Nail Fungus: Prevention, Causes and Treatment

Nail fungus, also known as onychomycosis, is an infection of the fingernail or toenail that can cause the nail to become discolored and brittle. One or more nails can be affected, and it can vary in severity. Treating nail fungus is challenging and takes time.

What causes nail fungus?

Nail fungus results from fungi that infect the skin, known as dermatophytes. Yeast and mold can also cause nail infections. Fungi commonly infect the toes, and yeast infections typically affect the fingers. Athlete’s foot is a common cause of toenail fungus.

What are the risk factors for nail fungus?

Anyone can get nail fungus. It can be more common in older adults over age 60 and occurs more commonly in men than women. There may be a higher risk of getting nail fungus with:

  • Athlete’s foot
  • Nail injury
  • Diabetes
  • Poor blood circulation or peripheral vascular disease
  • Psoriasis
  • Weakened immune systems
  • Tight shoes
  • Walking barefoot in damp community areas like pools, gyms, and locker rooms
  • Sweating heavily

Symptoms of nail fungus

Nail fungus may affect one or more nails. It is more common in toenails than fingernails. Signs of nail fungus include:

  • White or yellow discoloration
  • Brittle, crumbling nail edges
  • Misshapen nails
  • Odor
  • Thickened nails
  • Painful nails
  • Nail separates from the nail bed
  • Nails crack or break

How is nail fungus diagnosed?

Nail fungus can be confused with other nail conditions. If you are unclear if you have nail fungus, contact your healthcare provider. Your provider will examine your nails for signs of fungus or other causes that can look like fungal infections.

Your provider can take a sample of the nail to test for fungal spores. This will help determine what type of fungus is causing the infection and the best way to treat it. Testing can take a few weeks to complete because it is typically done by growing a culture. This helps ensure appropriate treatment and that the cause is not yeast, bacteria, or another disease.

Treating and managing nail fungal infections

Treating nail fungus can be a challenge. If you have tried over-the-counter remedies without success, speak with your healthcare provider. Your provider may refer you to a dermatologist for further treatment. Treatments vary based on the severity of the fungal infection, and it can take several months of treatment to see improvement. Even after improvement, re-infection is common.

Antifungal medications are generally the first line of treatment for nail fungus. Medications by prescription are either oral or topical form. In some cases, both types may be necessary as a combined therapy.

Oral antifungal drugs are the first choice because they work faster than topical medications. These medications treat the nail as it grows, so a new healthy nail grows in as the infection grows out. This regimen takes about six to 12 weeks, and results are visible when the nail is fully re-grown, which can take a few months.

Oral antifungal medications have less success in adults over 65. Bloodwork may be necessary to monitor for side effects like liver damage. These medications are not for people at risk for liver damage, liver disease, or heart failure. Oral antifungals include itraconazole (Sporanox) or terbinafine (Lamisil).

Medicated ointments are directly applied and can soak into the nail. This option may be more effective if the nails are thin, but creams tend to have a harder time getting through the nail to treat the fungus.

Medicated nail polish is also available and is applied to the nails daily. After seven days, remove the polish, and repeat the process. Unfortunately, this treatment may take up to a year for improvement.

Thinning the nails may be needed to help topical treatments be more effective. It can also help reduce pain and pressure caused by the deformed nail. You can use a urea-containing cream to soften the nail before trimming or filing down the extra thickness.

Caution: Avoid this if you have circulation issues, diabetes, or other concerns about trimming toenails.

Your provider may also remove the nail to apply medications to the site. In other cases, permanent nail removal may be necessary if the infection is severe or extremely painful.

How can I prevent getting nail fungus?

You can prevent nail fungus or re-infections by:

  • Wear shoes made of breathable material.
  • Wear sweat-absorbing socks or change your socks during the day.
  • Wash your hands and feet regularly, particularly after touching an infected nail.
  • Use disinfectant in old shoes or throw them away.
  • Be mindful of using a nail salon that sterilizes tools after each customer.
  • Stop using nail polish or artificial nails.
  • Cut nails straight across, and file rough edges or thickened areas, then disinfect nail clippers.
  • Avoid going barefoot in hotel rooms, public showers, locker rooms, swimming areas, etc.
  • Do not share the same location as someone else with nail or foot fungus, even a family member.
  • Dry your feet thoroughly after showering, swimming, or bathing.
  • Do not wear the same shoes two days in a row.
  • Take your shoes off as much as possible.
  • Do not share socks or shoes.
  • Avoid damaging nails.

Key take-aways:

Nail fungus is a fungal infection of the finger or toenails that can affect one or multiple nails.

It is challenging to treat. Over-the-counter medications may not be effective.

Nail fungus can leave people feeling uncomfortable about the appearance of their nails as it can often be unsightly.

Your healthcare provider will likely need to provide you with a prescription, which will take time to improve.


Mayo Clinic. Nail fungus.

National Library of Medicine. Nail fungus: Overview.

Cleveland Clinic. Toenail Fungus.

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