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Foot Rash Can Be a Shoe-In

Study finds turning heels into pricey patch tests pinpoints allergies

SATURDAY, Feb. 9, 2002 (HealthDayNews) -- This discovery would probably send "Sex and the City" shoe maven Carrie Bradshaw into a three-episode tailspin.

Nevertheless, doctors say treating a stubborn foot rash might require cutting up those pricey designer heels, and turning them into a high-style medical patch test.

Indeed, that's the conclusion of a study that Cleveland Clinic dermatologist Dr. James S. Taylor presented recently at a meeting of the American Contact Dermatitis Society.

Sometimes, tackling a stubborn case of foot eczema or dermatitis means looking towards a shoe allergy. That, in turn, could require pulling apart your favorite boot, loafer or pump to create a patch test for the suspected components, he says.

"Shoe allergies are not extremely common, but they are not rare, and without a specific patch test they can be difficult to diagnose," says Dr. Ted Daly, an associate professor of dermatology at Nassau University Medical Center who was not involved in Taylor's study.

The problem, says Daly, is that too often the common chemical patch tests used to test for a shoe allergy aren't complete enough, so the results come up negative.

"Then shoe allergy is ruled out," Daly says. "But in reality, you just haven't tested for the right allergens."

Sometimes, Taylor adds, patients can go for months or even years with a red, itchy, painfully swollen foot rash, simply because they weren't tested properly and the allergy wasn't diagnosed.

That was the case for at least one patient, a 45-year-old man with chronic, painful foot dermatitis who eventually became the focus of Taylor's study.

Although all the standard tests for shoe allergy came up negative, Taylor suspected one of the shoe's components was causing the problems.

To find out which one, he asked the man to bring in three pairs of the shoes he commonly wore. Taylor then dissected the shoes, and cut out several pieces from different areas that touched the foot. The postage-stamp size snippets were then soaked in water for 10 minutes, and applied to the skin for a traditional "patch" test. The test was left in place for 96 hours.

The final result: The same red, itchy rash appeared on at least one patch test site, indicating the patient tested positive for an allergy to mercaptobenzothiazole, a chemical found in the rubber component of the shoes.

Once the man threw away the shoes and looked for styles that avoided that component, Taylor says the dermatitis cleared.

A study of 55 patients published in the journal Contact Dermatitis in 1997 found shoe allergies commonly go undiagnosed for about five years. In 33 percent of the patients, the problems lasted longer than five years; for up to 11 percent, they persisted 15 years or longer.

Sometimes a shoe allergy can seem obvious, like "when the rash follows the line of the design," Daly says. Other times it can be subtle, and caused by components you wouldn't even think would touch your feet.

"Things like glue used between the layers of the shoe, or grommets used in the laces, or sometimes even the laces themselves can be the source of the problem," Daly says.

Among the most common shoe allergens, he says, are dyes, adhesives, vinyl or other "fake" leathers used to make the shoes or the linings, or rubber in the shoe.

Now if you're thinking socks or pantyhose can help you avoid problems, guess again. Daly says the porous quality of most socks and all pantyhose means the allergen can penetrate, particularly if feet get hot and sweaty.

If you suspect your shoes might be behind your red, itchy, sore feet, doctors say the easy answer is to simply toss your shoes and look for a different style by a different company.

If your foot dermatitis is severe, Taylor recommends canvas shoes or sneakers until the rash clears. In extreme cases, he says, wearing wood or plastic shoes may be necessary.

Doctors can also prescribe topical ointments to speed healing, and aluminum chloride preparations to reduce sweating.

Should you decide to slice up those pricey pumps and go for the patch test, Daly says the results can be used to find shoes that don't have the offending components.

"Once you do find out which shoe components are causing you problems, you can contact shoe manufacturers directly, and ask if their shoes utilize the offending allergen, " he says.

What To Do

For a tip sheet on the symptoms of contact dermatitis, visit the McKinley Health Center.

For more information on contact rashes, visit The American Academy of Dermatology.

To learn how to contact shoe manufacturers, visit the Fashion Footwear Association of New York .

SOURCES: Interviews with James S. Taylor, M.D., head, section of industrial dermatology, department of dermatology, Cleveland Clinic Foundation, Cleveland; Ted Daly, M.D., associate professor, dermatology, Nassau University Medical Center, and dermatologist, Garden City Dermatology, New York City; December 2001 study presentation, American Contact Dermatitis Society.
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