Q. I would like to ask you about my problem of foot odor, which is worst when I wear shoes. What causes foot odor and what is the treatment for it? I hope you can help me.

— Lorna P., Cavite City

A. The underlying cause of foot odor or plantar bromhidrosis is sweat. The feet and the hands have more sweat glands than any other part of the body, so they can sweat profusely. In the hands, sweat evaporates but in feet that are enclosed in shoes, it doesn’t.  Sweat itself is odorless, but it softens the outer layer of the skin of the feet and creates a perfect environment for bacterial growth. The bacteria that attack the softened skin thrive on keratin—the protein that is plentiful in the cells of the skin—and produce isovaleric acid, which causes the odor.

The bacteria that flourish on the softened keratin in the skin of the feet are harmless microorganisms that normally reside on the skin. Sometimes, some other equally innocuous bacteria join the action. However, at times, disease-causing bacteria invade the area, produce infection, and add to the foul odor.

Occasionally, instead of bacteria, fungi invade the softened keratin. Since fungi thrive well in a damp environment, they produce eczematous skin lesions (e.g., athlete’s foot), and further add to the foul odor.

Plantar bromhidrosis is more common in males than in females. It is seen more often in young and middle-aged adults but it can be seen—though to a less extent—in the other age groups, including children. It has no racial predisposition. However, obesity is a predisposing factor.

Foot odor is relatively easy to control (i.e., compared to body odor that originates from the armpits).

To eliminate your problem, I suggest that you do the following:

1. Bathe or shower everyday. Scrub your feet thoroughly (with a brush, foot towel or loofah) paying particular attention to the soles and the webs of the toes. Dry your feet well after bathing.

2. Use several shoes and wear them alternately. The pairs not in use should be allowed to dry, preferably under the sun. Remove the innersoles from the shoes to speed up the drying. It’s best not to wear the same pair of shoes two days in a row to allow the pairs not being used to dry completely.

3. At home, use open slippers instead of shoes.

4. Replace your socks daily and wash them thoroughly after each use. Use socks that have been made from highly absorbent material like cotton. Synthetic materials absorb sweat poorly.

5. Dust your feet with drying powders—you can take your pick from many preparations available in the market— before you wear your socks and shoes.

Follow the above measures for a couple of weeks. If your problem has not been eliminated by then, I suggest you consult a dermatologist. There might be something else in your feet, such as an infection, that has to be attended to. At any rate, I’m sure a dermatologist can be of further help.

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