Toenail Fungus Facts and Treatment Options

Also known as onychomycosis, toenail fungus is a common problem and one of the most frequently treated foot conditions. It is a slow-growing infection caused by dermatophytes, which are fungi that infect skin, hair, and nails. Other fungi such as yeast and molds can also cause toenail fungus.

Signs of Toenail Fungus

Fungal infections usually occur underneath the nail and begin at the end of the nail (where it gets trimmed).

Less often, an infection can appear as a white, powdery discoloration on top of the nail. The most common changes that occur with toenail fungal infections include:

  • Discoloration beneath the nail, usually brown, white, or yellow​
  • Thickening of the nail​
  • An increase in white debris beneath the nail which is keratin, a protein that gives form to skin and nails​
  • Infected part of nail may become loose or separate from the nail bed​
  • Nail appears to "crumble" or breakdown

Who Gets Toenail Fungus?

Toenail fungus can affect anyone but becomes more prevalent with aging. Individuals with certain diseases -- such as diabetes, diseases that affect limb circulation -- are more susceptible to fungal nail infections, along with people who have suppressed immune systems.

Other risk factors include:

  • Hyperhidrosis, or a tendency toward sweaty feet
  • Frequent fungal skin infections
  • Trauma to the nail
  • Shoe wear--which provides a moist, dark, and warm environment for fungi to thrive

    How Toenail Fungus Is Treated

    Nail fungus is usually diagnosed by its appearance and symptoms that it causes. However, nail thickening and discoloration can be signs of other nail conditions. If there is uncertainty, laboratory tests performed on a sample of the nail may be used to make a definitive diagnosis.

    Because the fungi colonize the nail and skin beneath it, toenail fungus can be difficult to treat. Oral antifungal medicines have been the most effective means of treating toenail fungus but are not always an option for many people due to potential side effects and cost. There are a number of over-the-counter topical medications for toenail fungus. Because the fungus resides deep in the nail and underneath it, these medications have limited success in treating toenail fungus, especially if has spread significantly throughout the nail.

    Treatment at a podiatrist's office will likely involve debridement, or trimming down and removing debris and the dying nail. This will help decrease the thickness of the nail and relieve discomfort that may be occurring with shoe wear. Debridement may also increase the effectiveness of topical treatments. Oral antifungal medications and/or prescription strength topical treatments may also be prescribed. Other new fungal nail treatments are emerging, including laser treatment which recently received FDA approval.

    Toenail fungus does tend to be a recurring problem, even after successful treatment. For this reason it is recommended to take preventative measures such as using antifungal shoe sprays and powders to keep feet dry and decrease the chance of skin and nail fungal infection.

    Topical nail products such as nail polishes or lacquers with antifungal ingredients may also help decrease the recurrence of infection. It's also helpful to seek treatment at the first signs of nail changes, such as discoloration or thickening.


    Mozena, DPM, John D. and Mitnick, DPM, Joshua P. "Emerging Concepts In Treating Onychomycosis". Podiatry Today. Oct. 2009; 22(10):46-51.

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