Allergy Blood Tests: About These Tests

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What are they?

Allergy blood tests look for substances in the blood (antibodies) that the body makes in response to allergens. Allergens are things that the body is allergic to.

There are several types of allergy blood tests including:

  • Enzyme-linked immunosorbent assay (ELISA, EIA).
  • Radioallergosorbent testing (RAST).
  • Immunoassay capture test (ImmunoCAP, UniCAP, or Pharmacia CAP).
  • Fluoro-allergosorbent testing (FAST).
  • Multiple antigen simultaneous testing (MAST).

Why are these tests done?

Allergy blood tests are done to find out what things you are allergic to.

What happens during these tests?

The health professional taking a sample of your blood will:

  • Wrap an elastic band around your upper arm. This makes the veins below the band larger so it is easier to put a needle into the vein.
  • Clean the needle site with alcohol.
  • Put the needle into the vein.
  • Attach a tube to the needle to fill it with blood.
  • Remove the band from your arm when enough blood is collected.
  • Put a gauze pad or cotton ball over the needle site as the needle is removed.
  • Put pressure on the site and then put on a bandage.

What else should you know about these tests?

The results of allergy blood tests are usually available in about 7 days.

Where can you learn more?

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