How do doctors test for food allergies? – Debra Doctors often use a combination of skin testing and blood testing to diagnose a food allergy. One common skin test is a scratch test. For this test, a doctor or nurse will scratch the skin with a tiny bit of liquid extract of an allergen (such as pollen or food). Allergists usually do skin tests on a person's forearm or back. The allergist then waits 15 minutes or so to see if reddish, raised spots (called wheals) form, indicating an allergy. If the doctor thinks someone might be allergic to more than one thing — or if it's not clear what's triggering a person's allergy — the allergist will probably skin test for several different allergens at the same time. When a skin test shows up as positive with a certain food, that only means a person might be allergic to that food. In these cases, doctors may want to do additional testing. To diagnose a food allergy for certain, an allergist might do a blood test in addition to skin testing. This involves taking a small blood sample to send to a laboratory for analysis. The lab checks the blood for IgE antibodies to specific foods. If enough IgE antibodies to a particular food are in the blood, it's very likely that the person is allergic to it. If the results of the skin and blood tests are still unclear, though, an allergist might do something called a food challenge. During this test, the person is given gradually increasing amounts of the potential food allergen to eat while the doctor watches for symptoms. Skin tests may itch for a while. If your child undergoes one, the allergist might give you an antihistamine or steroid cream for your child to use after the test to lessen the itching. Back to Articles Related Articles Allergies Your eyes itch, your nose is running, you're sneezing, and you're covered in hives. The enemy known as allergies has struck again. Read More Help With Hives Hives are red, itchy blotches that can appear because of an allergic reaction. 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Read More Food Allergies and Food Sensitivities Find more than 30 articles in English and Spanish about all aspects of food allergies in children. Read More If My Child Has Food Allergies, What Should I Look for When Reading Food Labels? Food labels can help you spot allergens your child must avoid. Find out more. Read More What's the Difference Between a Food Allergy and a Food Intolerance? Food allergies and food intolerances, like lactose intolerance, are not the same. Find out more. Read More Going to School With Food Allergies With preparation and education, a child with a food allergy can stay safe at school. Read More Food Allergies Food allergies can cause serious and even deadly reactions in kids, so it's important to know how to feed a child with food allergies and to prevent reactions. Read More What Is Skin Testing for Allergies? A scratch or skin prick test is a common way doctors find out more about a person's allergies. Read More How Do Doctors Test for Allergies? Find out what the experts have to say. Read More All About Allergies Millions of Americans, including many kids, have an allergy. Find out how allergies are diagnosed and how to keep them under control. Read More Milk Allergy Milk allergy can cause serious reactions. Find out how to keep kids safe. Read More Serious Allergic Reactions (Anaphylaxis) Kids with severe allergies can be at risk for a sudden, serious allergic reaction called anaphylaxis. The good news is that when treated properly, anaphylaxis can be managed. Read More Fish Allergy Fish allergy can cause a serious reaction. Find out how to keep kids safe. Read More Allergy Shots Many kids battle allergies year-round, and some can't control their symptoms with medications. For them, allergy shots (or allergen immunotherapy) can help. Read More Nut and Peanut Allergy If your child is allergic to nuts or peanuts, it's essential to learn what foods might contain them and how to avoid them. Read More Milk Allergy in Infants Almost all infants are fussy at times. But some are very fussy because they have an allergy to the protein in cow's milk, which is the basis for most commercial baby formulas. Read More Egg Allergy Helping your child manage an egg allergy means reading food labels carefully, being aware of what he or she eats, and carrying the right medicines in case of an allergic reaction. Read More Hives (Urticaria) Has your child broken out in welts? It could be a case of the hives. Learn how to soothe itchy bumps and help your child feel better. Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.