Onychomycosis: fungal nail infection


Onychomycosis (tinea unguium) is a fungal infection of the nail bed, matrix or plate. Toenails are affected more often than fingernails. Onychomycosis accounts for one third of integumentary fungal infections and one half of all nail disease.

According to the November 2000 issue of the Journal of the American Academy of Dermatology, onychomycosis is also the most common nail disorder among people withdiabetes, representing about 30 percent of cutaneous fungal infections.

In the most common form of fungal nail infections, fungus grows under the growing portion of the nail and spreads up the finger (proximally) along the nail bed and the grooves on the sides of the nails.


The primary fungi that cause onychomycosis are trichophyton rubrum and trichophyton mentagrophytes. They are dermatophytes (fungi that infect hair,skin, and nails) and feed on keratinized (nail) tissue. The infections they cause are normally confined to the nails, but occasionally spread to the surrounding skin.

Another type of onychomycosis is caused by yeast (candida albicans or candida parapsilosis). These infections are less common and produce similar symptoms.

Paronychia infections are caused by bacteria such as staphylococcus, streptococcus, and pseudomonas. In most cases, paronychia infections can be differentiated from onychomycosis by the inflammation they cause to the skin adjacent to the nail


  • In general, toenails are most commonly affected with 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.
  • 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 infecion, one, a few, or all nails may be affected.

Treatment Options for Onychomycosis

Onychomycosis is difficult to treat because nails grow slowly and receive very little blood supply. However, there have been recent advances in treatment options, including oral and topical medications.

Onychomycosis can be a serious ailment, but some simple and effective treatments are available.

  • Having a healthcare professional regularly trim the nails and file down the nail plate with a surgical burr—a procedure called debridement—tends to reduce pain and fungal load, prevent ulceration and at least temporarily improve the nail’s appearance. This procedure can also be performed in conjunction with topical and oral antifungal therapies.
  • Topical antifungals have traditionally been unsuccessful in treating onychomycosis. However, using the antifungal lacquer ciclopirox for up to one year can often help diminish the infection.
  • The oral antifungal treatment Lamisil (terbinafine hydrochloride tablets) has a cure rate of about 70 percent, with few side effects and minimal drug interactions. With oral therapies, the patient’s liver function must be monitored for any rarely occurring hepatic complications.
  • If you do not want to try to cure the condition you can control onychomycosis and improve the appearance of the nails by brushing on FDA approved undecylenic acid.
  • Removal of the nail will not get rid of onychomycosis. When the new nail grows in, it almost always becomes re-infected.

Diabetic Complications

Patients with diabetes commonly develop onychomycosis because blood circulation is poor in the extremities, and the body’s ability to fight infections is compromised. Small cuts, infections, and foot injuries can have serious consequences for diabetics. Recent studies have shown a higher rate of amputation in diabetics with onychomycosis compared to those without the infection. It is important to inspect the feet closely each day and work with a physician on a program of thorough foot care.

Fungal nail infection does not always require treatment, but see your doctor for any nail disorder. Diabetics 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.

The first line of defense against onychomycosis is good hygiene. Preventing onychomycosis is the best option, but quick and effective treatment is available if all else fails.


The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

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