Fungal infections can affect any part of the body. Fungi are normally present in and on the body alongside various bacteria. But when a fungus begins to overgrow, you can get an infection.

Onychomycosis, also called tinea unguium, is a fungal infection that affects either the fingernails or toenails. Fungal infections normally develop over time, so any immediate difference in the way your nail looks or feels may be too subtle to notice at first.

Why does it develop?

A fungal nail infection occurs from the overgrowth of fungi in, under, or on the nail. Fungi thrive in warm, moist environments, so this type of environment can cause them to naturally overpopulate. The same fungi that cause jock itch, athlete’s foot, and ringworm can cause nail infections.

Fungi that are already present in or on your body can cause nail infections. If you have come in contact with someone else who has a fungal infection, you may have contracted it as well. Fungal infections affect toenails more commonly than fingernails, likely because your toes are usually confined to shoes, where they’re in a warm, moist environment.

If you get a manicure or pedicure at a nail salon, be sure to ask how the staff disinfects their tools and how often they do it. Tools, such as emery boards and nail clippers, can spread fungal infections from person to person if they’re not sanitized.

Who’s at risk for fungal infections?

There are many different causes of fungal nail infections. Each cause has a treatment of its own. Although many of the causes of a fungal nail infection are preventable, some risk factors increase the likelihood of developing one. You’re more likely to develop a fungal nail infection if you:

  • have diabetes
  • have a disease that causes poor circulation
  • are over age 65
  • wear artificial nails
  • swim in a public swimming pool
  • have a nail injury
  • have a skin injury around the nail
  • have moist fingers or toes for an extended time
  • have a weakened immune system
  • wear closed-toe shoes, such as tennis shoes or boots

Older adults have a high risk for getting fungal nail infections because they have poorer circulation. The nails also grow more slowly and thicken as we age.

What does it look like?

A fungal infection of the nail may affect part of the nail, the entire nail, or several nails.

Common signs of a fungal nail infection include:

  • a distorted nail that may lift off from the nail bed
  • an odor coming from the infected nail
  • a brittle or thickened nail

What are common kinds of nail fungus?


- Distal subungual infection

Distal subungual infections are the most common type of fungal nail infection and can develop in both fingernails and toenails. When infected, the outer edge of the nail has a jagged appearance with white and/or yellow streaks across the nail.

The infection invades the nail bed and underside of the nail.

- White superficial infection

White superficial infections usually affect toenails. A certain type of fungus attacks the top layers of the nail and creates well-defined white spots on the nail.

Eventually these white patches cover the entire nail, which becomes rough, soft, and prone to crumbling. Spots on nail may become pitted and flaky.

- Proximal subungual infection

Proximal subungual infections are uncommon but can affect both fingernails and toenails. Yellow spots appear at the base of the nail as the infection spreads upward.

This infection can commonly occur in people with compromised immune systems. It can also result from minor injury to the nail.

- Candida infection

Candida yeasts cause this type of infection. It can invade nails previously damaged by a prior infection or injury. More commonly, Candida affects fingernails. It often occurs in people who frequently soak their hands in water.

These infections usually start by the cuticle around the nail, which becomes swollen, red, and tender to the touch. The nail itself may partially lift off the nail bed, or fall off completely.

How do I know if I have a fungal nail infection?

Because other infections can affect the nail and mimic symptoms of a fungal nail infection, the only way to confirm a diagnosis is to see a doctor. They’ll take a scraping of the nail and look under a microscope for signs of fungus.

In some cases, your doctor may send the sample to a lab for analysis and identification.

How is a fungal nail infection treated?

Over-the-counter products aren’t usually recommended to treat nail infections since they don’t provide reliable results. Instead, your doctor may prescribe an oral antifungal medication, such as:

Your doctor may prescribe other antifungal treatments, such as antifungal nail lacquer or topical solutions. These treatments are brushed onto the nail in the same way that you’d apply nail polish.

Depending on the type of fungus causing the infection, as well as the extent of the infection, you may have to use these medications for several months. Topical solutions aren’t generally effective in curing toenail fungal infections.

Tips to prevent fungal nail infections

Making a few simple lifestyle changes can help prevent a fungal infection of the nails. Taking good care of your nails by keeping them well trimmed and clean is a good way to prevent infections.

Also avoid injuring the skin around your nails. If you’re going to have damp or wet hands for an extended amount of time, you may want to wear rubber gloves.

Other ways to prevent fungal infections of the nails include:

  • washing your hands after touching infected nails
  • drying your feet well after showering, especially between your toes
  • getting manicures or pedicures from trustworthy salons
  • avoiding being barefoot in public places
  • reducing your use of artificial nails and nail polish

Long-term outlook

For some people, a fungal nail infection can be difficult to cure, and the first round of medication might not work. The nail infection can’t be considered cured until a new nail that’s free from infection has grown in.

Although this indicates that the nail is no longer infected, it’s possible for the fungal infection to return. In severe cases, there may be permanent damage to your nail, and it may have to be removed.

The main complications of a fungal nail infection are:

  • a resurgence of the infection
  • a permanent loss of the affected nail
  • a discoloration of the infected nail
  • the spread of infection to other areas of the body and possibly the bloodstream
  • the development of a bacterial skin infection called cellulitis

It’s especially important to see your doctor if you have diabetes and a fungal nail infection. People with diabetes have a greater risk for developing potentially serious complications caused by these infections. Talk to your doctor if you have diabetes and think you’re developing a fungal nail infection.