Nail Infection, Fungal (Onychomycosis)

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Images of Onychomycosis


Onychomycosis is a fungal infection of the fingernails or toenails. Fungal infections are caused by different kinds of yeast and fungi that are different than bacteria. The infection can affect any part of the nail: the nail itself, underneath the nail, or the cuticle. Unlike a bacterial infection, fungal nail infections are usually not painful but they do disrupt the normal growth of the nail and change the appearance of the nail, often making the nail look white or crumbly. Fungal nail infections may be difficult to treat, and topical antifungal drugs will usually not cure the nail condition; you will need to speak to your doctor about effective treatment. Fungal nail infections are contagious, particularly to people with problems with their immune systems, so it is important to wash your hands thoroughly and carefully and to not share towels or other intimate objects with others.

Who's at risk?

Fungal nail infection may occur at any age but are relatively rare in children and more common in teens and adults. Diabetics and those with HIV/AIDS or other immunosuppressive conditions may be more likely than others to develop a fungal nail infection.

Signs and Symptoms

  • In general, the toenails are most commonly affected by a fungal nail infection. If the fingernails are affected, the toenails are usually affected as well. Nails often become thicker and lift from the nail bed (onycholysis) starting at the growing portion of the nail. You might then see debris under the nails and discoloration of the affected area.
  • In some forms of fungal nail infection, you might see black or white, powdery discoloration on the surface of the nail plate.
  • Also in some forms of fungal nail infection, you might see these abnormal changes farther up the finger (proximally), where the nail originates.
  • Fungal nail infection may occur in people with athlete's foot (tinea pedis) and/or oozing infection (paronychia), caused by inflammation and infection with yeast and/or bacteria in the region where the skin of the finger meets the origin of the nail.
  • In fungal nail infection, one, a few, or all nails may be affected.

Self-Care Guidelines

  • None necessary except good hygiene and regular washing of the hands and feet.

When to Seek Medical Care

Fungal nail infection does not always require treatment, but see your doctor for any nail disorder. Diabetic patients with foot problems should be evaluated because of the possible risk for developing foot ulcers. Your doctor may perform testing, such as scraping a nail to examine for fungi or clipping a nail to look for bacterial or fungal growth (culture) or to obtain a special stain to look for fungi under a microscope.

Treatments Your Physician May Prescribe

  • Topical therapy with ciclopirox nail lacquer, which requires daily application for 9–12 months.
  • Oral antifungal treatments offer the best chance for curing fungal nail infection. The most commonly used agents are terbinafine, itraconazole, and fluconazole. The medications may cause liver problems or may affect blood cell counts. Blood tests are usually performed before starting therapy and during therapy to look for possible side effects.
  • In stubborn (refractory) fungal nail infection, surgical removal of part of the nail or the entire nail, removing the nail by applying a chemical, or thinning the nail by applying 40% urea ointment may be used, in addition topical or oral antifungal agents.

Trusted Links

Clinical Information and Differential Diagnosis of Onychomycosis


Bolognia, Jean L., ed. Dermatology, pp.1062, 1072. New York: Mosby, 2003.