Tinea versicolor, also known as pityriasis versicolor, is a fungal infection affecting the skin. It is caused by a yeast that occurs naturally on the skin, but which grows out of control, resulting in a rash. It is particularly common in tropical, hot or humid climates.

One of the most common symptoms of tinea versicolor is the appearance of patches of discolored skin, usually in back, neck, upper arms and chest, which appear lighter or darker than normal. Other symptoms include mild itching and scaling of the skin. 

While the fungus at the root of tinea versicolor is naturally occuring, it may grow out of control in hot and humid weather, or when patients have oily skin; are going through hormonal changes; or have a weakened immune system. 

Treatment of tinea versicolor typically involves anti-fungal medications, which are usually applied topically. Drug classes commonly used to treat tinea versicolor are topical dermatological antifungals, azole antifungals, and topical dermatological antifungals.