Food Allergy Testing
Reviewed
Also called: IgE test, sIgE test, allergen-specific IgE in serum, food allergy blood test
If you or your child has symptoms after eating certain foods, food allergy testing can help find out if your symptoms are caused by an allergic reaction to those foods.
Specimen: Blood
Urgent safety information
Anaphylaxis is a life-threatening allergic reaction that 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. An autoinjector is a small device that you use to inject an emergency allergy medicine, called epinephrine. If you need to use the device, it's still very important to get medical help right away even if you feel better.
Emergency numbers on this page are for the United States. Outside the US, call your local emergency number.
Why this test may be ordered
- To help diagnose food allergies in people who have symptoms after eating certain foods.
- To help distinguish between a food allergy and a food intolerance or sensitivity.
- To see if allergies have gone away over time.
Preparation and collection
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.
A provider, often an allergist, will ask about your or your child's symptoms, family health history, and medical history, including other allergies. There are many types of allergy tests, and they have different risks. So, ask your provider which tests are best for you or your child.
A skin prick test can cause itchy or irritated skin. The test is generally safe, but a severe reaction is possible. A blood test has very little risk. An oral challenge test can cause a severe allergic reaction. That's why this test is done with close supervision by an allergist who can treat you if there is an emergency. An elimination diet may cause a serious allergic reaction. Ask your allergist what to do if you develop symptoms. A food elimination diet may not be safe for someone who has had a serious allergic reaction to food in the past.
Understanding results
A food challenge test is the only food allergy test that can confirm a diagnosis of a food allergy.
- Allergy diagnosed: If the allergist diagnoses a food allergy, the treatment is to avoid the foods that trigger your symptoms. Limitation: There is no cure for food allergies. Next step: In case you or your child has a severe allergic reaction, your allergist may prescribe an autoinjector.
- IgE blood test result: If you had a blood test, your results may show the amount of IgE in your blood. Limitation: This amount can't confirm a food allergy or tell you how serious an allergy may be. Next step: To confirm if you have an allergy, your provider will have to use the results from other tests.
- This test cannot confirm a food allergy on its own.
- The level of IgE does not predict how severe an allergic reaction may be.
- False positives (high IgE without allergy) and false negatives (normal IgE despite allergy) can occur.
What to do next
If you have questions about test results and/or how to manage allergic reactions, talk with your allergist.
- What do my test results mean?
- Do I need additional tests?
- How should I prepare for an oral food challenge if needed?
- What foods should I avoid based on these results?
- Do I need to carry an epinephrine autoinjector?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.