Table of Contents
If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.
From seasonal allergies to food allergies, these prevalent conditions can significantly impact your quality of life. While seasonal allergies may keep you indoors all spring, food allergies can be dangerous or even life-threatening.
If you’ve heard that allergic reactions are becoming more common, it’s not your imagination. Recent research shows that many allergies are becoming more widespread in the United States and have roughly doubled in the past 20 years (CDC, 2016).
While they’re not sure exactly what’s causing the rise, there are some theories, and guidance has changed somewhat over the past decade. Researchers used to tell parents to avoid exposing their children to particular foods until a certain age; however, new guidance suggests that earlier exposure might be the key to preventing food allergies later in life.
If a person experiences an allergic reaction, it can be difficult to put your finger on the source. People with one allergy are also more likely to experience other allergies as well, making testing crucial. Getting an allergy test can help identify triggers and manage symptoms.
There are several different kinds of allergy tests, including skin and blood tests. Each has pros and cons, and it’s often necessary to use more than one type of test to get a conclusive answer about what’s causing your symptoms.
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What is an allergic reaction?
Your immune system has a set of complex processes for responding to foreign invaders like bacteria, viruses, and parasites.
Sometimes, that system can mistakenly identify something friendly as harmful, triggering those responses inappropriately. While there are many types of allergic reactions, that’s the basic premise.
These immune responses range from a runny nose or itchy watery eyes to full-blown anaphylaxis, making it difficult or impossible to breathe and even be deadly without treatment.
Allergic reactions may also cause skin swelling, hives, nausea, vomiting, and more. The most common types of allergies are allergic rhinitis and food allergies, which we’ll look at below.
Allergic rhinitis is your classic sneezing, runny nose, red eyes, and stuffed-up sinuses. This type of allergy comes with exposure to pollen, mold, pet dander, and other airborne allergens. Over 50 million Americans are affected by allergic rhinitis every year, and it’s becoming more common in urban environments (Birch 2020)
In susceptible people, allergic reactions to seafood, nuts, dairy, and other foods can cause symptoms like anaphylaxis—the rapid onset of swelling in the airways and difficulty breathing that requires immediate medical attention. Anaphylaxis is very serious and can even be fatal. One study estimates that roughly 26 million American adults are allergic to at least one food (Gupta, 2019).
People can also be allergic to insect bites, bee stings, and certain drugs, like penicillin.
There are plenty of treatments for allergy symptoms, including nasal sprays for allergic rhinitis and epinephrine pens for food allergies. However, the best way to manage allergies is to avoid contact with what caused the problem in the first place. To do that, you’ll need an allergy test.
Types of allergy tests
There are several types of allergy tests, each of which can help determine what might trigger your reaction. Let’s take a look at each and how they work.
Examining your medical history
Sometimes, it’s pretty obvious what you’re allergic to, and a healthcare provider can figure it out just by asking you a few questions about your medical history. If that’s the case, they won’t need to go further with other tests.
If they still need to use one of the tests below, knowing your clinical history can help get a better idea of which test to choose.
A simple blood test, also known as serum IgE testing, is often used. IgE is the molecule your body makes if you’re allergic to something, and each IgE molecule is specific for a particular allergen. The lab will mix your sample with one or more known allergens to determine if your IgE molecules react with it.
These panel tests are expensive, though, and not something performed routinely. A healthcare provider will most likely choose this test if they don’t know what caused your allergic reaction or if they suspect you might be allergic to more than one thing.
There are several allergy skin tests available. The most commonly used one is the skin prick test, also called a scratch test.
In this test, a small amount of a suspected allergen is placed on a tiny needle and then pricked or scratched into the top layer of your skin. After about 15 minutes, if a bump (or wheal) has developed on the skin, it’s an indication that you might be allergic to that substance.
Many allergens can be tested at the same time using this test. The back of your wrist is a good spot for skin pricks as you can perform multiple skin pricks at once, quickly narrowing down the offending allergen.
