The condition causes patches of dark discoloration to occur on your skin. These patches are darker than your typical skin color. While the majority of cases occur on the face, other areas of your body that are often exposed to sun can also develop melasma. When it occurs on the face, it is typically symmetrical, with marks on both sides of the face matching
Estrogen and progesterone have been associated with the condition; birth control pills, pregnancy, and hormone therapy can all trigger melasma. Sun exposure is also a cause of melasma because the ultraviolet rays affect the cells that control pigment. Darker-skinned individuals are more likely to experience melasma than fair-skinned individuals.