February 20, 2017

Fungal Nails

What are fungal nail symptoms and signs?

Although fungal nails are usually cosmetic concerns, some patients do experience pain and discomfort. These symptoms may be exacerbated by footwear, activity, and improper trimming of the nails.

There are many species of fungi that can affect nails. By far the most common, however, is called Trichophyton rubrum (T. rubrum). This type of fungus has a tendency to infect the skin (known as a dermatophyte) and manifests in the following specific ways.

  • Starts at the ends of the nails and raises the nail up: This is called "distal subungual onychomycosis." It is the most common type of fungal infection of the nails in both adults and children (90% of cases). It is more common in the toes than the fingers, and the great toe is usually the first one to be affected. Risk factors include older age, swimming, athlete's foot, psoriasis, diabetes, family members with the infection, or a suppressed immune system. It usually starts as a discolored area at a corner of the big toe and slowly spreads toward the cuticle. Eventually, the toenails will become thickened and flaky. Sometimes, you can also see signs of athlete's foot in between the toes or skin peeling on the sole of the foot. It is often accompanied by onycholysis. The most common cause is T. rubrum.
  • Starts at the base of the nail and raises the nail up: This is called "proximal subungual onychomycosis." This is the least common type of fungal nail (about 3% of cases). It is similar to the distal type, but it starts at the cuticle (base of the nail) and slowly spreads toward the nail tip. This type almost always occurs in people with a damaged immune system. It is rare to see debris under the tip of the nail with this condition, unlike distal subungual onychomycosis. The most common cause is T. rubrum and non-dermatophyte molds.
  • Yeast onychomycosis: This type is caused by a yeast called Candida and not by the Trichophyton fungus named above. It is more common in fingernails and is a common cause of fungal fingernails. Patients may have associated paronychia (infection of the cuticle). Candida can cause yellow, brown, white, or thickened nails. Some people who have this infection also have yeast in their mouth or have a chronic paronychia (see above) that is also infected with yeast.
  • White superficial onychomycosis: In this nail condition, a doctor can often scrape off a white powdery material on the top of the nail plate. This condition is most common in tropical environments and is caused by a fungus known and Trichophyton mentagrophytes.
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Reviewed on 2/13/2017