Runners & Foot Problems
by Robert Scheinberg, MD
Skin changes in the feet of runners are usually ecological in origin. In other words, the hot, humid climate of the foot, aggravated by the friction of running and the alkaline environment produced by sweat, allows germs to grow, promoting allergic reactions and worsening of noninfectious skin conditions.
This article will explain how you can recognize different types of athlete's foot and other foot problems of runners, what you can do to treat them yourself, and when you should go to your family doctor, podiatrist or dermatologist for treatment.
Most people think that fungus causes all itchy, scaly rashes of the foot. However, friction, chapping, allergy to shoe materials and even skin cancer can cause unpleasant foot symptoms in runners.
When fungus causes athlete's foot, you usually are bothered by itching and scaling between the toes. But itchy or painful blisters on the instep or diffuse scaling of the soles in the distribution of the area covered by a sandal also may be due to fungus. You can't avoid the fungus, which is on the floors of locker rooms and showers and on carpets in homes and hotel rooms. To prevent infection, dry between the toes after workouts, wear absorbent socks such as Thorlo® rather than cotton (which becomes saturated), and change out of wet shoes as soon as possible, not wearing them again until they dry out completely.
If you get itching and scaling of the feet, the first step is to try an antifungal cream. The best over-the-counter antifungals are miconazole (Micatin®), clotrimazole (Lotrimin®) and terbinafine (Lamasil®), which should be applied once or twice daily. Miconazole and clotrimazole are less expensive but must be used until the signs of infection are gone, while terbinafine can be used for 7-14 days and then stopped, since the medication stays in the skin, fighting the fungus, for a few weeks after it is discontinued. Applying any of the antifungals to the feet several times a week, especially before long runs, will reduce the chances of recurrence.
Antifungal creams and liquids can be applied to yellow, thickened toenails infected with fungus, but no external product cures more than 25% of onychomycosis, the medical name for toenails infected with fungus. The newer, oral medications itraconazole (Sporonox®) and terbinafine (Lamasil®) have much higher cure rates than the older oral antifungals such as griseofulvin (GrisPEG®, Fulvicin®) and usually need to be taken for only a few months under the supervision of a physician.
I usually recommend treating onychomycosis if it is producing pain from the thickened nail or if it is acting as a reservoir of fungus causing re-infection of the skin, or if a patient is sick and tired of looking at ugly nails. However, before you take oral medications for fungus, make sure your doctor has proven that you are indeed infected with fungus. About half of ugly, thickened, yellowed nails are due to the repeated trauma of running or to skin diseases such as psoriasis, eczema or lichen planus, or to medications such as isotretinoin (Accutane®), taken for severe acne. Your doctor should do a scraping of the material under the nails and send it for culture or look at it under a microscope to confirm that fungus is present.
Some runners develop mushy, white macerated skin between the toes. This type of athlete's foot is due to a mixture of bacteria and yeast living in moist toe webs. Antifungal creams and pills almost never cure this infection. Instead, make the area between the toes inhospitable to bacteria and yeast by making it dry and acidic. Vinegar soaks - one part white vinegar to 10 parts water, applied for five minutes, patted dry and then blow-dried until the skin is no longer moist - will usually eradicate the infection. Antifungal powders such as Zeasorb AF®, Micatin®, and Desitin® can then be used to keep the toe webs dry and prevent future fungal infection. Cornstarch should be avoided, since it is a growth medium for fungus, yeast and bacteria.
Runners who sweat profusely may get sharply edged but shallow pits on the skin of the sole. This is termed pitting keratolysis and is usually associated with especially foul-smelling feet. The cause of both the pits and the smell is bacteria that love to eat moist stratum corneum, the dead cell layer on the surface of the skin. Treatment consists of measures to reduce sweating such as tea soaks (two teabags in a cup of hot water added to lukewarm water in a basin) and prescription aluminum chloride solution (Drysol®) used along with antiseptic soaps, topical antibiotics such as clindamycin (Cleocin®) and absorbent socks changed frequently.
Itching athlete's foot that spares the spaces between the toes and fits the pattern of a part of the running shoe is usually caused by an allergy to shoe materials, or contact dermatitis. Leather, rubber, adhesive and coloring agents can all cause this nonfungal athlete's foot. Trial and error, changing running shoes or going to a dermatologist for allergy patch tests can find the exact cause of the rash and prevent it from coming back. Cortisone creams, over-the-counter or by prescription, can help the itching while determining the cause of the contact dermatitis.
People with a history of eczema or dry, itchy skin can get scaling of the feet which spares the toewebs. Preventing chapping by using moisturizers and cortisone creams can treat this type of athlete's foot, which is a type of atopic dermatitis. Scaling, blisters and painful pustules of the feet can also be due to the common skin condition psoriasis. Treatment for fungus does no harm to a patient with psoriasis or atopic dermatitis but, if the condition does not respond to self-medication in 2-3 weeks or if you are having intense pain, fever or tenderness, see a doctor. Any scaling patch that persists or bleeds has the possibility of being a skin cancer. A biopsy should be done if all measures by you and your physician have failed to clear the problem, especially if it is only on one foot.
FOOT PROBLEMS DUE TO TRAUMA:
Frictional forces can cause blisters, corns and calluses. Blisters are the result of shearing forces on the skin that result in the accumulation of fluid. Prevention by using petroleum jelly, absorbent (non-cotton) socks and well-fitted running shoes, which are not wet, is the best course. If you do get a blister, puncture it in several places with a sterile needle, releasing the fluid, and then apply anti- biotic ointment and a Band-Aid to let the roof of the blister act as a biologic bandage until the skin heals and the roof of the blister falls off.
Calluses are the response of the skin to shearing forces not intense enough to form a blister. They are of no consequence unless they are painful, which usually means there is a wart or corn at the base of the callus. I favor treating both corns and warts with salicylic acid plasters rather than surgery. These are applied at night after a pumice stone is used to remove dead skin. In the morning, the pumice stone is used again and a moisturizer is applied to reduce friction. Usually, the wart or corn becomes pain free within a few days. If not, I suggest you visit your family doctor, podiatrist or dermatologist for treatment with liquid nitrogen, laser or prescription wart treatments.
Robert S. Scheinberg, MD, is a member of the Dermatologist Medical Group of North County, Inc. and a Clinical Professor of Medicine/Dermatology at University of California at San Diego Medical Center.