Diagnosis

To evaluate whether you have an allergy, your doctor will likely:

• 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 will likely:

• Ask you to keep a detailed diary of the foods you eat
• Ask if you've stopped eating the suspected food during the allergy evaluation

Your doctor might also recommend one or both of the following tests. However, be aware that these allergy tests can be falsely positive or falsely negative.

• 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 radioallergosorbent test (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, other tests might help identify — or rule out — other medical problems.