Athlete's foot

Definition

Athlete's foot is an infection of the feet caused by fungus. The medical term is tinea pedis or ringworm of the foot.

Alternative Names

Tinea pedis; Fungal infection - feet; Tinea of the foot; Infection - fungal - feet; Ringworm - foot

Causes

Athlete's foot occurs when a certain fungus grows on the skin of your feet. The same fungus may also grow on other parts of the body. However, the feet are most commonly affected, especially between the toes.

Athlete's foot is the most common type of tinea infection. The fungus thrives in warm, moist areas. Your risk for getting athlete's foot increases if you:

Wear closed shoes, especially if they are plastic-lined
Keep your feet wet for long periods
Sweat a lot
Develop a minor skin or nail injury

Athlete's foot is easily spread. It can be passed through direct contact or contact with items such as shoes, stockings, and shower or pool surfaces.

Symptoms

The most common symptom is cracked, flaking, peeling skin between the toes or on the side of the foot. Other symptoms can include:

Red and itchy skin
Burning or stinging pain
Blisters that ooze or get crusty

If the fungus spreads to your nails, they can become discolored, thick, and even crumble.

Athlete's foot may occur at the same time as other fungal or yeast skin infections such as jock itch.

Exams and Tests

Your health care provider can diagnose athlete's foot simply by looking at your skin. If tests are needed, they may include:

A simple office test called a KOH exam to check for fungus
Skin culture
A skin biopsy may also be performed with a special stain called PAS to identify fungus

Treatment

Over-the-counter antifungal powders or creams can help control the infection:

These contain medicine such as miconazole, clotrimazole, terbinafine, or tolnaftate.
Keep using the medicine for 1 to 2 weeks after the infection has cleared to prevent it from returning.

In addition:

Keep your feet clean and dry, especially between your toes.
Wash your feet thoroughly with soap and water and dry the area carefully and completely. Try to do this at least twice a day.
To widen and keep the web space (area between the toes) dry, use lamb's wool. This can be bought at a drugstore.
Wear clean cotton socks. Change your socks and shoes as often as needed to keep your feet dry.
Wear sandals or flip-flops at a public shower or pool.
Use antifungal or drying powders to prevent athlete's foot if you tend to get it often, or you frequent places where athlete's foot fungus is common (like public showers).
Wear shoes that are well-ventilated and made of natural material such as leather. It may help to alternate shoes each day, so they can completely dry between wearings. Do not wear plastic-lined shoes.

If athlete's foot does not get better in 2 to 4 weeks with self-care, or frequently returns, see your provider. Your provider may prescribe:

Antifungal medicines to take by mouth
Antibiotics to treat bacterial infections that occur from scratching
Topical creams that kill the fungus

Outlook (Prognosis)

Athlete's foot almost always responds well to self-care, although it may come back. Long-term medicine and preventive measures may be needed. The infection can spread to the toenails.

When to Contact a Medical Professional

Call your provider right away if:

Your foot is swollen and warm to the touch, especially if there are red streaks or pain. These are signs of a possible bacterial infection. Other signs include pus, drainage, and fever.
Athlete's foot symptoms do not go away within 2 to 4 weeks of self-care treatments.

References

Elewski BE, Hughey LC, Hunt KM, Hay RJ. Fungal diseases. In: Bolognia JL, Schaffer JV, Cerroni L, eds. Dermatology. 4th ed. Philadelphia, PA: Elsevier; 2018:chap 77.

Hay RJ. Dermatophytosis (ringworm) and other superficial mycoses. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 266.