Overview

Athlete's foot is the most common fungal infection in developed countries, affecting up to 70 percent of people at some time in their lives. The condition easily spreads in public places such as communal showers, locker rooms and fitness centers. Usually the condition affects the spaces between your toes, but it can spread to your toenails and the soles and sides of your feet. The infection can also involve your palms, groin or underarms. Although it occurs primarily in adults, athlete's foot can also affect children.

Signs and Symptoms

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

• Itching, stinging and burning between your toes, especially the fourth and fifth ones
• Itching, stinging and burning on the soles of your feet
• Blisters
• Cracking and peeling skin, especially between your toes and on the soles of your feet
• Foul odor
• Thickened skin
• Nails that are thick, crumbly, ragged, discolored or pulling away from the nail bed

Causes

Scientists have discovered that Athlete's Foot is caused by a group of fungi called dermatophytes. The dermatophyte most often implicated in athlete's foot is Trichophyton rubrum. The next most common is Trichophyton mentagrophytes, followed by Epidermophyton floccosum.

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.

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 in between. Damp socks increase the risk. The infection isn't found as often in areas of the world where shoes aren't worn. Warm, humid settings 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. 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.

Those who are vulnerable include people with weakened immune systems, for example people with diabetes or HIV/AIDS. People with atopic dermatitis, a chronic, inherited skin disease characterized by itchy, inflamed skin, also are more susceptible than others. Fungal infections of the foot become more common with age. There also may be a genetic predisposition for athlete's foot.

When to seek Medical Advice

If you notice a foot rash that doesn't improve within 2 weeks with self-care steps, then see your doctor. See someone sooner if you notice excessive redness, swelling, drainage or fever.

Screening and Diagnosis

Your doctor will want to determine if your symptoms are caused by athlete's foot or by another skin disorder, such as dermatitis or psoriasis.
You probably will be asked about exposure to contaminated areas or contacts with people who have athlete's foot.
Your doctor may take skin scrapings or fluid samples from your foot to view them under a microscope to identify a fungus within minutes. If the sample shows 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, and it may take weeks to get results. 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 antifungal ointment, lotion, powder or spray. Most infections respond well to these topical agents, which include:

• Clotrimazole (Lotrimin)
• Terbinafine (Lamisil AT)

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)

Prevention

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

1. Keep your feet dry, especially between your toes.
2. Wear socks that are made of natural material, such as cotton or wool.
3. Change socks and stockings regularly. If your feet sweat a lot, change your socks twice a day.
4. Wear light, well-ventilated shoes. Avoid shoes made of synthetic material, such as vinyl or rubber.
5. Alternate pairs of shoes so that they can dry over 2 to 3 days.
6. Wear waterproof sandals or shower shoes in communal showers, pools, fitness centers and other public areas.
7. Use an antifungal powder daily.
8. Don't borrow shoes.