What is allergy skin testing?
Allergy skin testing helps us figure out what may be causing your allergies. Doctors use two main types of allergy skin tests; the most common is called a skin prick test and the other is an intradermal test.
For a skin prick test, a small plastic pick is dipped into a substance to which you may be allergic and then is used to make a tiny prick into your skin. We then watch to see if the skin around the prick turns red and bumpy. If that happens, then it usually means that you are allergic to the substance. For children we use a ‘multi-test’ which allows us to conduct the screening test quicker and more comfortably. It allows us to test up to eight substances at a time. If your skin does not turn red and bumpy, then depending on if we think that you could still be allergic to the test substance, we may resort to an intradermal test.
For an intradermal test, a tiny amount of the substance is injected into your skin. Because more of the test substance gets into the skin, an intradermal test is slightly better at indicating a potential allergic substance. Since it is a stronger type of test, sometimes it can cause allergic reactions, so it is not done for some types of allergies, including food allergies.
What happens during skin allergy testing?
Some medications interfere with allergy tests. So, depending on which medications you are using, we may tell you to stop taking certain medicines (such as allergy medicines) up to one week before your allergy skin test. Please call us before your appointment to get more specific guidance on this.
The allergy skin tests, pricks or injections, are done most commonly on your arms. Sometimes they are done on the upper part of your back.
Although this is not painful, small children might find it upsetting. If you are allergic to any of the substances, itchy red bumps usually show up in 15 to 20 minutes. The bumps and itchiness go away within an hour or so.