Genetics play a role in the development of melasma. People with darker skin, such as those of Asian, Indian, African and Middle-Eastern descent, are more likely to get melasma. Melasma occurs when the pigment-producing cells (melanocytes) produce too much pigment. People with a blood relative with melasma are much more likely to develop melasma.
Ultraviolet (UV) light from the sun stimulates pigment-producing melanocytes to produce more pigment. In fact, just a small amount of sun exposure can make melasma recur after it has faded. This is the reason why melasma is usually worse in summer.
Hormones are thought to be a significant driving force in the development of melasma. Pregnancy, oral contraceptive pills and hormone replacement treatment are all possible triggers for melasma.
Skin irritation from creams, lasers, IPL, waxing and other means can aggravate and worsen existing melasma. For this reason, it is important to ensure that all skin-care products and treatments are particularly gentle and non-irritating.