Greasy hair is caused by over-active sebum production, which irritates and destabilizes the scalp. Hair quickly becomes limp, dull and lifeless. The treatment shampoo Vichy Dercos Oil Control Shampoo thoroughly cleanses the scalp and delays oiliness. It contains an exclusive anti-sebum complex which combines 4 carefully balanced and selected surfactants to help limit the spread of sebum along the capillary fibers and preserve the scalp's natural balance.