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Tests and diagnosis
By Mayo Clinic staffThere's no standard test used to confirm or rule out a food allergy. Your doctor will consider a number of things before making a diagnosis. The following may help determine if you're allergic to a food or if your symptoms are caused by something else:
- Description of your symptoms. Be prepared to tell your doctor a history of your symptoms — which foods, and how much, seem to cause problems — and whether you have a family history of food allergies or other allergies.
- Physical examination. A careful exam can identify or exclude other medical problems.
- Food diary. Your doctor may ask you to keep a food diary of your eating habits, symptoms and medications to pinpoint the problem.
- Skin test. A skin prick test can determine your reaction to a particular food. In this test, a small amount of the suspected food is placed on the skin of your forearm or back. Your skin is then pricked with a needle, to allow a tiny amount of the substance beneath your skin surface. If you're allergic to a particular substance being tested, you develop a raised bump or reaction. Keep in mind, a positive reaction to this test alone isn't enough to confirm a food allergy.
- Elimination diet. You may be asked to eliminate suspect foods for a week or two, and then add the food items back into your diet one at a time. This process can help link symptoms to specific foods. However, this isn't a foolproof method. Psychological factors as well as physical factors can come into play. For example, if you think you're sensitive to a food, a response could be triggered that may not be a true allergic one. If you've had a serve reaction to a food in the past, this method may not be safe.
- Blood test. A blood test can measure your immune system's response to particular foods by checking the amount of allergy-type antibodies in your bloodstream, known as immunoglobulin E (IgE) antibodies. For this test, a blood sample taken in your doctor's office is sent to a medical laboratory, where different foods can be tested. However, these blood tests aren't always accurate.
- Oral food challenge. During this test, done in the doctor's office, you'll be given small, but increasing amounts of the suspect food. If you don't have a reaction during this test, you may be able to include this food in your diet again.
References
- Burks W. Clinical manifestations of food allergy: An overview. http://www.uptodate.com/home/index.html. Accessed Nov. 11, 2010.
- Food allergy: An overview. National Institute of Allergy and Infectious Diseases. http://www.niaid.nih.gov/topics/foodAllergy/Documents/foodallergy.pdf. Accessed Nov. 11, 2010.
- Lack G. Food allergy. New England Journal of Medicine. 2008;359:1252.
- Atkins D. Food allergy: Diagnosis and management. Primary Care: Clinics in Office Practice. 2008;35:119.
- Hoffman A, et al. Pollen food allergy syndrome: Update on the allergens. Current Allergy and Asthma Reports. 2008;8:413.
- Chapman JA, et al. Food allergy: A practice parameter. Annals of Allergy, Asthma and Immunology. 2006;96:S1.
- Fleischer DM, et al. Oral food challenges in children with a diagnosis of food allergy. The Journal of Pediatrics. In press. Accessed Nov. 11, 2010.
- Fried AJ, et al. Anti-IgE in the treatment of allergic disorders in pediatrics. Current Opinion in Pediatrics. 2010;22:758.
- Scurlock AM, et al. An update on immunotherapy for food allergy. Current Opinion in Allergy and Clinical Immunology. 2010;10:587.
- Xiu-Min L. Complementary and alternative medicine in pediatric allergic disorders. Current Opinion in Allergy and Clinical Immunology 2009;9:161.
- Li X. Traditional Chinese herbal remedies for asthma and food allergy. Journal of Allergy and Clinical Immunology. 2007;120:25.
- Teuber SS, et al. Unproved diagnostic and therapeutic approaches to food allergy and intolerance. Current Opinion in Allergy and Clinical Immunology. 2003;3:217.
- Guidelines for the diagnosis and management of food allergy in the United States: Summary of the NIAID sponsored expert panel report. Bethesda, Md.: National Institute of Allergy and Infectious Diseases. http://www.niaid.nih.gov/topics/foodallergy/clinical/Pages/default.aspx. Accessed Dec. 13, 2010.
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