Causes, incidence, and risk factors

The body normally hosts a variety of bacteria and fungi. Some of these are useful to the body. Others may multiply quickly and form infections. Fungi can live on the dead tissues of the hair, nails, and outer skin layers.

Fungal infections include mold-like fungi that cause:

• Athlete's foot

• Jock itch

• Ringworm on the skin of the body or head

Fungal nail infections are most often seen in adults. They often follow fungal infection of the feet. Toenails are affected more often than fingernails.

People who often go to public swimming pools, gyms, or shower rooms, and people who sweat a great deal, often have mold-like infections. The fungi that cause them thrive in warm, moist areas.

The following increase the risk of a fungal infection:

• Getting manicures and pedicures using utensils that have been used on other people

• Getting minor skin or nail injuries

• Having a nail deformity or nail disease

• Having moist skin for a long time

• Poorly functioning immune system

• Wearing closed-in footwear

Symptoms

• Nail changes on one or more nails (usually toenails):

  • Brittleness

  • Change in nail shape

  • Crumbling of the outside edges of the nail

  • Debris trapped under the nail

  • Loosening or lifting up of the nail

  • Loss of luster and shine

  • Thickening of the nail

  • White or yellow streaks on the side of the nail

Signs and tests

Your doctor will suspect a fungal infection based on the appearance of the nails.

The diagnosis can be confirmed by scraping the nail and:

• Looking at it under a microscope to identify the type of fungus

• Sending it for a culture (however, it may take up to 3 weeks to get results)

Treatment

Over-the-counter creams and ointments generally do not help treat this condition.

Prescription antifungal medicines taken by mouth may help clear the fungus.

• You will need to take the medicine for about 2 to 3 months for toenails; a shorter time for fingernails

• Fluconazole griseofulvin, terbinafine, and itraconazole are used to treat this condition.

• Your health care provider will do lab tests to check for liver damage while you are taking these medicines.

In some cases, the health care provider may remove the nail. Nails grow slowly. Even if treatment is successful, a new, clearer nail may take up to a year to grow in.

Expectations (prognosis)

The fungal nail infection is cured by the growth of new, non-infected nails.

Fungal nail infections may be difficult to treat. Medicines clear up fungus in about 50% of patients.

Even with successful treatment, it is common for the fungus to return.

Complications

• Fungal infections that return on the nails or in other parts of the body

• Permanent damage to the nails

• Skin infections, including paronychia

Calling your health care provider

Call your health care provider if:

• You experience persistent fungal nail infections

• Your fingers become painful, red, or drain pus

Prevention

Good general health and hygiene help prevent fungal infections.

• Do not share tools used for manicures and pedicures.

• Keep the skin clean and dry.

• Take proper care of your nails.

• Wash and dry your hands thoroughly after contact with any fungal infection.