About the Test
Purpose of the test
The purpose of an at-home food allergy test is to help assess whether you might have an immune reaction to a certain food or ingredient. By analyzing your blood, tests can detect signs that your immune system may react to foods that most people can eat without any problem.
Testing is one component of diagnosing a food allergy, but a blood test alone cannot prove whether you have a food allergy. A blood test, including an at-home test, must be interpreted in the context of your symptoms and history of reactions when eating a specific food.
Diagnosing food allergies is important because allergic reactions can cause burdensome symptoms and, in some cases, can even be life-threatening. If a food allergy is suspected, there are a number of tests that have to be completed in consultation with a health care provider including a skin prick test and an oral food challenge.
Another purpose of food allergy testing can be to monitor changes in an allergy response over time. Many children with food allergies stop being allergic as they enter adolescence and adulthood. Repeat blood testing is one potential method of trying to determine if they remain allergic to a certain food.
To learn more about tests used to diagnose and monitor food allergies, see our Food Allergy Testing page.
How are food allergies different from food sensitivities?
Food allergies are distinct from food sensitivities because food allergies involve a reaction driven by the immune system.
Food sensitivities or intolerances are a type of negative reaction to a food, but they are not caused by an immune response. Instead, these reactions may be caused by an inability to digest or properly metabolize an ingredient. Examples of food sensitivities include lactose intolerance or hypersensitivity to caffeine.
Symptoms of food allergies and sensitivities can be similar in some cases, but food allergies tend to be more serious and carry a higher risk of severe or life-threatening symptoms if not managed properly. Allergies are also more likely to be triggered by exposure to even tiny amounts of a particular type of food.
Because food allergy tests evaluate indicators of immune response, they do not identify food sensitivities.
What does the test measure?
At-home food allergy tests use a blood sample to measure the level of immunoglobulin E (IgE) related to one or more types of food. Different types of immunoglobulin E are produced by the immune system in response to particular allergens. For this reason, allergy tests usually measure levels of allergen-specific IgE, which is sometimes abbreviated sIgE.
While it is possible to check the levels of many types of sIgE in one blood sample, there is no single test that can check for all food allergies. In fact, most experts recommend against blood tests, including at-home tests, that look for long lists of potential allergens because of the potential for misleading test results that show elevated IgE when no true allergy exists.
Can at-home food allergy tests measure things other than immunoglobulin E levels?
There is no evidence to support the benefit of food allergy testing that measures things other than IgE. Although many such at-home tests are available, experts and leading medical organizations recommend against these tests because they have not been shown to assist in the identification of a food allergy.
For example, tests that measure immunoglobulin G (IgG) or IgG4 have not been proven or validated as methods of detecting allergic reactions to foods. Tests of hair samples are also unvalidated and not recommended by experts.
Because they can deliver misleading results, these unproven tests may cause unnecessary avoidance of foods or lead to potentially dangerous exposure to a food that the test did not detect as an allergen. Unvalidated tests may also delay more appropriate testing and diagnosis of food allergies.
When should I get an at-home food allergy test?
In general, testing for food allergies should only be done when you have had symptoms that could have been caused by an allergic reaction. Possible symptoms include the following health changes that occur after eating:
- Itching, red welts on the skin, or skin that is red and warm
- Nausea and/or vomiting
- Difficulty breathing
- Abdominal pain, diarrhea, and/or bloody stool
- Swelling in your face or throat
- Feeling like you may faint
If you experience any of these symptoms, you should contact your doctor. The doctor will review your symptoms and what you ate to determine if the cause could be a food allergy. They may ask if you have had any of these types of symptoms before. The most common food allergies are from peanuts, tree nuts, and seafood. Normally, the type of food allergy testing is determined based on your unique situation, and testing only looks for a limited number of suspected allergens.
While food allergy blood tests are largely used for diagnosis, they can also be used to monitor an allergy over time. There is no cure for a food allergy, but some people, especially children, outgrow allergies as they get older. Repeated blood testing may help determine if someone is still allergic to a certain food.
Allergy testing is tailored to your individual circumstances, so it is best to talk with your doctor or an allergist to determine whether at-home food allergy testing is appropriate in your case.
Benefits and Downsides of At-Home Food Allergy Testing
When deciding whether to take any medical test, it’s important to consider the potential benefits and downsides. Knowing the pros and cons of at-home food allergy testing can help you determine whether it is right for you.
Some of the main possible benefits of at-home food allergy testing include:
- Simple test process: Individual test kits include all the necessary instructions and materials for you to properly prepare your sample.
- Fingerstick blood sample: Instead of a typical blood draw from a vein in your arm, at-home tests use a sample of dried blood that you obtain by pricking your fingertip with a tiny needle.
- Convenience: With at-home sample collection, you can take the test according to your own schedule and without having to make an appointment or go to a medical office.
- Clear pricing: Even though you may have to pay for the full cost of testing, the price is normally displayed clearly and without hidden or extra costs.
- No allergen exposure: A benefit of blood testing for food allergies is that there is no actual exposure to possible allergens, eliminating the risk of an unwanted reaction during testing.
A few of the potential downsides to at-home food allergy testing include:
- Testing may be too broad: Many at-home food allergy tests measure IgE levels for a long list of possible allergens. While this might seem beneficial, it can actually cause misleading results because it is possible to have elevated IgE for an allergen without actually having an allergy. This is known as a false positive result, and it is more likely with a broad allergy test.
- Risk of false negative result: An actual allergy does not always cause blood levels of IgE to be increased. The risk of this type of false negative result can vary for different kinds of allergens and may occur due to impurities in the food extract that is used. A false negative result may cause someone to feel safe consuming a food that they are allergic to, which can trigger an immune response.
