​Ultraviolet (UV) light speeds up the production of melanin, a natural pigment to give the skin, eyes, and hair their colours. When melanin is produced in high concentrations, the affected area appears darker. Besides sun damage, other commonly known causes of brown spots are aging, hormonal changes, wound healing, inflammation, etc.

Melasma is like other brown spots; the body produces more than usual melanin causing dark brown and discoloured spots on the skin.​ In this case, hormonal change is considered the reason for the irregular production of melanin. Therefore, melasma is also called the “mask of pregnancy” when it happens to pregnant women. Other than pregnancy, birth control pills or hormone therapy can also trigger and develop melasma.

Most brown spots are harmless and can be treated with cosmetic laser or skincare products targeting pigmentation.