First things first: Let's start with what hyperpigmentation actually is. According to Dr. Joshua Zeichner, the director of cosmetic and clinical research in the department of dermatology at Mount Sinai Hospital in New York, it's simply, "when you have extra pigment in the skin." The causes, however, are a bit more complicated.
The most common culprit? Dr. Zeichner says it's excessive exposure to UV light, which "causes your pigment producing cells to go into overdrive and leads to sunspots aka solar lentigines or liver spots." These spots tend to show up later in life (usually in the mid-30s and beyond) and are more prevalent on the face and hands.
"In some cases, hyperpigmentation may be due to hormonal fluctuations and is characterized by dark patches on the cheeks and temples or around the mouth," explains Dr. Zeichner. "It tends to get worse during pregnancy, which is how it was given the nickname 'the mask of pregnancy.' It can also by triggered by external hormones like oral contraceptive pills (which is something you may have noticed after switching to a new birth control) or exposure to excessive heat."
Whatever the cause, there are myriad options for treating and preventing hyperpigmentation altogether. The first place to start? Daily and diligent sunscreen application.