WHAT IS PATCH TESTING?
Patch testing is a skin test done in your dermatologist’s office which attempts to find the allergen or substance which may be the cause of your rash. Common agents in causing this reaction include jewelry, make-up, topical products, detergent, perfumes, latex rubber and many other common things you come in contact with on a daily basis.
WHAT IS ALLERGIC CONTACT DERMATITIS?
Allergic contact dermatitis is a condition in which you develop areas of inflammation on your skin (called dermatitis) when your skin reacts against a specific substance. These allergens do not cause rashes in most people but for some, their immune system will react when these substances come in contact with the skin. Common symptoms in contact dermatitis may include: scaly itchy rash, hives or blisters.
These symptoms can last for weeks, and can usually be treated at home through medications and topical creams. However, the best treatment is identification and avoidance of these substances as much as possible. A patch test may help in identifying the agents you need to avoid in order to reduce your symptoms.
IS PATCH TESTING PAINFUL?
Patch testing is a simple and painless process. It does not require the use of any needles or injections. The reaction which may be provoked can result in itchy areas on the back.
HOW LONG DOES PATCH TESTING TAKE?
Patch testing is a week long process. On your first scheduled visit, your dermatologist will apply several small pieces of tape with various potential chemicals to the skin on your back. These chemicals are left on for 48 hours. You need to avoid direct sun, excessive sweating and showering the area during this time. After 48 hours, you will return to the office to remove the tape for an initial reading. This reading is necessary to observe any reactions. The doctor will perform an evaluation after another 48 hours, which will determine the results. A typical schedule for testing is to come in on a Monday (to apply patches), Wednesday (to remove patches) and Friday (to read results). There are even some late reactions on the following Monday which may be relevant.
WHAT TO DO BEFORE THE PATCH TEST.
Before undergoing patch testing, you are recommended to stop using topical corticosteroids in the area to be tested, avoid oral antihistamines and steroids, and not expose the test area to the sun for at least three weeks. These factors may invalidate test results.
When reading the results, each spot will be classified on a scale from negative (meaning no reaction) to extreme reaction (meaning positive results for substance). Strong results may cause blisters or ulcers on the skin, which can be treated once the test is complete.
Once the allergens or allergic substances have been elucidated, you will be provided with specific information on your individual triggers and how to prevent contact. You will be given education specifically on how to edit and review your everyday exposures in order to AVOID these offending substances and where to go to choose products which are void of these substances.