What Causes Toenail Fungus?

Fungal infections cause about 50% of nail abnormalities. Nail fungus can make fingernails and toenails discolored, thick, and crumbly. It can develop on any nail, but it’s particularly common on toenails.

Toenail fungus can be unsightly and embarrassing, but Mountain View Foot & Ankle Institute can help. David B. Glover, DPM, FACFAS, and our team regularly treat fungus with laser technology, which can eliminate infections and restore nail health.

How fungal infections develop

Fungi exist naturally in the environment. People have yeasts, molds, and other fungi organisms on their skin, but most of the time, they don’t develop into an infection.

When a fungus enters the skin through a small cut or a crack in your nail, it can trigger overgrowth and infection. Fungi thrive in warm, moist environments, and the conditions of a nail bed can encourage excessive growth.

Once under your nail, the fungus can multiply and spread, damaging your toenail. Fungal overgrowth usually begins as a small white or yellow spot under your nail. The nail may get discolored, thicker, and more brittle over time.

Toenail fungus can develop as a side effect of athlete’s foot, which is a type of foot fungus that causes an itchy rash between your toes. It can also spread from one toe to surrounding nails.

Risk factors for fungal infections

Your feet are at the greatest risk for developing a toenail fungal infection when they’re in warm, moist environments. Having sweaty feet or wearing tight-fitting, closed toed shoes most of the time can make toenail fungus more common.

Going barefoot in public spaces, such as swimming pools and gym locker rooms, can increase your chances of developing toenail fungus. Nail salons can spread fungal infections if tools aren’t properly sanitized between customers.

While anyone can develop a toenail fungal infection, some people may be at a greater risk of developing this foot problem. You could be more likely to suffer from toenail fungus if you:

People with a history of injuring their toenails or other foot problems are more likely to develop fungal infections, because the nails may be more brittle and prone to cracking.

Preventing and treating fungal infections


Practicing healthy foot hygiene is the best way to prevent fungal infections. Keep your feet clean and dry, and regularly trim your toenails. Wear breathable socks and shoes, and consider wearing shoes in public spaces where fungus can spread easily.


Laser treatment is a safe and effective option to destroy the infection in an infected nail. Treatments are painless and performed on an out-patient basis. During treatment, a gentle laser kills the organisms embedded in the nail and leaves the surrounding tissues unharmed. A few quick sessions should clear up the infection and give your nail the opportunity to heal. 

If you have problems with toenail fungus, we can help. To learn more, book an appointment online or over the phone with Mountain View Foot & Ankle Institute today.

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