You will be asked about your symptoms and medical history. A physical exam will be done. Food allergies are often diagnosed based on your own observations. It is a good idea to keep a diary of your symptoms. Note when the symptoms occur and what you have eaten.
Tests may include:
You may be asked to go on an elimination diet. This should be done under your doctor's care. You will not eat a suspected food. If your symptoms decrease or go away, your doctor may be able to make a diagnosis. If you eat the food and your symptoms come back, the diagnosis is confirmed. This is most often only done in cases of skin irritation or atopic dermatitis.
Scratch Skin Test
A diluted extract of the food will be placed on the skin of your forearm or back. The skin is scratched with a small pick or tiny needles. If there is swelling or redness, an allergic reaction may be present. The doctor will make the diagnosis based on the skin test and your history of symptoms. In rare cases, skin tests can have a severe allergic reaction. This test should only be used under the supervision of a physician or other trained medical personnel. Severe eczema may make this test hard to interpret.
RAST or ELISA Test
Blood tests (RAST or ELISA) may be ordered. These tests measure the level of food-specific IgE in the blood. IgE is a type of protein that the body produces when it is exposed to something to which it is allergic. The presence of IgE in the blood may indicate an allergy, but is not enough to make a diagnosis.
If you think you've eaten something to which you are allergic and you have difficulty breathing, then call for emergency medical services right away.
- Epinephrine —injected immediately in the event of a severe, life-threatening reaction (anaphylaxis)
- Antihistamine medication —to decrease swelling and itching
- Corticosteroid medication—for more severe swelling and itching
To reduce your chances of a food allergy reaction:
- Avoid eating or drinking substances to which you know you are allergic.
- Read the ingredient label on every food product that you eat.
- If you go to a restaurant, discuss your allergy with the food server. Ask about all ingredients.
- Learn the other names for all your allergens. This will help you recognize them on an ingredients list.
- If you have a severe, anaphylactic-type food allergy, ask your doctor if you should carry a dose of epinephrine with you.
- Consider wearing a medical alert bracelet to inform others of your allergy.
- Be aware that food may become contaminated by shared utensils, containers, and during preparation.
If you are diagnosed with a food allergy, follow your doctor's instructions. Consider seeing an allergist—a doctor who specializes in diagnosing and treating allergies.
This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.
Edits to original content made by Denver Health.
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American Academy of Allergy, Asthma & Immunology http://www.aaaai.org
Food Allergy Research & Education https://www.foodallergy.org
Allergy Asthma Information Association http://aaia.ca
Calgary Allergy Network http://www.calgaryallergy.ca
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Food allergy. National Institute of Allergy and Infectious Diseases website. Available at: https://www.niaid.nih.gov/diseases-conditions/food-allergy. Updated March 27, 2017. Accessed October 2, 2017.
Immunoglobulin E (IgE)-mediated food allergy. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T114561/Immunoglobulin-E-IgE-mediated-food-allergy . Updated July 19, 2017. Accessed October 2, 2017.
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