what does a blood test of allergies show?
Types of Allergy Blood Tests. Allergy blood tests detect and measure the amount of allergen-specific antibodies in your blood. When you come into contact with an allergy trigger, known as an allergen, your body makes antibodies against it.llergy blood testing is recommended if you: 1  Are using a medicine known to interfere with test results and cannot stop taking it for a few days. 2  This would include antihistamines, steroids, and certain antidepressants.