Allergy Testing

What is allergy skin testing? — Allergy skin testing is testing that helps your doctor figure out what you are allergic to. Doctors use 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. He or she then watches your skin to see if the skin around the prick turns red and bumpy. If that happens, it usually means you are allergic to the substance.

If your skin does NOT turn red and bumpy, your doctor might still think you could be allergic to the substance. If that happens, he or she might inject a tiny amount of the substance under your skin. This is called an “intradermal” test. Intradermal tests are slightly better at showing an allergy because more of the test substance gets into the skin. Because this is a stronger type of test, it can sometimes cause allergic reactions, and it is not done for some types of allergies, such as food allergies.

Why do I need allergy skin testing? — Your doctor might recommend allergy skin testing 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 the substances and choose the best treatment.

What happens during skin allergy testing? — Your doctor might tell you to stop taking certain medicines (such as allergy medicines) for up to 1 week before you get an allergy skin test.

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

If you are allergic to any of the substances, itchy red bumps usually show up in 15 to 20 minutes. The bumps go away within an hour or so.