Shoe Allergy Causes and Concerns

Allergic rashes caused by shoes can affect the feet, especially the dorsal (top) surfaces. Contact dermatitis from an allergy to shoe material can also involve the feet.

Rashes on the feet are a common problem, with most people experiencing athlete’s foot (tinea pedis) as a cause of their symptoms. Tinea pedis may involve all surfaces of the feet, but most commonly involve the area between the toes. Symptoms include itching, burning, and stinging, but tinea pedis can also be asymptomatic.

People who experienced atopic dermatitis as children may develop eczema on the hands and feet as adults. Eczema on the feet is more likely to affect the plantar (bottom) surfaces.

Contact Dermatitis to Shoes

Contact dermatitis to shoes usually results in an itchy, blistering, or peeling rash, often on the top of the foot. The rash may also be present on the heels, but less commonly affects the instep of the foot and the areas between the toes.

Various studies show that contact dermatitis to shoes can affect anyone—children and adults, men and women, and various occupations. It is especially common among military personnel.

There are a number of different chemicals known to cause contact dermatitis as a result of shoes, the most common being various kinds of rubber compounds and chromate salts, which are used as tanning agents on leather products. Less common causes of shoe allergy include various glues, resins, metals, and pigments.

Rubber Compounds

Several rubber compounds can cause shoe allergy, and as a group, rubber compounds are the most common source of shoe allergy. These include thiuram mix, carba mix, mercaptobenzothiazole, mercapto mix, and black rubber mix. These chemicals are present in the sole of the shoes, and therefore shoe allergies from rubber compounds would usually present as itchy rashes on the bottom of the feet.

The exact chemical causing the rash can be identified with the use of patch testing; once identified, that specific chemical can then be avoided.

There are different types of shoes, or shoe inserts, that can be purchased in order to avoid contact with the material causing the shoe allergy. For instance, using wooden clogs or plastic shoes, or replacing rubber soles with cork inserts may be a way to avoid the chemicals causing the problem.

Chromate

Chromate salts are used in the tanning process for leather. This chemical is the most common cause of shoe allergy in military personnel, and in other professions as well (such as police, firefighters, construction workers, etc.).

Rashes from chromate exposure could occur on the top or bottom of the foot, depending on the location of the leather on the shoes. Avoidance of chromate means wearing non-leather shoes.

Glues and Resins

Butylphenol formaldehyde resin is a common cause of shoe allergy caused by glues and resins. This resin is used to glue together various parts of shoes, particularly leather and rubber parts in shoes. Rashes from butylphenol formaldehyde resin would usually be located on the top and sides of the feet, where the seams of the upper part of the shoe are present.

Avoidance of shoes that contain many pieces that are glued together, and instead wearing a shoe that is manufactured from a single piece of material, should prevent contact dermatitis from this resin.

Pigments and Metals

Less commonly, people can experience shoe allergy as a result of pigments or metals present in the fabric of the shoe. These could include chromate, cobalt, a dye called disperse blue 106, or other pigments. Rashes from pigments present in shoes would typically occur on the top and sides of the foot, where the skin is in contact with pigmented fabric.

Avoidance of shoes made of pigmented fabrics, particularly darker colors such as blues, greens, and blacks, should prevent contact dermatitis from pigments.