Sometimes, a provider may choose to do a deeper skin prick test called intradermal skin testing, which involves injecting a larger quantity of a suspected allergen deeper beneath the skin. Some people with food allergies don’t react to the more superficial test, which can be more sensitive.
The patch test
In this test, a patch containing an allergen is placed on the skin, left for around 48 hours, and then removed. The reaction is evaluated about an hour after the patch has been removed.
In a challenge test, a doctor will have you ingest a suspected allergen and watch for a reaction. This is often used to test for food allergies, but there is a risk of a severe reaction with challenge tests. Oral challenge tests are used when blood and skin prick tests don’t provide conclusive results.
Which allergy test is best?
Now that we know a bit about allergy tests, you may ask which allergy test is best?
The simplest answer is that they are all fairly accurate, but each has its own set of pros and cons. Your allergist may need to try more than one type of test before you get a conclusive answer.
One small study found that the skin prick test was superior to the deeper skin and blood tests in determining if people were allergic to mice (Sharma, 2008). A more comprehensive review of the research found that blood and skin testing often yielded different results, meaning they can’t be used interchangeably.
Instead, these tests should be used together to get the best answer. Using only one testing method, the review notes, could result in allergy misdiagnosis in a quarter of all patients (de Vos, 2014).
Allergy testing for kids
Allergies are the most common chronic condition among children making testing crucial (Robinson, 2008). Once your healthcare provider has taken a thorough clinical history of your child, they can determine the best test to figure out which allergens could be an issue (Sicherer, 2012).
The variety of allergy tests might seem intimidating at first, but it’s good to remember they are all pretty precise. And as we mentioned, the best way to get a clear answer is often using more than one type of test.
Once you know what you’re allergic to, you can work with a healthcare provider to develop a treatment plan and take control of your allergies.
- Birch, K., & Pearson-Shaver, A.L. Allergy Testing. In: StatPearls. Treasure Island (FL): StatPearls Publishing; October 15, 2020. Retrieved from https://www.statpearls.com/ArticleLibrary/viewarticle/17373
CDC. (2016). Age-adjusted percentages (with standard errors) of hay fever, respiratory allergies, food allergies, and skin allergies in the past 12 months for children under age 18 years, by selected characteristics: United States. National Health Interview Survey. https://ftp.cdc.gov/pub/Health_Statistics/NCHS/NHIS/SHS/2016_SHS_Table_C-2.pdf
Gupta, R. S., Warren, C. M., Smith, B. M., et al. (2019). Prevalence and Severity of Food Allergies Among US Adults. JAMA Network Open, 2(1):e185630. doi: 10.1001/jamanetworkopen.2018.5630. Retrieved from https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2720064
Savage, J., & Johns, C. B. (2015). Food allergy: epidemiology and natural history. Immunology and Allergy Clinics of North America, 35(1), 45-59. doi: 10.1016/j.iac.2014.09.004. Retrieved from https://pubmed.ncbi.nlm.nih.gov/25459576/
Sharma, H. P., Wood, R. A., Bravo, A. R., & Matsui, E. C. (2008). A comparison of skin prick tests, intradermal skin tests, and specific IgE in the diagnosis of mouse allergy. The Journal of Allergy and Clinical Immunology, 121(4), 933-939. doi: 10.1016/j.jaci.2008.01.023. Retrieved from https://www.jacionline.org/article/S0091-6749(08)00161-9/fulltext
de Vos, G. (2014). Skin testing versus serum-specific IgE testing: which is better for diagnosing aeroallergen sensitization and predicting clinical allergy? Current Allergy and Asthma Reports, 14(5), 430. doi: 10.1007/s11882-014-0430-z. Retrieved from https://pubmed.ncbi.nlm.nih.gov/24633614/
Sicherer, S. H, & Wood, R. A. (2012). Allergy testing in childhood: using allergen-specific IgE tests. Pediatrics, 129(1), 193-197. doi: 10.1542/peds.2011-2382. Retrieved from https://pubmed.ncbi.nlm.nih.gov/22201146/