Betamethasone is a high potency topical prescription steroid used to treat skin irritation, skin rashes, and psoriasis. Topical corticosteroids are essential tools for treating inflammatory skin conditions such as seborrheic dermatitis, plaque psoriasis, atopic dermatitis (eczema), contact dermatitis, and Lichen planus. Topical betamethasone reduces local inflammation by blocking chemical reactions that cause inflammation, changing how immune cells work, and constricting blood vessels.