Food Allergy Testing

A food allergy happens when your immune system - your body's defense against germs - overreacts to a certain food as if it was harmful. If you have symptoms after eating certain foods, food allergy testing can help find out if your symptoms are caused by an allergic reaction to those foods. And it's important to find out because allergic reactions to food can be serious.

Most food allergy symptoms are mild and include skin rashes and abdominal (belly) pain. But sometimes, symptoms quickly develop into a life-threatening allergic reaction called anaphylaxis, or anaphylactic shock. Anaphylaxis is a medical emergency that may affect your whole body, including your breathing.

And there's no way to predict when an allergic reaction may change from mild to serious. If you have a food allergy, eating even tiny amounts of a certain food or ingredient can quickly trigger your immune system to react. Most food allergies are caused by: Milk; Eggs; Peanuts; Tree nuts (including almonds, walnuts, pecans, and cashews); Soy; Wheat; Fish; Shellfish; Food allergies are more common in children than adults.

Most children will grow out of allergies to milk, egg, soy, and wheat. But if a food allergy begins in adulthood, it's likely to continue through life. If you or your child has symptoms that could be from a food allergy, your or your child's health care provider will probably refer you to an allergist for testing.

An allergist is a doctor who specializes in diagnosing and treating allergies and asthma. The allergist will pick the type of food allergy test that's right for you or your child. Tests include skin tests, blood tests, and a test where you eat small amounts of a suspected food while a provider watches for signs of allergy.

Why this test is done

You or your child may need food allergy testing if either of you:

• Have symptoms within minutes to hours after exposure to certain foods. Symptoms may affect your digestion, skin, and/or breathing, and may include:
• Nausea and vomiting
• Stomach pain
• Diarrhea
• Tingling in the mouth
• Skin reactions, such as hives or itching.
• Red, itchy skin or a rash
• Coughing
• Stuffy, itchy, or runny nose
• Have had symptoms of anaphylaxis. Symptoms of this life-threatening reaction may appear within minutes to hours after exposure to certain foods. Symptoms include:
• Trouble breathing
• Dizziness
• Fainting
• Swelling of the tongue, lips, and/or throat
• Rapid heart rate
• Cold, clammy, skin that may appear grayish, bluish, or pale

If someone has symptoms of anaphylaxis, call 911 to get medical help right away.

You may also have food allergy testing if you or your child has been diagnosed with eosinophilic esophagitis (EoE). Testing is done to find out which foods may make this condition worse.

Your child's provider may recommend food allergy testing if your infant or child has been diagnosed with:

• Moderate to severe eczema
• Enterocolitis, inflammation of the colon and small intestine
• Enteropathy, a disease of the intestine
• Allergic proctocolitis, a disorder that involves streaks of blood and mucus in stool (poop)

How to prepare

If you are having any type of allergy test, you may need to stop taking certain medicines and/or supplements before the test. Your provider will let you know what to avoid and for how long. Don't stop taking any medicines unless your provider tells you to.

Your test may require other preparation, so be sure to follow all your provider's instructions for getting ready.

Sample type

Blood

Other names for this test

IgE test, sIgE test, allergen-specific IgE in serum, skin prick test (SPT), oral challenge test