Nail fungal infections are caused by a group of fungi called dermatophytes. Pathogens that cause nail fungus infections usually enter the skin through tiny cuts or small separations between the nail and nail bed. The fungi grow when the nail provides a suitably warm and moist environment. Nails that are infected with fungus typically are thickened, brittle, crumbly, ragged, distorted, dull, and darker or yellowish in color. A patient may also experience onycholysis, where infected nails separate from the nail bed. Sometimes, nail fungal infections result in pain in the toes or fingertips, and they may even emit a slight foul odor.
