Key takeaways:
There are several types of allergy test, but the best choice depends on your symptoms and suspected triggers.
Skin tests, blood tests, and food challenges can help diagnose allergies when they’re used alongside your symptom history.
If you have allergy symptoms, a healthcare professional may recommend a blood or skin test. If a specific food is suspected, they may order a food challenge test.
You can’t test for every possible allergen. To avoid unnecessary time and cost, it’s best to work with your healthcare team to choose the right test.
Allergies happen when your immune system reacts to something that’s usually harmless. Allergy symptoms can range from annoying to life-threatening. If you have them, you may be wondering if allergy testing might be helpful. While testing can be useful in certain situations, it’s not always necessary — and it doesn’t always give clear answers. Knowing when testing is helpful, and which types are reliable, can help you avoid unnecessary costs and get the most accurate diagnosis.
How do allergy tests work?
Allergy tests identify certain substances (called allergens) that may be causing an allergic reaction. Common allergens include:
Pollen
Cockroaches
Dust mites
Cats
Peanuts
Cow’s milk
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There are a variety of ways to test for allergies, and they all work a bit differently. The best tests include:
Skin testing
Blood testing
Food challenges
Different types of allergy testing
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 (like hives or itching), 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’s 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 the best test for most people, since 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. | It’s private. It’s 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 healthcare professional 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 in the skin 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: When you have an allergy, your immune system produces specific antibodies called immunoglobulin E (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.
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 in these cases:
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 in these instances:
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).
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.
What to expect during an allergy test
If you’ve never had an allergy test before, you may not know what to expect. Here are some key points to keep in mind.
How should I prepare for an allergy test?
Before getting a skin prick test (the most common allergy test), it’s best to avoid certain medications that can interfere with the test. Follow the healthcare professional’s specific instructions. But here are some general guidelines:
Stop taking any antihistamine pills (like Claritin or Benadryl) or nasal sprays (like Azelastine) 7 days before the test.
Don’t take medications like Tagemet, Pepcid, or Zantac 1 day prior to testing (these medications contain a form of antihistamine).
Don’t take a tricyclic antidepressant medication (like Elavil).
Don’t take beta-blocker medications (like metoprolol)
If you’re getting an oral food challenge test, you may also have to stop taking antihistamines a few days before the test. Blood allergy tests don’t usually require any preparation.
Talk to your healthcare team about specific ways to prepare for your test and discuss with them before stopping any prescription medications.
How long does an allergy test take?
How long allergy tests take depends on the type of test you’re getting. Here’s an overview of each test:
A blood test is the fastest because it just requires a regular blood draw. If you’re doing the home test, it will take days to get results.
A skin prick test takes about 5 to 10 minutes to apply to the skin, and then you wait 30 minutes to see if there’s a reaction.
An oral food challenge usually takes about 4 hours or longer. This includes the observation period after eating the specific food.
When should I get my allergy test results?
How long it takes to get your results also depends on the type of test you’re getting. Here’s what to expect:
Skin prick test results usually take about 20 to 30 minutes to see the results.
The results of an oral food challenge are immediate. You should know if you have an allergy right after the whole test is complete.
A blood test can take a few days, depending on the lab you’re using.
Interpreting 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. This means 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.
There’s no final answer. 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.
Frequently asked questions
Most insurance plans will cover allergy testing when it’s medically necessary and ordered by a healthcare professional. Coverage may vary based on your plan, and you may still have out-of-pocket costs like a copay.
The price of allergy testing depends on the type of test. One study showed that the average cost of blood testing was $161 and that skin prick testing was $247. If your insurance plan covers allergy testing, your out-of-pocket costs may be less. Before scheduling testing, check with your insurance company to understand your coverage.
The 3-day rule is a feeding approach for infants to help identify specific food intolerances. It works by giving the child a single-ingredient food for 3 days before introducing another new food. After each new food is introduced, the child is monitored for allergic reactions, like rashes or vomiting.
A recent federal law (called the FASTER Act) listed sesame as the ninth major food allergen. This is added to the previous eight major food allergens, which included:
Milk
Eggs
Fish (like bass or flounder)
Crustacean shellfish (like lobster and shrimp)
Tree nuts (like almonds and walnuts)
Peanuts
Wheat
Soybeans
Most insurance plans will cover allergy testing when it’s medically necessary and ordered by a healthcare professional. Coverage may vary based on your plan, and you may still have out-of-pocket costs like a copay.
The price of allergy testing depends on the type of test. One study showed that the average cost of blood testing was $161 and that skin prick testing was $247. If your insurance plan covers allergy testing, your out-of-pocket costs may be less. Before scheduling testing, check with your insurance company to understand your coverage.
The 3-day rule is a feeding approach for infants to help identify specific food intolerances. It works by giving the child a single-ingredient food for 3 days before introducing another new food. After each new food is introduced, the child is monitored for allergic reactions, like rashes or vomiting.
A recent federal law (called the FASTER Act) listed sesame as the ninth major food allergen. This is added to the previous eight major food allergens, which included:
Milk
Eggs
Fish (like bass or flounder)
Crustacean shellfish (like lobster and shrimp)
Tree nuts (like almonds and walnuts)
Peanuts
Wheat
Soybeans
The bottom line
Allergy testing can be helpful, but the 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.
Why trust our experts?
References
American College of Allergy, Asthma & Immunology. (2023). Testing & diagnosis.
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). All about allergy testing.
American Academy of Allergy, Asthma & Immunology. (2023). Allergy testing.
Kwong, K. Y., et al. (2023). Cost of serum versus skin allergy testing among medicare fee-for-service beneficiaries in the United States. JHEOR.
Massachusetts General Hospital. (2021). Preparing for an oral food challenge.
Sicherer, S. H., et al. (2012). Allergy testing in childhood: Using allergen-specific IgE tests. Pediatrics.
University of Mississippi Medical Center. (n.d.). Preparation for allergy testing.
U.S. Food and Drug Administration. (2024). The FASTER Act: Sesame is the ninth major food allergen.
