Common Symptoms and Causes of Toenail Fungus

May 7th 2016

Causes of Nail Fungus: Dermatophytes

Dermatophytes are fungi that grow on the skin, nails and hair. The most well-known dermatophyte is Trichophyton rubrum, the fungus responsible for athlete's foot. This fungus can also affect the toenails; dermatophytes are the most common cause of toenail fungus problems. Trichophyton rubrum and other dermatophytes can be caught through simple contact, and people often get them by touching infected clothing, toenail clippers or locker room floors.

Causes of Nail Fungus: Molds and Yeast

The body naturally carries yeast, but when the yeast experience an overgrowth due to the use of antibiotics, immune system problems or use of birth control pills, an infection can occur. Molds can also cause a toenail fungus problem, although those types of infections aren't normally contagious between people.

Symptoms of Nail Fungus

The first visible sign of toenail fungus is often a white or yellow spot on the nail. Toenails with nail fungus can become thickened and distorted in shape. They may become brittle or ragged, and sometimes they begin to crumble at the edges. As the fungus spreads, the nails may become dark. Sometimes bits of the nail flake off, or the surface of the nail may become pitted. The nail can also begin to emit a foul odor. In extreme cases, the entire nail may come off. The presence of nail fungus is confirmed by examining a portion of the nail or scrapings from it under a microscope.


Nail fungus, also known as onychomycosis, occurs when a fungus infects a fingernail or toenail and causes it to become discolored and thick. Some people are particularly susceptible to nail fungi and tend to develop onychomycosis when they come in contact with the infectious agent. Older women are more likely to develop toenail fungus, as well as diabetics, people who have recently sustained a nail injury and people who wear artificial nails. There are several types and causes of nail fungus, all of which create similar symptoms; other nail infections, including eczema and psoriasis, can also cause similar symptoms.

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