Allergy Patch Testing Offers a Cure for Contact Dermatitis Eczema Memphis Dermatologist
by George Woodbury Jr. M.D. (05/14/2023)
Since 2004 I have been offering Allergy Patch Testing to my Dermatology patients to help to figure out what may be causing flares of Contact Dermatitis, of Atopic Dermatitis (Eczema), or of Psoriasis. Let’s take a look at what’s involved in Allergy Patch Testing, because it can offer a cure from these itchy conditions and/or rashes.
First, many rashes felt to be Eczema or Psoriasis can in reality be In Cognito Contact Dermatitis. By the term “In Cognito Contact Dermatitis,” I mean that the patient is experiencing a type of allergic dermatitis due to a preservative, to a fragrance, or to a metal such as nickel with which the patient has come into contact. Other leading culprits can include components of latex, dyes, or mixing agents (emulsifiers) in cosmetics and toiletries. Sometimes the cause of the rash is as simple as an ingredient in the patient’s shampoo or laundry deterrent. So Allergy Patch Testing is a helpful way of evaluating the leading causes of contact rashes to try to ferret out what chemical may be implicated.
Allergy Patch Testing is to be distinguished from prick testing or RAST testing that may be available from Allergists, because they may be evaluating for respiratory or sinus allergies that involved a different set of culprit chemicals. Allergists may be more concerned with dietary components, with molds, danders, or mildews, whereas Allergy Patch Testing is centered around chemicals that your skin may come in contact with, such as chemicals that are in clothing or textiles, or cosmetics and toiletries. Some Allergists offer Allergy Patch Testing, whereas other Allergists will refer patients needing Allergy Patch Testing to Dermatologists.
Allergy Patch Testing involves having patches put under tape onto your back generally on a Monday of a week when you have time to return to get the patches removed and the sites evaluated for reactions, generally on the Wednesday and Friday of that same week. It’s generally a good idea to avoid antihistamines such as Benadryl, Zyrtec, and Allegra for 72 hours prior to the placement of the patches. We also prefer to have the patient avoid prednisone, an oral steroid, that week, because it could camouflage reactions in the testing. Furthermore, we prefer to avoid testing a patient when their rash is really active, because the patient will show up with false reactions.
In my own Memphis Dermatology practice, I am able to offer “Extended Allergy Patch Testing,” allowing me to evaluate for 86 or more different chemicals, in an attempt to avoid missing the patient’s allergies. This extended testing is sometimes called Dormer testing. The chemicals to which we test are updated every several years, as ongoing Dermatologic research uncovers new chemical culprits.
Once we identify, we can do an online search through the CARD database (Contact Allergen Referral Database) to help the patient to identify products that are free of that culprit chemical.