Nail fungus is a common condition that can cause your nails to become discolored, thick, and brittle. Nail fungus is usually not painful, but it can be unsightly. Nail fungus is caused by a group of fungi called dermatophytes. Dermatophytes are microscopic organisms that thrive in warm, moist environments. Nail fungus is usually spread through direct contact with an infected person or object. Nail salons and public showers are common sources of nail fungus infections. Nail fungus can also be spread from one person to another through contact with contaminated towels or other personal items. Nail fungus can spread to other parts of the body, but this is uncommon. Nail fungus is more likely to spread to the skin around the nail or to the surrounding nails. If you have nail fungus, it is important to practice good hygiene to prevent the spread of the infection. You should avoid sharing personal items with others and keep your nails clean and trim. If you have nail fungus, see your doctor for treatment. Nail fungus can be difficult to treat, but there are many effective treatments available.