1 Betamethasone dipropionate is a potent corticosteroid which is applied directly to the affected area of the skin or scalp. 2  In general this drug is used to treat severe inflammatory skin conditions which have not responded to less potent corticosteroids. Betamethasone dipropionate is a potent corticosteroid which is applied directly to the affected area of the skin or scalp. 2  In general this drug is used to treat severe inflammatory skin conditions which have not responded to less potent corticosteroids.