Fungal nail infection is an infection of the nails by a fungus.

The body normally hosts a variety of bacteria and fungi. Some of these are useful to the body. Others may multiply rapidly 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
• Tinea capitis

Fungal infections also include yeast-like fungi such as candida. Candida yeast infections include:

• Cutaneous candidiasis
• Diaper rash
• Oral thrush
• Some cases of genital rashes

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 frequent public swimming pools, gyms, or shower rooms -- and people who perspire a great deal -- commonly have mold-like infections. The fungi that cause them thrive in warm, moist areas.

The following increase the risk of a fungal infection:

• Getting minor skin or nail injuries
• Having moist skin for a long time
• Wearing closed-in footwear

• Nail changes on one or more nails (usually toenails):
  • Brittleness
  • Change in nail shape
  • Crumbling of the nail
  • Debris trapped under the nail
  • Discoloration
  • Loosening (detaching) of the nail
  • Loss of luster and shine
  • Thickening

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

The diagnosis can be confirmed by scraping the nail for a culture, or a microscopic examination to identify the type of fungus.

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

Prescription antifungal medicines taken by mouth may help clear the fungus in about 50% of patients. However, such medicines can cause side effects or may interfere with other medications. Some of the oral medications used to treat fungal infections of the nail can harm the liver.

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.

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

Fungal nail infections may be difficult to treat. Even with successful treatment, it is common for the fungus to return.

• Fungal infections that return on the nails or in other parts of the body
• Permanent damage to the nails
• Skin infections, including paronychia

Call your health care provider if:

• You experience persistent fungal nail infections
• Your fingers become painful, red, or drain pus

Good general health and hygiene help prevent fungal infections.

• Keep the skin clean and dry.
• Take proper care of your nails.
• Wash and dry your hands thoroughly after contact with any fungal infection.