Selsun shampoo is a quick, simple and highly effective medical treatment for dandruff. Selsun shampoo contains 2.5% w/v selenium sulphide, which works throughout the day to clear up dandruff and seborrhoeic dermatitis (a greasy, crusting itching scalp caused by excess oil). It works against dandruff in 2 ways; by reducing the greasiness of the scalp and by slowing down the growth of the layer of skin cells on the scalp that cause dandruff. Directions Not recommended for children under 5 years. Children aged 5-14, adults and the elderly- thoroughly wet hair and apply liberally massaging into the scalp to form a lather. Rinse after 3 minutes. Use twice a week for the first two weeks and then for once a week for the next two weeks to control the condition.  Thereafter use only as aften as necessary to control the condition. Not to be used in pregnancy or in breast feeding mothers.