Allergy Testing

In order to find out exactly what your child is allergic to, your doctor may order allergy testing. Allergy testing can either be a skin or a blood test. These tests can identify what substance, or allergen, may trigger an allergic response.

  • Skin Test

      A skin prick test is when a small drop of a possible allergen is put on the skin. The skin under each drop is then pricked or scratched with a small needle to let it get into the skin. 

      If your child is allergic to that allergen, the spot will become red, bumpy, and itchy. Your doctor will be able to tell you what your child is allergic to based on the skin test the same day.

      Preparing for Skin Tests

      Your child should stop taking any antihistamine medications, like cetirizine (Zyrtec®), fexofenadine (Allegra®) and loratadine (Claritin®), for several days before an allergy skin test. Antihistamines can stay in the body and interfere with skin test results by suppressing reactions. Talk to your child’s doctor about what medications to stop and when to stop them prior to allergy testing.

      What Does the Skin Test Feel Like?

      The skin prick test feels like small pricks or pinches. If your child has an allergic reaction from any of the skin tests, he may have some itching, tenderness, and swelling where the test was done. Cool cloths or a nonprescription steroid cream, like Benadryl, can be used to help with itching and swelling after the test.

  • Blood Test

      Allergy blood tests look for antibodies in the blood. Antibodies are things that signal an allergic reaction. 

      How Allergy Blood Tests are Done

      The health professional drawing your child's blood will:

      - Wrap a tight rubber band around your child's arm. This makes the veins below the band larger so it is easier to find a good vein.
      - Clean the spot with alcohol.
      - Poke the needle through the skin and into the vein. More than one poke may be needed.
      - Attach a tube to fill it with blood.
      - Remove the band from your child's arm when enough blood is collected.
      - Apply a gauze pad or cotton ball over the spot as the needle is removed.
      - Apply pressure to the spot and then a bandage.

      The blood sample will be sent to a lab to determine whether antibodies to any of the allergens being tested are present. If specific antibodies are found, it may mean your child is allergic to a certain allergen. Your doctor should get the results within a few days.

      How it Feels

      Your child may feel nothing at all from the needle puncture, or he may feel a brief sting or pinch as the needle goes through the skin. Some people feel a stinging pain while the needle is in the vein. Many people do not feel any pain or have only minor discomfort after the needle is positioned in the vein.