Everyone has yeast within the skin on their face, neck, chest and back. In the summer, sweating can facilitate overgrowths of this particular yeast, causing a rash to occur.
Spot it: This appears as brown or white patches that grow slowly, usually on the chest or back, and prevent skin from tanning or burning after sun exposure. Mild itching may also occur.
Treat it: Stay out of the sun until patches clear up on their own, which could take several days or weeks, or risk uneven skin tones.
Prevent it: Keep your skin dry and clean, and avoid heavy lotions. If you're prone to tinea versicolor, use an antifungal shampoo or cream to prevent recurrences.