Allergy Tests: What Are They and How Can You Get One?
Key takeaways:
There are a range of different allergy tests. But their utility is limited and depends on your type of allergy.
If you have a history of allergy symptoms, your healthcare professional may recommend you have a blood test or skin test to check for allergies. If you think you’re allergic to a specific food, your healthcare professional might order a food-challenge test.
There’s no way to test for every possibility because so many things can cause allergies. The best way to make sure you’re getting the right test is to consult with your healthcare team so you don’t waste your time and money.
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Allergies happen when the immune system mistakes something harmless in the environment as a threat. Allergies cause symptoms that range from annoying to life-threatening. If you have them, you may be wondering if allergy testing might be helpful. Testing is helpful in certain situations, but it’s not a great option for everyone.
The goal of most allergy testing is to pin down the cause of a reaction that already happened. Testing for allergies can give you useful information, but you don’t always need it — even if you’ve had an allergic reaction before. Let’s take a closer look at when allergy tests are needed and how you can get one.
How do allergy tests work?
Allergy testing checks to see if you have IgE antibodies in your body that are programmed to recognize certain targets as an allergen. An allergen is a target that causes an allergic reaction.
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Common allergens include:
Pollen
Cockroaches
Dust mites
Cats
Peanuts
Cow’s milk
There are a variety of ways to test for allergies. The best ways are:
Skin testing
Blood testing
Food challenges
Do you need an allergy test?
Most people don’t need to be tested for allergies. But, sometimes, allergy testing can provide important information. Knowing what you’re allergic to can help you avoid that trigger in the future. But you need to have a clear history of an allergic reaction for an allergy test to be useful.
Allergy testing is recommended when:
You’ve had a severe or dangerous reaction in the past.
You have a reaction over and over again.
Allergies or asthma run strongly in your family.
You need to make a healthcare decision based on the result (for example, deciding if it’s safe to take an antibiotic you think you might be allergic to).
In general, you don’t need allergy testing if:
You’ve never had an allergic reaction.
You had a reaction, but it was mild and easily treated (like a stuffy nose during pollen season).
The cause of your reaction was obvious.
You’re unlikely to be exposed to the trigger again.
You wouldn’t change anything based on the results of allergy testing.
Your symptoms don’t fit the profile of an allergic reaction (like, redness, itching, or inflammation).
Different types of allergy testing
There are many different types of allergy tests. Your allergist will determine the best test for you based on your symptoms and the allergen they suspect is causing your symptoms. Here’s a closer look at each allergy test and when it’s used.
Skin test | Blood test | Food challenge | Home test | |
|---|---|---|---|---|
How it works | In a skin prick or scratch test, a drop of allergen is placed on the skin or gently scratched into the skin. A rash or wheal will appear if you have an allergy to the skin testing. | A sample of your blood can be drawn in a lab and then be tested against a set of common allergens. Blood testing can also look at cells involved in allergies and inflammation (like eosinophils). | You eat some of the food you might be allergic to, and a medical team watches how you respond. If you have a reaction, they give you medications to keep you safe, and the test ends. | This test involves putting spots of blood on a card and mailing it into a lab. Your blood is tested against a set of common allergens and results are mailed back to you in a few weeks. |
Who is it best for? | People who’ve had an allergic reaction and need to know what caused it | People who can’t get skin tests or when an allergist isn’t available People who want the convenience of a single test, instead of having to visit a specialist | People at risk of having an allergic reaction to a food who need to know for sure | It’s most useful if you have a clear history of an allergic reaction and some idea of what caused it. If you don’t, you might end up spending a lot of money. |
Who should avoid it? | It’s not safe if you’ve had a severe (or anaphylactic) reaction to a small amount of allergen. | It’s not a good test for most people because skin tests are better at finding allergies. | Anyone with a known food allergy Anyone with suspected food intolerance | Anyone with life-threatening or serious allergies Anyone needing accurate results Anyone making big changes based on the results |
Pros | It tests for most common allergens (dog, cat, ragweed, egg, peanut, pollen, and penicillin). It’s done in an office setting and doesn’t require a blood draw. Results are available right away. | A blood test takes less time than skin testing. It may be safer or more practical for some. | It can confirm the existence (or absence) of a food allergy. | Private Convenient You get to decide what to test for and what to do with the results. |
Cons | Requires a visit to a specialist Can be uncomfortable May bring on a bad reaction if you test positive for an allergen | Not as accurate as skin testing Takes longer to get results Not available for all allergens | Can take several hours Risk of a severe reaction Can be expensive | Not regulated Less accurate than skin or blood tests Limited number of allergens to test for |
Other types of allergy tests
There are some other types of allergy tests used in specific circumstances:
Patch testing: Patch tests look for skin reactions to creams, detergents, or chemicals in the environment. A small amount of a possible allergen is placed on a small pad and taped to the skin on your back. After a few days, the allergist removes the pad and checks your skin for a rash.
