Vitiligo is a disease that causes the loss of skin color in blotches. The extent and rate of color loss from vitiligo is unpredictable. It can affect the skin on any part of the body. It may also affect hair and the inside of the mouth. Normally, the color of hair and skin is determined by melanin. Vitiligo occurs when the cells that produce melanin die or stop functioning. Vitiligo affects people of all skin types, but it may be more noticeable in people with darker skin.