The condition is characterized by skin discoloration typically located on areas of the body more exposed to the sun, such as the cheeks, nose, forehead and chin and to a lesser extent, the neck and arms.
The exact cause is not known, but several factors contribute. These include pregnancy, hormonal drugs such as the contraceptive pill, and very occasionally medical conditions affecting hormone levels. Some cosmetics, especially those containing perfume, can bring on melasma. Sunshine and the use of sun-beds usually worsen any tendency to melasma.