If a fungus invades the toenail and/or the nail bed, the toenail becomes discolored, brittle, thickened, and eventually deformed if not treated. Commonly, the fungus is the same fungus responsible for athlete's foot. The infection starts at the top of the nail and works its way back, ultimately invading the nail bed. This distorts the growth of the nail. There is relatively no pain associated with fungal nails and often they go unnoticed. Sweaty feet are the main culprit. Treatment generally involves clipping away the diseased portion of the nail and applying an antifungal medication. Over-the-counter and prescription oral and topical medications can also provide sine relief but may not clear up the infection. Oftentimes trauma or pressure to the nail can cause the same appearance of that of a fungus-infected nail, especially of the great toe and baby toe, as these are more likely to receive pressure from shoe gear. Oftentimes a nail culture is necessary in order to definitively diagnose nail fungus.
Keep feet clean and dry. Change socks daily. Keep common shower areas clean and do not share shoes and socks.