This treatment combines a plant-derived substance called psoralen with light therapy (photochemotherapy) to return color to the light patches. After you take psoralen by mouth or apply it to the affected skin, you're exposed to ultraviolet A (UVA), UVB light or excimer light. These approaches tend to have better results than just medication or just light. You may need to repeat treatments up to three times a week for six to 12 months.
This therapy may be an option if your vitiligo is widespread and other treatments haven't worked. A depigmenting agent is applied to unaffected areas of skin. This gradually lightens it so that it blends with the discolored areas. The therapy is done once or twice a day for nine months or longer. Side effects can include redness, swelling, itching and dry skin. Depigmentation is permanent, and you'll always be extremely sensitive to sunlight.