Tests and diagnosis

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

Ask detailed questions about signs and symptoms

1. Perform a physical exam
2. Have you keep a detailed diary of symptoms and possible triggers
3. If you have a food allergy, your doctor may:
4. 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 reactionYour doctor may also recommend one or both of the following tests:

Skin test. Your skin is pricked and exposed 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. Allergy specialists usually are best equipped to perform and interpret allergy skin tests.

Blood test. A blood test that's sometimes called the radioallergosorbent test (RAST) can measure your immune system's response to a specific allergen by measuring 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.