Use of a cosmetic composition comprising an extract of Dianthus carthusianorumfor care of oily skin, is claimed. An independent claim is included for Dianthus carthusianorumextract, as agent regulating sebum production and/or as agent for regulating the proliferation of sebocytes for the prevention and/or treatment of oily skin. ACTIVITY : Dermatological. MECHANISM OF ACTION : 5alpha Reductase inhibitor.