What is causing my ugly toenail fungus and what can I do about it?

By Stanley Cyran, MD, a dermatologist at PMG Glisan Dermatology. February 2017.

Fungal infection of the nails is known as onychomycosis. Onychomycosis may involve any portion of the nails of the fingernails or toenails and can cause pain, discomfort, and disfigurement. It can occasionally produce serious physical and occupational limitations. It is increasingly common with age and rare in children. Individuals with diabetes are particularly at risk for complications from toenail problems.

Clinical features of onychomycosis

Onychomycosis may affect one or more toenails and/or fingernails and most often involves the great toenail or the little toenail. Patients with onychomycosis may present with the following:

  • Distal lateral onychomycosis: A white or yellow opaque streak appears at one side of the nail or the end of the nail or both. The nail can become thickened with crumbling debris underneath the nail.
  • Superficial white onychomycosis: Flaky white patches and pits appear on the top of the nail plate.
  • Proximal subungual onychomycosis: Yellow spots appear in the half-moon (lunula).
  • Onychoma or dermatophytoma: This is a thick localized area of infection in the nail plate.
  • Complete destruction of the nail.

What other conditions can look like onychomycosis

Causes of onychomycosis

Onychomycosis often results from untreated tinea pedis (athlete’s foot) or tinea manuum (fungus infection of the hand). It may also follow an injury to the nail.

Onychomycosis can be caused by:

  • Superficial skin fungus such as Trichophyton rubrum (T rubrum), or Trichophyton interdigitale. These are the organisms that usually cause athlete’s foot and jock itch.
  • Yeasts such as Candida albicans—the most common cause of yeast infections.
  • Molds especially Scopulariopsis brevicaulis and Fusarium species.
  • Onycholysis—injury to the nail
  • Onychogryphosis (nail thickening and scaling under the nail), common in the elderly.

How is onychomycosis diagnosed?

The diagnosis of onychomycosis can be confirmed with clippings taken from the affected nail(s) and sent for culture (to grow out the organism that is infecting the nail) or by direct visualization of the organism under a microscope.

How is onychomycosis treated?

Nail infections are very stubborn and difficult to treat. Once the fungus gets into the nail, it is difficult eradicate it as it is protected by the thick nail plate from topically administered medications. Athlete’s foot creams, over-the-counter nail fungus preparations, and other home remedies are not likely to be effective.

Mild infections affecting less than 50% of one or two nails may respond to topical antifungal medications. Topical treatments include Ciclopirox olamine nail lacquer, which is painted on the nail daily and removed weekly with alcohol. The advantage of this treatment is that it is available generically and is less expensive, although it is not particularly effective. Efinacolazole topical solution and Tavaborole topical solution are newer treatments and much more effective (in the 30-40% range for treatment effectiveness) but are very expensive and not as readily covered by most insurance plans.

Oral medications can be more effective than topically applied medications, but they can also have additional risks and side effects. These include terbinafine, which is an inexpensive generic. It is usually taken for three months for toenail infections and two months for fingernail infections. Blood testing is usually done before and after starting treatment. It may take a year for the nail to grow out normally after completing treatment. Another medication called fluconazole can be taken once weekly, but may need to be continued for year or longer.

Devices used to treat onychomycosis

Non-drug treatment with laser avoids the side effects and risks of oral antifungal drugs. Lasers emitting infrared radiation are thought to kill fungi by the production of heat within the infected portion of the nail. Several lasers have been approved for this purpose by the FDA and other regulatory authorities. However, high-quality studies of efficacy are lacking.