- Limited medical consultation: Reviewing your symptoms and when they have occurred is a fundamental part of interpreting food allergy test results, but many at-home food allergy tests provide limited or no consultation with a doctor or allergist.
- Lack of insurance coverage: At-home food allergy tests are not usually covered by insurance, so you should expect to pay the full cost with your own money.
If you have symptoms of a possible food allergy, at-home testing should not be done in lieu of consulting with a physician. A doctor can best address the pros and cons of different kinds of allergy tests.
Types of At-Home Food Allergy Tests
Most at-home food allergy tests are self-collection tests, which means that you take a sample at home and send it to a lab where it can be analyzed.
There are many types of tests available, and only tests that measure immunoglobulin E (IgE) in the blood are known to potentially help identify food allergies. Other types of tests are considered to be unvalidated and unproven and are not recommended by most experts.
Tests of allergen-specific IgE levels use a blood sample that is taken by pricking your finger with a small needle. A test may include levels for one or more allergens. Although broad tests may seem beneficial, doctors generally recommend against them because of the risk of misleading results.
Interpreting At-Home Food Allergy Test Results
Results from at-home food allergy tests are normally provided through a website or smartphone app. The test report typically lists the levels of IgE for specific allergens and may indicate whether those levels are low, medium, or high.
It is important to remember that IgE levels alone are not able to diagnose a food allergy. People without an allergy can have an elevated IgE, and people with an allergy do not always have higher IgE for that allergen.
For this reason, diagnosis of a food allergy must involve consultation with a doctor. By reviewing any allergy symptoms and their potential triggers, a doctor can most effectively interpret an allergy blood test.
A positive test may show a higher likelihood of a reaction to a particular allergen, but IgE levels do not definitely prove an allergy exists. Even when an allergy exists, IgE levels do not correspond to the severity of the allergy.
In many cases, a negative result on a food allergy blood test is an indication that you are tolerant of that food and can consume it without having an allergic reaction. However, this is not always the case, which is why test results must always be interpreted by a physician in the context of past allergy symptoms.
Even though a test report may offer a simple tool for seeing your IgE levels for specific allergens, reviewing your test results with your doctor or an allergist is essential to fully understanding whether you are likely to have a food allergy.
Are test results accurate?
Blood tests for allergen-specific immunoglobulin E are a useful tool in identifying possible allergies, but they are not perfect. IgE levels do not perfectly correspond to actual allergies, so it is possible to test positive when you are not actually allergic or test negative when you really do have an allergy.
Due to cross-reactivity of various antigens, a false positive blood test may occur.
Some other factors that can affect the overall accuracy of food allergy testing include:
- Lack of established reference ranges: For some types of foods, there is no consensus about what levels of IgE are most likely to correctly indicate a food allergy. In addition, most studies to validate IgE levels have been done in children, so there may be more difficulty in interpreting test results in adults.
- Variation among laboratory methods: There are different methods and technologies for analyzing blood for allergen-specific IgE. Results are not always interchangeable between them, which may create variability in accuracy depending on how the laboratory analysis is conducted.
Do I need follow-up tests?
Follow-up exams may be necessary if there are indications that you may have a food allergy. If you have symptoms of an allergy or test positive on an at-home food allergy test, you should talk to your doctor. Follow-up testing may be coordinated by a doctor who specializes in allergies, known as an allergist.
In addition to reviewing your overall health and symptoms, other tests may be recommended. Examples of other allergy tests include:
- Skin tests: These are the most common type of allergy test and involve exposing the tissue just under the skin to one or more specific allergens and observing any reaction. This testing must be done with a trained medical professional in case an allergic reaction occurs.
- Oral food challenge: Considered the gold standard for diagnosing food allergies, this test involves eating predefined quantities of a specific food and being checked for a reaction over several hours. As with skin tests, for safety reasons an oral food challenge must be done in a medical setting with a health professional.
- Elimination diet: In some cases, a doctor may recommend avoiding a specific food for a period of time to see if allergy symptoms go away.
Questions for your doctor after at-home food allergy testing
If you have taken an at-home food allergy test, some of these questions may be helpful as you discuss your test results with your doctor:
- Do any of my test results indicate a potential food allergy?
- Should I change my diet in any way?
- What other allergy tests do you recommend?
- Would it be beneficial for me to consult with an allergist?
- If my symptoms are not being caused by a food allergy, what might be causing them?
Comparing at-home food allergy testing and food allergy testing ordered by a doctor
At-home food allergy tests can be purchased without a prescription, making it simple to have your blood tested for IgE levels associated with specific allergens. However, it’s important to be aware of how this testing compares with typical food allergy testing ordered by a doctor.
A major difference is that a doctor can prescribe tailored allergy testing based on your situation. This includes deciding between a skin or blood test as well as determining the allergens that have the highest potential to be causing your symptoms.
Once the results from doctor-prescribed tests are ready, the doctor carefully interprets those results in the context of your symptoms. With at-home tests, you may receive a detailed report, but in-depth medical consultation about your results is not always included.
Doctor-prescribed allergy blood tests normally involve a blood sample that is taken from a vein in your arm. At-home food allergy tests, on the other hand, use drops of blood that come from pricking your finger with a small needle.
Costs can also vary depending on how and where your test is conducted. Health insurance providers often pay for at least part of allergy testing if it is prescribed by a doctor. For at-home food allergy testing, you will normally have to pay the full cost yourself.
Comparing food allergy and food sensitivity tests
Testing for food allergies and sensitivities is different because the underlying nature of the reaction itself is different. Food allergies are tied to an immune response, so food allergy testing looks for signs of an abnormal immune response.
Food sensitivities can have different underlying causes, so testing for them depends on the symptoms. However, tests for food intolerances or sensitivities do not measure IgE or other indicators of immune response.