Diagnosis

To evaluate whether you have an allergy, your doctor may:

  • Ask detailed questions about signs and symptoms
  • Perform a physical exam
  • Have you keep a detailed diary of symptoms and possible triggers

If you have a food allergy, your doctor may:

  • Ask you to keep a detailed diary of the foods you eat
  • Have you eliminate a food from your diet (elimination diet) — and then have you eat the food in question again to see if it causes a reaction

Your doctor may also recommend one or both of the following tests. However, a positive reaction does not necessarily mean you are allergic to the substance.

  • Skin test. A doctor or nurse will prick your skin and expose you to small amounts of the proteins found in potential allergens. If you're allergic, you'll likely develop a raised bump (hive) at the test location on your skin.
  • Blood test. Specific IgE (sIgE) Blood Testing (commonly called RAST or ImmunoCAP testing) measures the amount of allergy-causing antibodies in your bloodstream, known as immunoglobulin E (IgE) antibodies. A blood sample is sent to a medical laboratory, where it can be tested for evidence of sensitivity to possible allergens.

If your doctor suspects your problems are caused by something other than an allergy, you may need other tests to identify — or rule out — other medical problems.