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

The body normally hosts a variety of microorganisms, including 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:

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

Fungal nail infections are most often seen in adults. They often follow fungal infection of the feet. Fungal nail infections may be difficult to treat and may recur often. 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, because the fungi that cause them thrive in warm, moist areas.

The risk of getting a fungal infection is increased by closed-in footwear, prolonged moist skin, and minor skin or nail injuries.

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

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 anti-fungal 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 health medicines the patient is taking.

In some cases, the nail may be removed by the doctor. Nails grow slowly, so even if treatment is successful, a new, clearer nail may take up to a year to grow in.

Fungal nail infections may be difficult to treat and may become a reservoir for fungal organisms, causing them to return in the skin or nails. The fungal nail infection is cured by the growth of new, non-infected nails. Even with successful treatment, a relapse is common.

• Permanent damage to the nails
• Secondary skin infections, including paronychia
• Recurrent fungal infections of the nails or other parts of the body

Call your health care provider if you experience persistent fungal nail infections, or if the fingers become painful, red, or drain pus.

Good general health and hygiene help to prevent fungal infections. Keep the skin clean and dry. Take proper care of the nails (see treatment). Wash and dry the hands thoroughly after contact with any fungal infection.