Oral Food Challenge Test
This is the gold standard for the diagnosis of food allergies. This test is conducted by an experienced allergist in a medical facility. The allergist will feed you the suspected food in measured doses, starting off in small amounts and then to larger amounts.
Elimination Diet
An allergist may ask you to eliminate specific foods in your diet for two to four weeks. During this time, the allergist may ask you to track your meals, monitor your symptoms, and reintroduce food products to observe any triggers. This test may be combined with the oral food challenge for more accurate results.
Blood Test
Blood tests measure the presence of antibodies that trigger food allergy symptoms. While blood test results are helpful in determining the presence of an allergy, it is not helpful in determining the severity of an allergy. 50-60% of blood tests may yield a “false positive” result. Meaning, the test may show a positive result even though the individual is not allergic to the food being tested.
Skin Prick Test
Skin prick tests are the least expensive, produce immediate results, and can be performed at the doctor’s office. During this test, the suspected food allergens are placed on the forearm or back using a plastic probe or needle. Then, the doctor scratches the skin to allow a tiny amount to enter the surface. A white bump surrounded by a small circle of itchy, red skin is likely to indicate that there is a food allergy present.
Like blood tests, 50-60% of skin prick test results may also yield a “false positive” result. Meaning, the test will show a positive result even though the individual is not allergic to the food being tested.
Factors That May Interfere with Test Results
- Prescription antihistamines -hydroxyzine
- OTC antihistamines – brand names include Claritin, Alavert, Benadryl, Zyrtec, and Allegra
- Tricyclic antidepressants such as nortriptyline and desipramine Heartburn medications such as cimetidine and ranitidine
- The asthma medication called omalizumab (Xolair) can disrupt test results for 6 months or longer even after one quits using it
Final Thoughts
Allergy tests, along with one’s medical history, may be an effective approach to confirming a food allergy. Before initiating a test, it is imperative that one discusses the various testing options with an experienced food allergist.
Helpful Website Searches
- Oral Food Challenge
- Food Elimination Diet
- Blood Tests
- Skin Prick Test
