How does vitamin D3 help treat psoriasis?

Prescription forms of vitamin D3 can be used in small amounts when psoriasis affects less than 20% of the body's surface. These drugs, such as calcipotriene (Dovonex) and calcitriol (Vectical), slow the rate of skin-cell growth and are very different from the regular vitamin D supplements you can buy in any drugstore.

Today, combinations of vitamin D3 drugs and corticosteroids are widely considered the most effective treatments for mild to moderate psoriasis.