Contact Dermatitis (Patch Testing)
Allergic Contact Dermatitis, a form of skin allergy which can mimic eczema, is a common cause of dermatitis in the United States and can be extremely frustrating for patients. It is also one of the few conditions which is completely curable if the offending allergen can be identified and avoided. Patch testing is the only definitive way to diagnose allergic contact dermatitis, which is a delayed-type hypersensivity reaction. This is in contrast to the immediate-type hypersensitivity. Urticaria and some food allergies are examples of immediate-type hypersensitivities. These are diagnosed by prick testing, the form of allergy testing commonly performed by allergists.
Patch testing is a more complex type of allergy test which generally requires 3 office visits over the course of one week. At the initial consultation visit, we will discuss the problem and determine which allergens would be worth testing. Once we determine which allergens to test for, an appointment is scheduled to apply the patches which remain on the skin under occlusion with hypoallergenic tape for 2 days. At 2 days, the patches are removed and an initial reading is performed. A final reading is performed between days 4-7 to evaluate any additional reactions. Once we determine which allergens have a positive and relevant reaction, we can generate a list of products which allow the patient to avoid the allergen. Although there is some degree of inconvenience for the patient during the week of testing, comprehensive patch testing can greatly increase quality of life if relevant allergens are identified and avoided.