Nail fungus affects toenails more often than fingernails ... A red area will appear that may turn purple over time and then brown or black. People may notice this after they stub their toes ...

In this instance, they "may look yellow, brown, black, or even green," Weiss says. These can pop up anywhere on the nail, either in spots or vertically along the nail. Like many fungal infections ...

How do dermatologists diagnose nail fungus? To find out if a patient has nail fungus, a dermatologist examines your nails and nearby skin. It’s important to check the skin because the fungus can ...