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By: Zoe Diana Draelos, MD
Posted: January 7, 2009, from the January 2009 issue of Skin Inc. magazine.
This article originally appeared in the October 2008 issue of Cosmetics & Toiletries magazine. Reprinted with permission. All rights reserved.
Irregular pigmentation of the face is one of the most common signs of photoaging. Pigmentation occurs because of 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 between the ages of 25–30 years, 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, and is most commonly seen during pregnancy and menopause, as well as with the use of oral contraceptives. Lastly, increased facial pigmentation can present as an overall skin darkening in people age 50 years or older due to a combination of melanin pigment and fragmented elastin fibers.
Other factors also influence facial pigmentation, such as gender. Because men do not experience the same hormonal issues, increased facial pigmentation from melasma is uncommon. The coarse skin texture of the male face from hair growth camouflages the fine freckling that is evident on the female face. Finally, the male face is more resistant to UVA damage due to its increased thickness from the terminal beard hairs that are present. 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.
There are also racially based differences in skin pigmentation problems. Individuals who have darker skin are more prone to skin darkening. This is due to the enhanced ability of darker skin to produce melanin. Pigment may be produced in response to sun exposure, skin disease and skin trauma. It is distinctly more difficult to lighten skin in individuals with darker complexions. Although pigmentation problems may be more visible in those with lighter skin, over-the-counter (OTC) skin-lightening preparations are more successful with this population.
Methods of skin-lightening
There is no doubt that the best method of skin lightening is to avoid sun damage. In fact, all OTC skin-lightening treatments should include a sunscreen. Sunlight contains visible light, and invisible UVB and UVA radiation. Visible light and UVB radiation do not tan the skin. Skin tanning in people of all skin colors is due to UVA radiation. Most sunscreens focus on preventing sunburn, which is due to UVB radiation. They do not prevent tanning, since skin isn’t protected from UVA radiation. Thus, sunscreens selected for skin-lightening purposes should contain UVA photoprotectants such as avobenzone, oxybenzone, zinc oxide and/or titanium dioxide.