Allergy Diagnosis

How is an accurate diagnosis made?

To make a diagnosis, allergists ask detailed questions about your medical history and your symptoms. Be prepared to answer questions about:

  • What and how much you ate

  • How long it took for symptoms to develop

  • What symptoms you experienced and how long they lasted

After taking your history, your allergist may order skin tests and/or blood tests, which indicates whether food-specific immunoglobulin E (IgE) antibodies are present in your body:

  • With a skin-prick test, a liquid containing a tiny amount of the food allergen is placed on the skin of your arm or back. Your skin is pricked with a small, sterile probe, allowing the liquid to seep under the skin. The test, which isn’t painful but can be uncomfortable, is considered positive if a wheal (resembling the bump from a mosquito bite) develops.

  • Blood tests, which are a bit less exact than skin tests, measure the amount of IgE antibody to the specific food(s) being tested. Results are typically available in about a week and are reported as a numerical value.

Your allergist will use the results of these tests in making a diagnosis. A positive result does not necessarily indicate that there is an allergy, though a negative result is useful in ruling one out.  Skin tests alone are not considered enough to diagnose a food allergy.