Allergy patch testing

Sometimes when a skin rash develops, it can be difficult to find the cause. Allergy patch testing helps pinpoint whether a specific substance is responsible. The test involves placing small amounts of chemicals on patches made of hypoallergenic adhesive paper, which are then taped to your back or upper arm.

Patch testing is typically done by dermatologists, who can determine whether your skin condition is due to an allergic reaction or another issue. At Penn Dermatology, we use a targeted patch testing approach to thoroughly identify substances causing allergic contact dermatitis.

Most adults and children can safely have allergy patch testing. You may be a good candidate if you:

• Haven’t had a severe allergic reaction in the past that could raise your risk during testing.
• Are able to temporarily stop certain medicines that might affect your results, like antihistamines, steroids, some antidepressants, or heartburn medications.
• Have a healthy patch of skin, usually on your back, where the test can be done.

After your test, the skin where the patches were placed may itch or burn. This is a common reaction. Over-the-counter antihistamines can help ease discomfort. If you had a positive reaction, the area might stay red, swollen, and itchy for a while. You may also get blisters or skin discoloration, which can take time to go away. If you develop a new reaction after your last appointment, take a picture and call your provider for guidance.

Patch testing is a low-risk way to identify delayed allergic reactions, but there are some possible side effects. These include mild redness, itching, or burning at the test site, which usually clears up in a few days. You might also notice some temporary changes in skin color where the patches were applied.

Less commonly, patch testing can cause flare-ups of skin conditions like eczema or, in rare cases, small blisters or even new allergies to the tested materials can result. Severe allergic reactions to patch tests are very rare but can happen. Your provider will review your medical history to decide if patch testing is right for you.

When you have an uncomfortable rash that isn’t getting better, you want a care provider who can not only relieve your symptoms but also find the cause. Penn Dermatology allergy experts use a targeted patch testing technique to quickly identify the substance causing your reaction. Unlike standard pre-packaged tests, our customized approach increases the chances of pinpointing the specific allergen and finding an effective treatment.

The specialists at Penn Dermatology are among the nation’s leading experts in treating skin conditions. They’re frequently honored by publications such as Philadelphia Magazine’s Top Docs™, Best Doctors in America, and America’s Top Doctors for their outstanding patient care and expertise in treating conditions like allergic contact dermatitis, eczema, and other complex rashes.