Irregular pigmentation of the face is one of the most common signs of photo-aging. Pigmentation is due to the uneven production of melanin, a brown pigment produced by melanocytes in the skin. Many different patterns can be seen on the faces of people of different ages. Small localized brown spots in the form of freckles across the cheeks, medically known as lentigenes, usually appear around the age of 25–30, depending on cumulative sun exposure. Pigmentation can also present in the form of melasma, a diffuse darkening of the skin over the sides of the forehead, lateral jawline and upper lip. This type of skin darkening is hormone dependent, most commonly seen during pregnancy, around menopause and with the use of oral contraceptives. Lastly, increased facial pigmentation can present as overall darkening in people after 50 years from a combination of melanin pigment and fragmented elastin fibers.
Other factors also influence facial pigmentation, such as gender. Since men do not experience the same hormonal issues as women, increased facial pigmentation from melasma is uncommon. While male testosterone may cause some skin issues, it is female estrogen that produces facial pigmentation. The coarse skin texture of the male face from hair growth camouflages fine freckling that is often seen on the female face. Finally, the male facial skin is more resistant to UVA damage due to its increased thickness from the terminal hairs present as a beard on the face. UVA radiation penetrates deeply within the skin, but not as readily into thicker male skin as it does into thinner female skin. Because UVA damage is the primary cause of pigmentary abnormalities, pigment lightening products are more commonly used by females than males.