What To Expect If Your Allergist Recommends Patch Testing

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In some people, the immune system sees harmless substances, such as pollen and pet hair, as foreign invaders that must be attacked immediately. This triggers the production of antibodies, setting off a chain reaction of allergy symptoms. Allergists often use skin testing to determine which substances are causing your allergy symptoms; patch testing is a specific type of skin test that involves placing patches on the skin. Each patch has a specific allergen on it, so the purpose of the test is to determine if any of the allergens trigger your symptoms. If your doctor recommends patch testing, here is what you can expect from the process.

Allergens Tested

This process typically tests for allergies to common substances such as hair dyes, artificial fragrances, metals, and preservatives; however, the allergens used in the testing process are selected especially for you based on your symptoms and medical history. During the patch test, your doctor applies an extract of each potential allergen to a single patch; all of the patches are labeled and placed on your skin. The labels make it easy to identify which patches cause allergy symptoms and which ones do not.

Patch Placement

The patches will be placed on your back or your arm, so you must be careful when engaging in activities such as yard work, sports, or anything else that requires a lot of twisting or movement. In the days leading up to your patch test, avoid exposing the test area to sunlight, as UV radiation can affect how your immune system responds to the presence of an allergen. You should also refrain from applying lotions, ointments, and creams to the test site on the day of your appointment.

Caring for the Patches

In addition to avoiding excessive movement, you must be careful not to get the patches wet. If possible, avoid any activities that produce an excessive amount of sweat, such as mowing the lawn on a hot day, hauling heavy objects, or doing an intense workout. When it's time to shower, cover the patches with waterproof material to ensure they are not damaged by water. Several medical supply companies make shower covers and other products to help keep casts dry; one of these products may be suitable for covering up your test patches.


Some people have a reaction right away, while others have delayed reactions that take a day or more to develop. If you have a reaction to one of the allergens, you can expect to feel some itching. When the patch is removed, there may also be some redness and irritation at the site. Your allergist may recommend applying a steroid cream to the skin to relieve the itching and speed up the amount of time it takes the skin reaction to disappear. For best results, your doctor should check the test site at least twice during the process, as a delayed reaction may not show up for as long as a week after the patches are applied.

Patch testing is especially helpful for identifying allergies to substances that cause a delayed reaction, so this process is often recommended by allergists. If your doctor suggests this type of test, look for patch test services in your area. An experienced professional can conduct the patch test and help you get to the bottom of your allergy symptoms.

For more information, contact a company like Allergy Asthma Specialists.