Vitiligo is a long-term skin condition characterized by patches of the skin losing their pigment. The patches of skin affected become white and usually have sharp margins. The hair from the skin may also become white. The inside of the mouth and nose may also be involved. Typically both sides of the body are affected. Often the patches begin on areas of skin that are exposed to the sun. It is more noticeable in people with dark skin. Vitiligo may result in psychological stress and those affected may be stigmatized.The exact cause of vitiligo is unknown. It is believed to be due to genetic susceptibility that is triggered by an environmental factor such that an autoimmune disease occurs. This results in the destruction of skin pigment cells. Risk factors include a family history of the condition or other autoimmune diseases, such as hyperthyroidism, alopecia areata, and pernicious anemia. It is not contagious. Vitiligo is classified into two main types: segmental and non-segmental. Most cases are non-segmental, meaning they affect both sides; and in these cases, the affected area of the skin typically expands with time. About 10% of cases are segmental, meaning they mostly involve one side of the body; and in these cases, the affected area of the skin typically does not expand with time. Diagnosis can be confirmed by tissue biopsy.There is no known cure for vitiligo. For those with light skin, sunscreen and makeup are all that is typically recommended. Other treatment options may include steroid creams or phototherapy to darken the light patches. Alternatively, efforts to lighten the unaffected skin, such as with hydroquinone, may be tried. Several surgical options are available for those who do not improve with other measures. A combination of treatments generally has better outcomes. Counselling to provide emotional support may be useful.Globally about 1% of people are affected by vitiligo. In some populations it affects as many as 2–3%. Males and females are equally affected. About half show the disorder before age 20 and most develop it before age 40. Vitiligo has been described since ancient history.