Nail Fungus Risk Factors & Causes

Nail fungus is more common among older adults for several reasons including diminished blood circulation, more years of exposure to fungi and because nails may grow more slowly and thicken with aging, making them more susceptible to infection. Nail fungus also tends to affect men more than women and those with a family history of this infection. Infection with nail fungus occurs more in toenails than in fingernails because toenails are often confined in a dark, warm, moist environment inside your shoes — where fungi can thrive.

Fungi are microscopic organisms that don't need sunlight to survive. Some fungi have beneficial uses, while others cause illness and infection. Nail fungal infections are typically caused by a fungus that belongs to a group of fungi called dermatophytes. But yeasts and molds also can be responsible for nail fungal infections. All of these microscopic organisms live in warm, moist environments, including swimming pools and showers. They can invade your skin through tiny invisible cuts or through a small separation between your nail and nail bed. They cause problems only if your nails are continually exposed to warmth and moisture — conditions perfect for the growth and spread of fungi.

These factors also can increase your risk of developing nail fungus: perspiring heavily, working in a humid or moist environment, wearing socks and shoes that hinder ventilation and don't absorb perspiration, walking barefoot in damp public places, such as swimming pools, gyms and shower rooms. A minor skin or nail injury, a damaged nail, diabetes or a weakened immune system can also make you more susceptible to fungal infections. Learn more about treatment options