Melasma is caused by hormonal changes, sun and genetic predisposition. Hormone changes include external hormones such as the oral contraceptive pill or internal hormones changes due to pregnancy, polycystic ovaries (PCOS) and the menopause.
It is more common in women aged 20 to 50 years but can also occasionally affect men. Women with olive or darker skin tones have a higher incidence. It is more pronounced in the summer.