Footwear Dermatitis
Footwear Dermatitis
Shoe dermatitis is relatively common with estimates of its prevalence among patch-tested patients up to 24.2%. And no wonder. The environment within a shoe—warm and occlusive—is perfect for promoting perspiration. In turn, the moist conditions help leach and disseminate the many potential sensitizers from shoe materials. Concomitantly, the moisture facilitates skin absorption. The friction that shoes impose on the feet further favors the development of allergic contact dermatitis (ACD). It’s almost difficult to conceive of a situation more optimal for promoting sensitization and for inhibiting healing of dermatitis.
Causes of footwear dermatitis?
Both natural and synthetic rubber and sometimes a combination of both may be found in shoes. Rubber box-toe shoes/boots have been reported as the most common cause of shoe dermatitis, but rubber is also used in other footwear such as sneakers, tennis shoes, slippers, boots, sandals, and flip-flops. Furthermore, rubber cements are used in joining shoe uppers, the outer leather and linings. Most rubber allergies are related to chemicals added during the processing of the latex—typically oxidants to slow degradation of the polymer and accelerators to speed the rate of vulcanization.
What potential allergens cause dermatitis in footwear?
In the NACDG study of shoe dermatitis, rubber chemicals considered as a group, which included carba mix, thiuram mix, mercaptobenzothiazole, mercapto mix, mixed dialkyl ureas, and black rubber mix, were the most common cause of shoe dermatitis (40.4%). Likewise, rubber chemicals are common shoe allergens in Brazil, Australia, and Britain. Other chemical accelerators to test for in patients with shoe dermatitis include thioureas, diphenylguan-idine, diaminodiphenylmethane, 4,4-dithiodimorpholine, cyclohexyldithiophthalimide, and hydroquinone monobenzylether.
How to avoid contact?
When possible, patients should wear shoes that do not contain the allergen causing their shoe dermatitis. Patients allergic to the chromate used to tan leather will benefit from wearing chromium-free leather shoes. If such shoes cannot be obtained, switching to a new pair of leather shoes every few months has been recommended as has wearing two pairs of socks and alternating shoes. Vegetable-tanned shoe are another alternative, and shoes from synthetic materials are readily available. An option for patients with rubber allergies is to replace the insoles of their shoes with cork, composite or felt applied with a nonrubber cement. Socks may be worn as a barrier, but it is best if they are changed frequently. Successful use of barrier creams has been reported, but such creams have also been reported to worsen dermatitis. Good skin care that includes moisturizing emollients or humectants is an important adjunct to avoidance. Over-the-counter products should be used before escalating treatment to prescription medications. Typically, systemic corticosteroids would be used only after more conservative treatment has failed. Treatment with an antibiotic may be needed if the skin becomes infected. As with any contact dermatitis, however, the most important part of management is perhaps patient education, and we at SmartPractice are here to help you insure that your patients are comfortable about kicking off their shoes and dancing in their dermatitis-free feet at all those holiday galas and beyond!
Additional resources
Matthys E, Ahir A, Ehrlich A. Shoe allergic contact dermatitis. Dermatitis 2014; 25(4):163-170
Thyssen JP, Jellesen MS, Moller P, et al. Allergic chromium dermatitis from wearing ‘chromium free’ footwear. Contact Dermatitis 2014;70:183-192
Corazza M, Baldo F, Ricci M, Sarno O, Virgili A. Efficacy of new barrier socks in the treatment of foot allergic contact dermatitis. Acta Derm Venereol 2011;91:68-69
Smith RG. Shoe dermatitis: causes, prevention, and management. Podiatry Management 2008; October:189-198. www.podiatrym.com
Warshaw EM, Schram SE, Belsito DV, et al. Shoe allergens: Retrospective analysis of cross sectional data from the North American
Contact Dermatitis Group, 2001–2004.” Dermatitis 2007;18(4):191-202
Freeman S. Shoe dermatitis. Contact Dermatitis 1997;36:247-251
U.S. Department of Health and Human Services (Household Products Database) https://householdproducts.nlm.nih.gov/
Contact Dermatitis Institute Allergen Database http://www.contactdermatitisinstitute.com/database.php
