Prick skin testing, also known as scratch testing, is one type of food allergy test. A small disposable prick device applies the allergy extract to the skin by scratching or pricking the skin. A hive or raised bump may occur at the site of the prick test. Each test site will be measured and compared to a positive and negative control allowing for specific allergies of the patient to be identified. Prick testing may be applied to the forearms or the back depending upon the age of the patient, the number of tests ordered, and the condition of the skin. Results occur, typically between 10-20 minutes.
Another test for foods, if indicated, is an oral food challenge which is performed in the medically safe environment of an allergist office. The patient generally brings a single food item into the office and it is given under the supervision of the doctor. Patients are monitored during this time for any signs of a reaction.
Another type of testing known as a RAST or Immunocap testing involves examining specific IgE in the blood. The benefit of this test is it involves a single needle stick and results are typically obtained within a few days.
Sometimes, it’s easy to identify a food that you are likely allergic to, such as if you break out in hives or a rash after eating peanuts or shellfish. Other times, the source of your allergic reaction may not be so exact. In that case, an allergist will examine your medical history, ask about your family history of allergies, and ask you relevant questions including: