What is athlete's foot?

Athlete's foot, or tinea pedis, is a common fungal infection of the foot caused by a group of fungi called dermatophytes (also known as ringworm) that colonise the skin. It is a contagious condition that can be spread by direct or indirect contact with the infected skin.

Fungal infection

Any inflammatory condition caused by a fungus, a certain type of microscopic organism that includes yeasts, moulds and mushrooms.

Fungi

An organism from the fungi kingdom, which is a separate group to plants or animals, and includes yeasts, moulds and mushrooms. Fungi feed on organic matter.

Causes

Athlete's foot is caused by a group of fungi called dermatophytes. They use keratin, a component of skin, as an energy source. The severity of your response depends on the species and strain of dermatophyte causing the infection.

Microscopic illustration of Epidermophyton floccosum.Microscopic illustration of Epidermophyton floccosum, a type of dermatophyte. 

Fungi

An organism from the fungi kingdom, which is a separate group to plants or animals, and includes yeasts, moulds and mushrooms. Fungi feed on organic matter.

Risk factors

Risk factors for athlete's foot include:

  • Damp, humid conditions, such as wearing damp socks;
  • Walking barefoot in public areas such as locker rooms and communal showers or pools;
  • Close contact with an infected person or animal;
  • Sweaty feet confined in tight shoes, and;
  • Having a weakened immune system

Immune system

The organs and cells involved in protecting the body against infection.

Signs and symptoms

In athlete's foot, itchy blisters containing a clear fluid appear, usually between the toes. Other presentations of athlete's foot include:

  • Pustules or blisters on the sides of the feet (caused by Tinea intrerdigitale);
  • Ringworm-like patches on the top of the foot;
  • Dry, patchy scales on the sole of the foot (chronic hyperkeratotic tinea), and;
  • Dry, patchy scales on the whole of the sole, heel and sides of the foot (extensive hyperkeratotic tinea, usually caused by Tinea rubrum).

Athlete's foot can appear as blisters, pustules, or dry and patchy scales on the sole or sides of the foot.Athlete's foot. 

Pustules

A small skin blister that contains pus.

Methods for diagnosis

Potassium hydroxide exam

A scraping of your skin from the affected area is added to potassium hydroxide (KOH) and examined under a microscope. KOH destroys non-fungal cells, making it easier to see if any fungal cells are present.

Skin biopsy

A skin biopsy is performed only when other skin infections have to be ruled out.

Skin biopsy

A diagnostic procedure in which a sample of skin is removed and tested for abnormalities including cancer and infection.

Types of treatment

Athlete's foot is treated with antifungal creams such as ketoconazole and terbinafine that are applied directly to the affected area. Oral antifungal medications such as fluconazole are used for infections that do not respond well to topical cream. Treatment for some time after symptoms have subsided is needed to prevent the tinea's return.

Athlete's foot can be treated with a topical antifungal cream. 

Antifungal

A medication that kills fungi or inhibits their growth.

Potential complications

Antifungal side effects

Oral antifungal medications can cause nausea and liver damage if used for a prolonged period of time. Antifungals applied to the skin can cause itching and a burning sensation.

Contagion

Tinea spreads easily to other parts of the body. It can also result in breaks in the skin that cause permanent scarring, or lead to bacterial infections.

Antifungal

A medication that kills fungi or inhibits their growth.

Prognosis

Although athlete's foot can usually be cured, it is common for it to come back. If athlete's foot keeps recurring, it is possible the fungus is present on another part of your body that you have not been treating, particularly under the nails.

Fungus

An organism from the fungi kingdom, which is a separate group to plants or animals, and includes yeasts, moulds and mushrooms. Fungi feed on organic matter.

Prevention

Maintaining good hygiene by washing and drying properly, washing linen and towels in hot water and not sharing them with others can help prevent the spread of athlete's foot. You can reduce your risk of infection, and infection of others, by not walking barefoot in public showers or spaces such as gyms and pools.