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What is Toenail Fungus?

Over 46,000,000 Americans suffer from Nail Fungus ( Onychomycosis ) and 4,000,000 new cases are diagnosed each year.

Dr. Kline & Green Team
25 July 2019
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Nail fungus (scientific name onychomycosis [on-ih-koh-my-KOH-sis]), is a common condition that usually first appears as a discoloration, such as a white or yellow spot under the tip of the fingernail or toenail. As the fungus deepens, it may cause the nail to discolor, thicken, and crumble at the edge. An infection may spread to many nails, and often, it may appear concurrently with a skin fungus such as athlete’s foot (tinea pedis).

Fungal infection can vary in degree, warranting different levels and types of treatment. Cases which cause neither pain nor discomfort may require no special treatment at all. Those, by contrast, producing symptoms such as pain or a thickened nail may require specific types of self-care and or medication.

Even once successfully eradicated, however, fungal nail infections are likely to recur. Nevertheless, definite preventive measures can reduce the chance of re-infection.

Causes of Toenail Fungus

Fungal nail infections occur when various fungal organisms (fungi) found naturally in, on, or under the nail overpopulate. The fungi that most commonly produce nail infection are called dermatophyte. Other fungi, however, such as yeast and molds, can likewise cause nail infection.

A variety of factors can contribute to the overgrowth of these fungi, which are already present in your body. Because fungi thrive in warm, moist environments, overpopulation most often occurs in areas of the body that are regularly covered and warm. For this reason, nail fungus is a higher risk factor more commonly affects toenails, for example, than fingernails.

The same fungi that cause nail infection can also cause jock itch, athlete’s foot, and ringworm. One type of infection, therefore, can lead to another. Athlete’s foot (foot fungus), for example, can spread to the nails, causing toenail infection. Fungal infections can also be communicated from one person to another.

Fungal nail infection can develop in people at any age, but it tends to appear more frequently among adults over the age of 65. This trend is likely due in part to the drier, thicker, and brittler condition of aging nails, which, if cracked or chipped, may allow fungi to enter.

Other factors may also contribute to higher rates of infection and more severe cases among older adults, including reduced blood circulation to the feet and a weakened immune system.

Certain conditions that increase the likelihood of developing a fungal nail infection, therefore, include the following:

  • age, particularly if over 65
  • if you have diabetes
  • a disease that causes poor circulation
  • a nail injury
  • a skin injury around the nail, or a skin condition such as psoriasis
  • wet fingers or toes are in a damp environment for a long time
  • a weakened immune system
  • the occurrence of nail fungus among family members or previous fungal infections


Distinct behaviors that increase the risk of a nail infection include:

  • wearing artificial nails
  • walking barefoot in damp communal areas, such as gyms and shower rooms
  • swimming in a public swimming pool
  • wearing closed-toe shoes, such as tennis shoes or boots
  • frequenting a nail salon that fails to sanitize emery boards and nail clippers regularly and thoroughly

Simple lifestyle practices can help prevent fungal nail infection. The first and most important preventive measure is to keep your nails trimmed and clean.

  1. That’s awesome that there are many ways to treat fungal infections. My sister has been complaining about her feet itching a lot. We’ll have to look into nail fungus treatment.

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