Intradermal testing: Sometimes, a skin scratch test doesn’t show a reaction even when it seems like it should. In those cases, it can be helpful to test a bit more deeply with intradermal testing. Here, a small amount of allergen is injected under the skin with a tiny needle. If you’re allergic, you’ll start itching in the spot where it was injected.
Total serum IgE: Total serum IgE looks at all of your IgE antibodies added together. It won’t tell you what you’re allergic to, but it can figure out if you’re likely to be allergic to something. This test might be helpful if you’ve had a reaction and you don’t know if it was caused by an allergy or something else. It’s also sometimes used in babies with bad eczema to see if allergies are part of the problem.
Allergy tests that are not recommended
Unorthodox allergy tests (like hair analysis, pulse testing, and IgG4 testing) aren’t recommended. Many of these tests haven’t been studied. Others have been studied and have been shown to be inaccurate. Using an inaccurate test can be frustrating, expensive, and confusing. If you aren’t sure about a particular test or method, talk with a healthcare professional.
How to get an allergy test
If you have congestion, watery eyes, itching, and a runny nose, you might want to know the exact cause. Most primary care providers can help you evaluate your mild-to-moderate symptoms and decide if allergy testing is worthwhile. They can also help you decide what allergy test is right for your symptoms and make sure the correct type of test is ordered.
For more serious allergies and anaphylaxis, the American Academy of Allergy, Asthma and Immunology recommends seeing an allergist. An allergist has specialized training in dealing with serious allergies.
It’s possible in many states to order some of your own lab tests without a prescriber. Of course, if you order the wrong tests, it’s money down the drain. And when you order your own lab tests, there’s no one to help you interpret them. For some people, this is an acceptable risk — but it’s best to discuss with a medical professional first.
Getting your allergy test results
It might seem like allergy testing should give you a simple answer, but it often doesn’t work that way. Here’s why:
Most allergy tests are quantitative. That is, they give you a number, not a yes-or-no answer.
Many times, allergy test results don’t fit with real-life experience. It’s common to test positive for something that isn’t a problem for you.
Tests don’t always agree with each other. Different types of tests — even different brands or methods of testing — can tell you different things.
Allergy tests will never give you a final answer because allergies change over time.
For these reasons, it’s important to have a conversation with a healthcare professional about what to do with your results. They can help you figure out how to use your results to avoid allergic reactions in the future.
The bottom line
You can test for allergies, but allergy tests aren’t perfect. Often, test results are confusing or ambiguous. Sometimes a test might suggest you have an allergy to something that has never bothered you.
For all of these reasons, allergy tests are most useful when you’ve worked with an allergist first to make an educated guess about your allergies. Once you have an idea of what allergy you might have, you can do the right tests to find out exactly what you need to know.
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References
Alsaggaf, A., et al. (2019). Estimating cost-effectiveness of confirmatory oral food challenges in the diagnosis of children with food allergy. Global Pediatric Health.
American Academy of Allergy, Asthma & Immunology. (2023). Allergy testing.
Sicherer, S. H., et al. (2012). Allergy testing in childhood: Using allergen-specific IgE tests. Pediatrics.
