Two prescription medications—Vectical and Dovonex, which are applied to the skin—include vitamin D as their main active ingredient. Edee Scott, 72, of Corona, Calif., says vitamin D medication has helped calm her psoriasis, which is most severe on the palms of her hands and feet. She's had psoriasis since age 14, but it's only in the past 15 years that her psoriasis has taken on a life of its own, she says.