Finger Prick Allergy Testing versus Skin Testing

People with allergies often ask the question: are all allergy tests the same? This article answers this question and discusses whether finger prick allergy testing is a good alternative to skin testing, usually only available at an allergist’s office.

What is Finger Prick Allergy Testing?

With finger prick allergy testing performed in your home, you receive a test kit with all the necessary components for pricking your finger. Once accomplished with a safety-type lancet, blood is collected in a small collection tube and sent to the laboratory by mail.

The laboratory checks for the presence of antibodies (proteins) in your blood. Antibodies are made by your immune system to fight infections, but they are also made if you are allergic to something in the environment. They come in 5 different types but only two are seen in allergic reactions: IgG and IgE antibodies.

They are very specific to a particular allergen. The laboratory can tell the difference between IgG and IgE antibodies and can say if you are allergic to a specific type of grass pollen or to something other than that. When IgE antibodies are activated, you can get hives, wheezing, and even anaphylaxis. IgG activation gives rise to an allergic response that is less dramatic, but often just as uncomfortable, particularly because it is more difficult to tell if you have an allergy to a substance.

Finger prick allergy testing allows hundreds of different allergy types to be tested with just a few drops of blood. Once the report returns, you’ll know which specific items you are allergic to and how prominent the antibodies were in the bloodstream.

What Is Skin Testing for Allergies?

Skin testing for allergies is done in the allergist’s office. The doctor creates a grid pattern on a large patch of your skin. Generally, a small needle is used to separately inject different allergens just under the skin. If you are allergic to the allergen and make IgE antibodies, there will be an area of raised, red skin around the site. This raised area is called a weal.

In some cases, a patch test can be done for delayed reactions. Patch testing instead places the allergen onto unbroken skin without using needles. Both injection and patch tests rely on IgE antibodies that cause histamine to be released by your immune cells, resulting in the visible reaction you can see. Generally, the larger the diameter of the weal, the more severe your allergy to the specific allergen you are exposed to.

Because skin testing requires a large patch of skin to adequately perform, only about 50 allergens can be tested for at once. Meaning you will be injected under the skin 50 times in only minutes! In addition, certain allergens you can test for with a finger prick allergy test that cannot be evaluated with skin prick testing.

Is Finger Prick Allergy Testing as Good as Testing at the Doctor’s Office?

While skin testing is an excellent way to demonstrate the presence of certain allergies, this type of testing has its limitations. Skin testing only detects IgE antibodies. It is limited in the number of allergens that can be evaluated at one time and it CAN’T test for:

• 1. IgG reactions
• 2. Food allergens
• 3. Any allergies you have if you’re taking antihistamines during the test
• 4. More than about 50 allergies at one time
• 5. Unusual allergies

Skin allergy testing also runs the risk of causing a serious allergic reaction during the examination. Because of the limitations, allergists often need to do both skin testing and blood testing for food allergies and any allergens the skin testing could not test at one time.

The Take-Home Message

Skin testing is often more accurate in indicating how strongly you’ll react to a given allergen, yet the doctor often has to choose just a selected number of allergens to test using this method. Finger prick allergy testing performed at home is not only safe, easy, convenient, and inexpensive, but it can detect hundreds of allergic responses to many different allergens at once.