About the Test
Purpose of the test
The purpose of an at-home allergy test is to see if the blood shows signs of being sensitized to a particular substance. Sensitization found on the test may indicate the presence of an allergy.
What does the test measure?
At-home allergy tests measure levels of immunoglobulins in the blood. Immunoglobulins, or antibodies, are specific proteins produced by the immune system and are involved in immune responses.
There are different types of immunoglobulins that can be measured, but immunoglobulin-E (IgE) is most clearly associated with allergies. Elevated levels of IgE can reflect a risk of immune overreaction. Allergy tests look for high IgE levels linked to specific substances that may be found in certain plants or foods, which can be a sign of a possible allergy.
Some tests also measure levels of immunoglobulin-G (IgG), but these do not accurately reflect allergies. While IgG is produced as part of an immune response, high levels are unrelated to an actual allergy. For example, children who outgrow a food allergy may show decreased IgE levels and elevated IgG levels as they develop tolerance.
Every at-home test will list which types of allergens it is testing for and should state whether it is measuring IgE or IgG levels. Test results may show the actual levels of immunoglobulins related to specific potential allergens and/or list whether those levels were considered to be low, medium, or high.
Benefits and Downsides of At-Home Allergy Tests
As a safety precaution, a number of common allergy tests, such as skin tests, can only be performed in a medical setting. Tests that include direct allergen exposure are not available at home.
At-home testing is an option for allergy tests that use a blood sample, but there are pros and cons of at-home versus in-clinic testing.
Benefits of at-home allergy testing include:
- Convenience: With the ability to take the test in the comfort of your own home, you can easily find a convenient time for testing on your schedule.
- Easy to use: At-home tests involve straightforward instructions that make the process simple.
- Clear pricing: Although you usually have to pay out-of-pocket, the costs of at-home tests are made clear up-front.
Downsides to at-home allergy testing include:
- Risk of false positives: Elevated immunoglobulin levels do not always reflect a true allergy, creating a risk of the test reporting an allergy when none truly exists (false positive).
- Screening is too broad: At-home tests tend to be very broad and may look for dozens of types of allergens. But broad testing can worsen the risk of false positives, which is why most laboratory tests are narrow and focus on allergens that are suspected based on your symptoms.
- Results lack context: Without your doctor there to review results, it can be hard to understand their significance. False positives received without proper context may cause you to unnecessarily avoid certain foods, plants, or materials.
- Need for follow-up testing: Because at-home testing is not definitive, proving the presence of an allergy requires additional testing conducted by your family doctor or an allergist.
- Test quality can vary: The design and quality of test kits can vary, which may affect the reliability of results. Some tests measure only IgG which is not a reliable marker for allergies.
- Not covered by insurance: You will almost always have to pay entirely out-of-pocket for at-home allergy tests.
- Not offered in some states: Certain states restrict the availability of at-home testing.
Types of At-Home Tests
Almost all at-home allergy tests involve taking a small blood sample from your finger. The blood sample is placed on a paper or test strip and then sent to a lab for allergen analysis. Once your sample is received, test results are normally available within a few business days.
Differences in tests include:
- Which immunoglobulins they test for: IgE is most directly associated with allergies. Some tests screen for IgG, but high levels of IgG have not been proven to reflect an underlying allergic response. Kits that measure only IgG should not be used for allergy testing. Also, some may request a hair sample. There is no IgE in hair.
- Which allergens are included: Look carefully at the list of allergens included on the test, especially if you suspect that you have a specific allergy. Remember that testing for more allergens isn’t always better because of the risk of false positives.
- How results are delivered: The type of test report and the level of detail provided can vary depending on the brand and model of test.
While these factors may help you understand your at-home testing options, the best allergy testing is done in conjunction with your doctor.
Interpreting At-Home Test Results
Results will generally show whether your blood sample included immunoglobulin levels that could be a sign of an allergy. They may classify the level as low, medium, or high for each allergen.
Only a doctor can conclusively diagnose an allergy, so remember that these test results are not definitive. For example, the test may show an allergy to a substance that you can’t remember having had a reaction to. This may be a sign of a false positive result.
Because of the chance of false positive results, it’s best to talk with your doctor if you’re concerned about allergies and planning on using a home test kit. More precise testing can be done by a specialist, known as an allergist, who can order the most appropriate type of test based on your symptoms.
If you are confirmed by your doctor to have an allergy, they can discuss a plan for treatment and avoiding allergen exposure.