High Quality Content by WIKIPEDIA articles! Betamethasone is a potent glucocorticoid steroid with anti-inflammatory and immunosuppressive properties. Unlike other drugs with these effects, betamethasone does not cause water retention. It is applied as a topical cream, ointment, foam, lotion or gel to treat itching. Betamethasone sodium phosphate is sometimes prescribed as an intramuscular injection (I.M) for itching from various ailments including allergic reactions to poison ivy and similar plants.