In most cases, the first treatment used will be a topical treatment, such as vitamin D analogues or topical corticosteroids. Topical treatments are creams and ointments applied to the skin. If these are not effective, or your condition is more severe, a treatment called phototherapy may be used. Phototherapy involves exposing your skin to certain types of ultraviolet light. In severe cases, where the above treatments are ineffective, systemic treatments may be used. These are oral or injected medicines that work throughout the whole body.