Pregnancy mask, discoloration, brown patches, mustache—whatever you call it, melasma is a common skin condition that affects around six million women in the United States.

Melasma is a pigmentation disorder characterized by brown or grey-brown patches on the skin. You can develop melasma anywhere, but it most commonly appears on the forehead, around the mouth (especially upper lip), or along the outer perimeters of the face and cheeks.

Essentially, melasma is an overproduction of melanin. Melanocytes are cells that live in the dermis (the deepest layer of the skin) and produce melanin (pigment). Melanin is bundled up in melanosomes, which move up to the surface of the skin and disperse. This then shows up as color on the skin.

No one is quite sure what actually causes melasma, but there are a few well-known triggers. Hormones are the most common trigger, but other possibilities include UV exposure and skin irritation. Melasma doesn’t pose any medical risk, but once the melanin factory turns on, it can be hard to calm fussy pigment cells back down.

• Women: Women’s hormones stay quite active throughout adulthood whereas men’s hormones tend to calm down after adolescence. Since hormonal fluctuations are a common trigger for melasma, women are far more prone to it than men. In fact, 90 percent of melasma cases occur in women. 
• Those who are pregnant: Few hormonal fluctuations are as intense as pregnancy! In fact, melasma is often referred to as the “mask of pregnancy” because so many women start to experience it during this time. 
• Those on hormonal birth control: Since many hormonal birth control methods essentially mimic a state of pregnancy in the body, prolonged use can definitely trigger melasma. Learn more about how birth control affects the skin. 
• Those with deeper skin tones: As I mentioned, melasma stems from an overproduction of melanin. Those with deeper skin tones have more active melanocytes than those with lighter skin, so it’s easier for them to be over-stimulated. 
• Those genetically predisposed: If one of your immediate relatives has melasma, you’re more likely to develop it at some point.

• In a well-lit room, after cleansing your hands and face, gently stretch the area of the face that appears discolored.
• If the skin appears lighter when stretched than when at rest, the pigmentation is close to the surface and mostly superficial. This means it’s likely not melasma, rather one of the other three types of hyperpigmentation.
• If the skin appears darker when stretched than when at rest, the pigmentation lies in the deepest layers of the skin and will be more challenging to treat. If it is truly melasma, it will more than likely be in the deeper layers.