Nail Fungus

Nail fungus is a fungal infection in one or more of your nails. An infection with nail fungus may begin as a white or yellow spot under the tip of your fingernail or toenail. As the nail fungus spreads deeper into your nail, it may cause your nail to discolor, thicken and develop crumbling edges — an unsightly and potentially painful problem.

An infection with nail fungus may be difficult to treat, and it may recur. But medications are available to help clear up nail fungus.

There are different classifications of nail fungus — depending on type of fungus and manifestation — which may have somewhat different signs and symptoms. In general, however, you may have a nail fungal infection — also called onychomycosis (on-i-ko-mi-KO-sis) — if one or more of your nails are:

  • Thickened,Brittle, crumbly or ragged
  • Distorted in shape
  • Dull, with no luster or shine
  • A dark color, caused by debris building up under your nail

Infected nails also may separate from the nail bed, a condition called onycholysis. You may feel pain in your toes or fingertips and detect a slightly foul odor. 
When to see a doctor?

Once a nail fungal infection begins, it can persist indefinitely if not treated. See your doctor at the first sign of nail fungus, which is often a tiny white or yellow spot under the tip of your nail.
Nail fungal infections are typically caused by a fungus that belongs to a group of fungi called dermatophytes. But yeasts and molds also can be responsible for nail fungal infections.
What are fungi?

Fungi are microscopic organisms that don't need sunlight to survive. Some fungi have beneficial uses, while others cause illness and infection.
All of these microscopic organisms:
Live in warm, moist environments, including swimming pools and showers. Can invade your skin through tiny visible or invisible cuts or through a small separation between your nail and nail bed. Cause problems only if your nails are continually exposed to warmth and moisture — conditions perfect for the growth and spread of fungi

Aging is the most common risk factor for nail fungus for several reasons, including:
Nail fungus tends to affect men more often than it does women, particularly those with a family history of this infection. 
Diminished blood circulation. More years of exposure to fungi. Nails may grow more slowly and thicken with age, making them more susceptible to infection.

Other factors that can increase your risk of developing nail fungus include:Toenails often are confined in a dark, warm, moist environment inside your shoes — where fungi can thrive. Diminished blood circulation to the toes as compared with the fingers makes it harder for your body's immune system to detect and eliminate the infection.

Risk factors:
Diminished blood circulation
More years of exposure to fungi
Nails may grow more slowly and thicken with age, making them more susceptible to infection
Perspiring heavily
Working in a humid or moist environment
Having the skin condition psoriasis
Wearing socks and shoes that hinder ventilation and don't absorb perspiration
Walking barefoot in damp public places, such as swimming pools, gyms and shower rooms
Having athlete's foot (tinea pedis)
Having a minor skin or nail injury, a damaged nail, or another infection
Having diabetes, circulation problems or a weakened immune system


Nail fungus can be painful and may cause permanent damage to your nails. It also may lead to other serious infections that can spread beyond your feet if you have a suppressed immune system due to medication, diabetes or other conditions. Fungal infections of the nail pose the most serious health risk for people with diabetes and for those with weakened immune systems, such as people with leukemia or AIDS or organ transplant recipients.

If you have diabetes, your blood circulation and the nerve supply to your feet can become impaired. You're also at greater risk for cellulitis, a potentially serious bacterial skin infection. Therefore, any relatively minor injury to your feet — including a nail fungal infection — can lead to a more serious complication, requiring timely medical care. See your doctor immediately if you suspect nail fungus.