An infection of the toenail is called onychomycosis (on-i-ko-my-ko-sis). The nail may look brownish, yellowish or have little white patches. The nail may be flaky, brittle, ragged and chipped, and debris may collect under it. The toenail may get so thick that wearing shoes can cause pain. Infected nails may also separate from the nail bed, a condition called onycholysis.
Nail fungus is more common among the older population. Factors that can increase the risk of developing nail fungus include walking barefoot in a damp environment, such as around a swimming pool; circulation problems; diabetes; and a weakened immunity system.