Athlete’s foot—the most prevalent foot fungus—thrives in warm, sweaty places like the insides of your athletic shoes, which is how it got its name. However, foot fungus can develop in multiple environments, natural and man-made, as long as there is lots of moisture where fungi can grow. These include shared areas at gyms or pools, soil and grass, or even shared items such as shoes, socks, or towels from household members who are infected.
Infected nails are usually thicker than normal and could be warped or oddly shaped. They can break easily. Nails with fungus might look yellow. Sometimes a white dot shows up on the nail and then gets bigger. When fungus builds up under your nail, it can loosen and even separate the nail from the bed. The fungus can also spread to the skin around your nail.