versicolor is caused by yeast called Malassezia furfur that lives in the skin of most adults. Factors that can cause the fungus to become more visible include high humidity and immune or hormone abnormalities.
condition are perfectly healthy. This fungus is part of the normal adult skin, this condition is not contagious. It often recurs after treatment, but usually not right away, so that treatment needs to be repeated only every year or two.
Over-the-counter (OTC) remedies include clotrimazole and miconazole. These should be applied twice a day for 10-14 days.
Another OTC option is selenium
sulfide shampoo 1% (Selsun Blue) or 1% ketoconazole shampoo. You can apply it overnight and wash it in the morning for a couple of weeks.
The hypo pigmented patches tends to linger even after successful treatment, especially if the spots are lighter than surrounding skin. It may take months for skin color to blend and look normal, but it always does. It is okay to expose the skin to sunlight.
Ref:http://www.medicinenet.com/tinea_versicolor/index.htm