Betamethasone + Salicylic Acid is a combination of two medicines: Betamethasone and Salicylic Acid which treat eczema and psoriasis. Betamethasone is a steroid which blocks the production of certain chemical messengers (prostaglandins) that make the skin red, swollen and itchy. Salicylic Acid is a keratolytic medicine which breaks down keratin clumps, removes dead skin cells and softens the skin. It also enhances the absorption of Betamethasone into the skin.