Patch Testing

Testing for allergies in a dermatologist’s office is completely different from that in an allergist’s practice. In the latter, you may be tested for allergies to such substances as pollen, ragweed, and various foods. Dermatologists test for allergies to substances you touch (nickel in watchbands, preservatives in creams and lotions, hair dyes, fragrances, and so on). In other words, dermatologists do not test for allergies to things you consume or inhale. We test for allergies to things your skin comes in contact with.

In patch testing, several patches with multiple allergens (substances to which you may be allergic) are taped on your back. The area is marked for easy identification and taped to secure the patches in place. The patches are removed in 48 hours for the reading of preliminary results. Some allergies show up at a later time, hence a second visit 72 or 96 hours later is required. Patients cannot shower or wet the back for the duration of patch test.

The TRUE test for skin allergies is a panel used extensively in this country. This panel consists of 29 patches containing different chemicals commonly causing allergic reactions. Below you will find the list of allergens in the TRUE test, along with instructions on how to avoid these allergens.

Panel 1.1
Nickel Sulfate
Wool Alcohols
Neomycin Sulfate
Potassium Dichromate
Caine Mix
Fragrance Mix
Paraben Mix
Negative Control
Balsam of Peru
Ethylenediamine Dihydrochloride
Cobalt Dichloride

Panel 2.1
p-tert-Butylphenol Formaldehyde Resin
Epoxy Resin
Carba Mix
Black Rubber Mix
Cl Me- Isothiazolinone (MCI/MI)
Mercapto Mix
Thiuram Mix

Panel 3.1
Diazolidinyl urea
Imidazolidinyl urea
Quinoline mix

If the chemical causing the allergic reaction is identified, your doctor will discuss the ways to avoid the offending substance and provide you with written materials on the topic. Unfortunately, there is no cure for skin allergies. Only careful avoidance of substances responsible for your allergies can make things better.

Alexander Doctoroff, D.O., F.A.O.C.D.
Assistant Chief of Dermatology, Veterans Administration Medical Center
East Orange, New Jersey
Assistant Clinical Professor of Medicine,
University of Medicine and Dentistry of New Jersey.