Relief Allergy & Sinus Institute

Patch testing (chemical allergy)

Allergy testing can take many forms including scratching or poking just under your skin with a needle, blood tests, oral ingestion (swallow) tests and patch testing. You may need a combination of tests depending upon your symptoms.

Our patch testing technique is specific for diagnosing allergic contact dermatitis and doesn’t involve any needles – just patches on your back. Allergic contact dermatitis is due to an overreaction of your immune system to a substance touching your skin, called an allergen. Your body senses the allergen as a foreign invader (like bacteria or viruses) and springs into action by producing antibodies to that allergen.

Symptoms of Allergic Contact Dermatitis:
  • Red rash with bumps and sometimes blisters
  • Itching which may be severe
  • Dry, scaly skin which may crack
  • Skin swelling, tenderness and burning
Causes of Allergic Contact Dermatitis:

Allergic contact dermatitis is caused by an overreaction of your immune system to an allergen when it touches your skin. Your body produces antibodies to that allergen. Then when you come into contact with the substance again, the antibodies grab it and cause your immune cells to release histamine and other chemicals. Allergic causes include poison ivy, oak, or sumac; metals like nickel; hair dyes or straighteners; citrus fruits; latex rubber; and some medications applied to your skin.

How does Patch Testing Work?

During patch testing, your doctor will apply suspected allergens to patches that are placed on the skin of your back. The patches are typically placed on the back, left on for two days and then removed. The area of skin that was tested will be evaluated by your allergy provider two to four days after the patches are removed. Your doctor will then look for your skin reactions to various allergens. A positive test may show anything from just a small amount of redness to a larger allergic area with severe itching.

What to Expect During Patch Testing?

Our specialists will advise you on everything you need to know before and after your patch testing. A few key points are:

  • You may notice itching or burning if you have a positive test, but you must try not to scratch the area with the patches
  • No swimming with patches, only light exercise without much sweating, and avoid heat and sunlight as much as you can
  • Showering may be possible if your doctor uses a water-resistant cover over the patches. Never scrub the testing skin area until you see your doctor after the test.
  • Patch testing does not test for immediate allergic reactions to foods or other allergens, just a delayed type of allergy that takes several hours to a couple days to react
  • Patch testing does not test for allergies to pollen, mold, pets or food. It also can’t test for causes of hives (urticaria).

If you would like to learn more about how Relief Allergy & Sinus Institute can use patch testing to diagnose and help get your allergic contact dermatitis under control, request an appointment today online or call (630) 513-1691.