Published on May 10, 2024 at 8:00 / Updated on May 25, 2024 at 8:00

Onychomycosis is a fungal nail infection. It can affect fingernails and toenails, but is more common in toenails. It sometimes accompanies athlete's foot, a fungal infection of the skin on the foot.

Onychomycosis will change the appearance of the nail and can cause pain. There may be debris under the nail and a white or yellow discolouration of the affected area of the nail. An infected nail may:

  • Appear brittle
  • Change shape
  • Have crumbling edges
  • Become loose
  • Become thick
  • Become dull and lackluster

Causes and triggers

Onychomycosis is a fungal infection, which means that it is caused by a microscopic fungus in the nail. It is usually acquired by walking barefoot in public areas or by sharing nail care tools.

This infection is more common in adults than in children, and is more prevalent in men. Other risk factors include:

  • Tiny cuts on the skin and around the nails
  • Nail diseases or deformities
  • Frequenting public swimming pools or living with someone who has the infection
  • Frequent exposure to moisture
  • Diabetes, poor circulation or a weakened immune system


While onychomycosis is usually harmless, it is somewhat challenging to treat. As a result, individuals whose symptoms are mild sometimes choose to forgo treatment altogether. However, in addition to preventing the infection from spreading to other nails, treatment can also prevent transmission.

Below are measures that can be taken at home to help manage the infection and prevent reinfection:

  • Dry skin carefully after showering or bathing
  • Keep nails clean and short
  • Avoid sharing nail care tools (e.g., nail clipper, nail file)
  • Remove shoes when possible to allow the skin to breathe
  • Avoid walking barefoot in public areas

In addition to these measures, there are products available to treat and eliminate the infection. Since over-the-counter products are not very effective, the use of prescription medication is recommended. These are either taken by mouth or applied directly on the nail. Medication in the form of tablets that are swallowed are usually most effective, but tend to cause more side effects. Treatment can last from a few weeks to several months depending on the medication and the area affected.

The infected part of the nail will never look the same again, even after completing treatment. Once the nail grows back, the affected part can be trimmed and the new nail will look normal. There is a chance that the infection will come back or that the treatment will not be successful. If this happens, your health professional may prescribe a different treatment or refer you to a specialist.

When should I see a medical professional?

  • If you have symptoms that look like onychomycosis
  • If there is no improvement after completing the treatment prescribed by your healthcare professional

For more information:

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