Evaluation and Food Diaries
The first step in diagnosing allergies is for the physician to perform a physical, taking note of allergy signs and symptoms as well as the times and places an allergic reaction took place. According to the Mayo Clinic, the doctor will typically ask the patient to keep a diary of all food and beverage intake. When the patient encounters a suspected food trigger, she will then alternate between abstaining from that suspected trigger and then ingesting a small amount of the trigger, noting any reactions that occur.
Skin Testing
Your physician may refer you to an allergist to have a skin test performed. In this test, small amounts of multiple common allergens are introduced to the patient through skin pricks; if the patient is allergic to the allergen protein, swelling or a hive will erupt on the site. The American Academy of Allergy, Asthma, and Immunology states that an allergic reaction will occur within 15 minutes and usually subsides within half an hour.
Blood Testing
When an allergen enters the bloodstream, the body produces antibodies in response. The allergist may perform a radioallergosorbent (RAST) blood test, where he introduces a suspected allergen into the bloodstream to measure the exact response of the immune system to a specific allergen. Both skin and blood tests should always be performed by an allergist, as in rare cases, a patient may experience a severe allergic reaction to the tests.
