scaling, flaking and itching scalp associated with dandruff and seborrheic dermatitis. Proven effective to control and prevent flakes and is available in different forms. Selsun Blue powers away dandruff and leaves hair shiny and healthy so you can look your best! Always read and follow the label.