Toenail fungus causes

Causes of Toenail Fungus

Although some cases of onychomycosis, or toenail fungus, may be present for years without any visible symptoms, eventually the infected toenail will become thick and difficult to cut, with layers of nail and skin debris beneath it. Others may turn a dark yellow or green, become dull instead of shiny, develop white spots that spread to cover the whole nail, or even change shape. 


All of these infections are caused by microscopic organisms of varying types. Although they’re usually grouped together as toenail “fungal” infections, the organism could be a fungus, mold, or yeast. The most common culprits are dermatophyte fungi, which are also responsible for athlete’s foot, an infection of the skin between the toes.

Medical Conditions 

Candida is another organism sometimes responsible for infection, although much less commonly than dermatophytes. It usually develops in people with a compromised immune system, especially those with HIV or diabetes. The feet receive less blood flow than much of the body, which means the immune system catches infection there much more slowly, and it’s more difficult for it to fight them. People with underlying disorders should be especially cautious in contagious areas. 


Environment plays a large role in developing toenail fungus. These organisms thrive in warm, moist areas, with pools and showers being particularly dangerous. Walking barefoot in these places almost guarantees an infection. They enter through cracks in the nails, cuts in the foot that are too small for humans to see, and places where the nail has separated from the skin. You take them from there to your shoes, which are also warm and moist.

Just sharing a shower with or borrowing a pair of sneakers from someone who has a fungus can spread it about. Take special care to be exceptionally hygienic in these areas. Use anti-fungal powders and creams on your footwear. Opt for socks that are “moisture wicking,” like wool, and wear flip flops in the locker room. Remember that just because you can’t see the organisms doesn’t mean they aren’t there.

Last Updated: March 17, 2016