Patient education: Allergy skin testing (The Basics)

What is allergy skin testing? — 

This is a way to help find out what a person is allergic to.

Why do I need allergy skin testing? — 

Your doctor might recommend it if you have symptoms that seem to be caused by an allergy. The table shows common types of allergies and their symptoms (table 1).

If you know exactly what is causing your allergies, you can avoid those things and choose the best treatment.

How do I prepare for allergy skin testing? — 

Your doctor might tell you to stop taking certain medicines (such as allergy medicines) for up to 1 week before you get the test. This is because some medicines can block the skin test reaction, making the results appear normal even if you actually do have an allergy.

What happens during skin allergy testing? — 

There are 2 main types of allergy skin tests. The most common is called a skin prick test. The doctor puts a drop of the substance you might be allergic to on your skin and makes a tiny prick through the drop into your skin. If you are allergic to any of the substances, itchy red bumps usually show up within 15 to 20 minutes. The bumps go away within an hour or so.

If your skin does not turn red and bumpy during the skin prick test, your doctor might still suspect that you are allergic to the substance. They might inject a tiny amount of it under your skin. This is called an "intradermal" test. It is slightly better at showing an allergy because more of the substance gets into your skin. Because this is a stronger test, it can sometimes cause allergic reactions, and it is not done for some types of allergies, such as food allergies.

The pricks or injections are done on the arms and sometimes on the upper part of the back. They are not painful, but small children might find it upsetting. You might get tested for a few different substances at the same time.

More on this topic

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Patient education: Environmental allergies in children (The Basics)
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Patient education: Allergic bronchopulmonary aspergillosis (The Basics)
Patient education: Anaphylaxis (The Basics)

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