Ask Dr. K: How you can treat and prevent athlete’s foot

An early sign of infection is white scaly patches or fissures (small tears in the skin), especially between the toes. As the infection progresses, the skin may turn red and become itchy and moist. Small blisters may spread out across your foot. They then break and expose painful fissures that may swell. The infection may spread to the soles of your feet or to your toenails. If you touch your feet and then another part of your body, the infection may spread there as well.

There are several treatment options. For a mild infection, focus on foot hygiene. Wash your feet regularly and dry them thoroughly, especially between the toes. Apply an antifungal cream to the affected area and dust your socks and shoes with antifungal powder. Examples of medicines that are available over the counter are terbinafine (Lamisil), clotrimazole (Lotrimin), miconazole (Micatin) and tolnaftate (Tinactin). Many effective antifungal remedies are sold over the counter.

If you have a severe infection or don’t see improvement after two weeks of over-the-counter treatment, see a foot care specialist. He or she may prescribe a stronger topical medication for a longer period of time. He or she also may recommend a prescription medication to take by mouth. Some examples are terbinafine, itraconazole and fluconazole.

Watch for one dangerous complication of athlete’s foot: a bacterial infection called cellulitis. It causes a redness of the skin on the top of the foot (starting near the toes) and then spreads up the lower leg. The red area may be slightly tender, and a fever may develop. Bacteria live on the skin. When athlete’s foot causes a break in the skin, it allows bacteria to get under the surface of the skin and spread.

The best way to prevent athlete’s foot, or a recurrence of it, is by wearing sandals or shower shoes in locker rooms or pool areas. Fungi thrive in dark, damp environments, but the most common dark, damp environment your feet experience is not a locker room. It’s your shoe, particularly in warm or hot weather, when your feet sweat.

To avoid athlete’s foot, wash your feet at least once a day. Keep your feet dry the rest of the time. Put on clean socks every day, and change them more often if you sweat. Take your shoes off at home to give your feet a chance to “breathe.”

Dr. Komaroff is a physician and professor.

To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.