Athlete's foot

Introduction

Athlete's foot is a common fungal infection that affects many people at some time in their lives. The condition easily spreads in public places such as communal showers, locker rooms and fitness centers.

Athlete's foot usually affects the spaces between your toes, but it can spread to your toenails and the soles and sides of your feet. Often, athlete's foot responds well to over-the-counter (nonprescription) treatments you can apply to your skin. More severe cases may require prescription medications.

Also called tinea pedis, ringworm of the foot and dermatophytosis, athlete's foot is closely related to other fungal skin conditions, most with similar names. Tinea is a type of fungus, and "pedis" is the Latin word for "foot." Other common tinea infections include:

• Ringworm of the body (tinea corporis). This form causes a red, scaly ring or circle of rash on the top layer of your skin.
• Jock itch (tinea cruris). This form affects your genitals, inner thighs and buttocks.
• Ringworm of the scalp (tinea capitis). This form is most common in children and involves red, itchy patches on the scalp, leaving bald patches.

Signs and symptoms

The signs and symptoms of athlete's foot can be numerous, although you probably won't have all of them:

• Itching, stinging and burning between your toes, especially the last two toes
• Itching, stinging and burning on the soles of your feet
• Itchy blisters
• Cracking and peeling skin, especially between your toes and on the soles of your feet
• Excessive dryness of the skin on the bottoms or sides of the feet
• Nails that are thick, crumbly, ragged, discolored or pulling away from the nail bed

 

Athlete's foot usually affects the spaces between your toes, but it can spread to your toenails and the soles and sides of your feet.

Causes

A group of mold-like fungi called dermatophytes causes athlete's foot. These organisms sprout tendril-like extensions that infect the superficial layer of the skin. In response to this fungal growth, the basal layer of the skin produces more skin cells than usual. As these cells push to the surface, the skin becomes thick and scaly. Most often, the more the fungi spread, the more scales your skin produces, causing the ring of advancing infection to form.

Risk factors

The organisms that cause athlete's foot thrive in damp, close environments created by thick, tight shoes that can pinch the toes together and create warm, moist areas between them. Damp socks and shoes increase the risk. Warm, humid conditions that promote heavy sweating favor its spread.

The fungus is carried on fragments of skin or other particles that contaminate floors, mats, rugs, bed linens, clothes, shoes and other surfaces. Plastic shoes in particular provide a welcoming environment for fungal growth and infection. Person-to-person contact is another means of transmission. Even household pets can pass along fungal infections. Although transmission can occur within a household, the infection is more commonly passed along in public areas — locker rooms, saunas, swimming pools, communal baths and showers. Not everyone who carries the fungus develops signs and symptoms of athlete's foot.

Although it occurs primarily in adults, athlete's foot can affect children. Men are more likely than women to develop athlete's foot. Vulnerability probably involves a genetic component, but those who are known to be more vulnerable include people with weakened immune systems, for example, people with diabetes or HIV/AIDS.

When to seek medical advice

If you have a rash on your foot that doesn't improve or worsens after you've taken self-care steps, see your doctor. See someone sooner if you notice excessive redness, swelling, drainage or fever. In addition, if you have diabetes and suspect you have athlete's foot, see your doctor.

Screening and diagnosis

Your doctor will want to determine if your signs and symptoms are caused by athlete's foot or by another skin disorder, such as dermatitis or psoriasis. You'll probably be asked about exposure to contaminated areas or contact with people who have athlete's foot.

Your doctor may take skin scrapings or fluid samples from your foot to view under a microscope to identify a fungus. If the sample shows a fungus, an antifungal medication is the usual treatment. If the test is negative but your doctor still suspects that you have athlete's foot, a sample may be sent to a laboratory to determine whether it will grow fungus under the right conditions. This test is known as a culture. Your doctor may also order a culture if your condition doesn't respond to treatment.

Complications

The fungal infection can create an environment that invites a secondary bacterial infection. By producing an antibiotic substance, the fungus can kill off vulnerable bacteria and favor the overgrowth of hardier, resistant types. In turn, the bacteria release substances that can cause tissue breakdown — soggy skin and painful eroded areas between the toes.

After an episode of athlete's foot, proteins might enter your bloodstream, leading to an allergic reaction that may cause an eruption of blisters on your fingers, toes or hands (dermatophytid reaction).

Treatment

For mild conditions, your doctor may advise you to apply a prescription or over-the-counter (nonprescription) antifungal ointment, lotion, powder or spray. Most infections respond well to these topical agents, which include:

• Terbinafine (Lamisil AT)
• Clotrimazole (Lotrimin AF)
• Miconazole (Micatin)

If your fungal infection is severe or doesn't respond to topical medicine, your doctor may give you a prescription oral medication. Oral medications include:

• Itraconazole (Sporanox)
• Fluconazole (Diflucan)
• Terbinafine (Lamisil)

According to the Food and Drug Administration (FDA), oral itraconazole and oral terbinafine may be linked to rare cases of liver failure and death. Oral itraconazole may weaken the heart's contractions and shouldn't be prescribed for people with a history of heart failure.

Your doctor may prescribe an oral antibiotic if you have an accompanying bacterial infection. In addition, your doctor may recommend wet dressings, steroid ointments, compresses or vinegar soaks to help clear up blisters or soggy skin.

Prevention

These tips can help you avoid athlete's foot or ease the symptoms if infection occurs:

• Keep your feet dry, especially between your toes. Go barefoot to let your feet air out as much as possible when you're home.
• Go with natural materials. Wear socks that are made of natural material, such as cotton or wool, or a synthetic fiber designed to draw moisture away from your feet.
• Change socks and stockings regularly. If your feet sweat a lot, change your socks twice a day.
• Wear light, well-ventilated shoes. Avoid shoes made of synthetic material, such as vinyl or rubber.
• Alternate pairs of shoes. This allows time for your shoes to dry.
• Protect your feet in public places. Wear waterproof sandals or shower shoes in communal showers, pools, fitness centers and other public areas.
• Treat your feet. Use an antifungal powder daily.
• Don't borrow shoes. Borrowing risks spreading a fungal infection.