Allergy Skin Test

An allergy is an overreaction by your immune system to something that doesn't bother most people. An allergy skin test helps find out what is causing your allergic reaction by exposing your skin to allergy-causing substances known as allergens. Your immune system is your body's defense system.

It usually fights germs. But when you have an allergy, your immune system sees a harmless substance, like dust or pollen, as a threat. Your immune system responds to this 'threat' and causes an allergic reaction.

Symptoms of an allergic reaction can range from sneezing and a stuffy nose to a life-threatening condition known as anaphylactic shock. During an allergy skin test, your health care provider will expose your skin to a suspected allergen to see if you have an allergic reaction. Substances that could cause an allergic reaction can include: Pollen; Dust mites; Molds; Pet dander; Food; Insect bites and stings; Medicines; Household chemicals; The overreaction an allergy causes is also known as a hypersensitivity of your immune system.

There are four main types of overreactions, known as Type 1 through Type IV hypersensitivities. Type 1 hypersensitivity causes some of the most common allergies. These include dust mites, pollens, foods, and animal dander.

Other types of hypersensitivities cause different immune system overreactions. These range from mild skin rashes to serious autoimmune disorders. An allergy skin test usually checks for allergies caused by Type 1 hypersensitivity.

The test looks for reactions to specific allergens that are placed on the skin.

Why this test is done

Your provider may order allergy testing if you have symptoms of an allergy. These include:

• Stuffy or runny nose
• Sneezing
• Itchy, watery eyes
• Hives, a rash with raised red patches
• Diarrhea
• Vomiting
• Shortness of breath
• Coughing
• Wheezing

How to prepare

You may need to stop taking certain medicines before the test. These could include antihistamines and certain antidepressants. Your provider will tell you which medicines to avoid before your test and for how long.

They may also ask about any products you use on your skin and if you are normally around animals.

If you are having a patch test, your provider may want you to avoid heavy sun exposure and tanning for at least two weeks before the test.

If your child is being tested, the provider may apply a numbing cream to their skin before the test.

Other names for this test

type 1 hypersensitivity skin test, hypersensitivity test allergy scratch test, allergy patch test, intradermal test, prick test, puncture test