Toenail fungus also known as onychomycosis is a fairly common condition that disfigures and can destroy the nail. This condition is caused by any one of many types of fungi (similar to the organisms that cause mold in your bathroom) that grow in the moist warm environment in your shoes. These fungi generally belong to a group of fungi called dermatophytes. As they grow they invade and feed on the protein (keratin) that makes up the hard surface of the toenails. It is rare in children but the incidence increases as you age, with an estimated 48% of people in the United States having at least one toe affected by the time they are 70 years of age. Wearing tight-fitting shoes and layers of polish in the nails increases the risk of developing this. It can also be spread person to person in public areas such as locker rooms and showers. Having a chronic condition such as diabetes that affects your circulation or HIV also increases your risk. The big toe and the little toe are the nails that are most likely to be affected. How to Avoid Fungus Spreading on Toenails. Toenail fungus has become a too common, embarrassing problem for people. Toenail fungus causes thick, brittle, painful nails that sometimes fall off, making it difficult to shop for shoes or go out, especially in the summer. While it takes several months to heal the fungus, there are some steps you can take so it does not spread to more of your toenails. Clean your feet and toes thoroughly and then dry them carefully, making sure to get the excess moisture. If needed, use your hair dryer on a low setting. Remember: Fungus thrives on moisture, so the feet must be perfectly dry. Apply an anti-fungal powder to your feet to prevent further breakouts. Step 2 Keep your feet well groomed and filed to prevent ingrown or torn toenails. If your toenails are injured, fungus has a better chance of reoccurring. Cut the toe nails straight and short, beneath the tips of your toes. Use different clippers if one of your nails is infected with fungus, so as not to spread it. Remember to disinfect your tools to also prevent spreading fungus. Step 3 Wear flip-flops or other footwear if you are using a community pool or shower area, because many people use those areas, and fungus loves those moisture-breeding areas. Spray and clean your own shower at least weekly to disinfect for any fungus living in your bathroom. Step 4 Wear breathable, cotton socks, and change them daily to avoid severe perspiration. Consider having two comfortable pairs of shoes that you can change up, and wear on alternating days to avoid sweating in either pair.