Patches of melasma are darker than other areas of skin because they have more pigment. The cells that produce pigment in the skin are called melanocytes. Ultraviolet radiation, or UV rays, from the sun stimulate melanocytes to produce pigment. After your skin is exposed to the sun, melanocyte production increases, which in some cases can result in melasma. After the melasma clears up, even a small dose of sunlight can cause it to return.
Even though science continues to provide some answers about the condition, researchers don't know for sure why melasma affects some people and not others. What they do know is that certain factors increase your chances of getting it, including the following ones:
- A family history of melasma
- Darker skin -- People who have more active melanocytes have more pigment in their skin, making them more likely to have patches of melasma.
- Tropical climates -- Those who live in these areas are frequently exposed to the sun.
- Products that irritate the skin -- These may cause melanocytes to produce more pigment, and this can worsen the condition of melasma.
- Anti-seizure medication
- Phototoxic drugs -- These make the skin more sensitive to light damage [source: Merck].
Studies also associate the condition with a rise in the levels of the hormones estrogen and progesterone, which is probably why melasma is more common in pregnant women, women who take birth control pills and women who have hormone replacement therapy.
But melasma doesn't affect everyone in the same way. To find out how to treat different cases of the skin condition, move ahead to the next page.