Uneven skin tone can occur for many reasons. The most well known reasons are (1) uneven build up of Melanin or (2) lack of sebum production.


Melanin is the substance that results in the pigmentation (coloration) of skin cells. Some areas of the skin simply have less melanin than other areas. As the cells containing more melanin come in contact with prolonged periods of sunlight, they become darker. Other areas with less melanin or that have less exposure to the sun, remain lighter. Patches with the most melanin, if not exfoliated regularly, can darken considerably when compared to areas with less melanin. This gives the skin an appearance of an uneven skin tone. Exfoliating the surface cells -- the ones with the most contact with sunlight (the darkest) -- will give you an even skin tone.


Oily skin has a tendency to produce very little sebum -- the cellular 'glue' that binds the skin together. Therefore, dead skin cells tend to solidify and 'stick' to the skin's surface for longer than normal. The result is uneven patches of skin tone. Many people resort to manual exfoliating and scrubs. This often is too harsh for dry or sensitive skin. Sometimes when exfoliation is not done, the patches stick for so long that the surface skin hardens and cracks. Over time, these cracks go deeper and deeper into the dermis, causing permanent scarring. This is a vicious cycle that can be avoided with proper skin care.
Regular exfoliation and proper daily cleansing can keep your skin looking healthy and help prevent an uneven skin tone.