Allergy Testing Options

October 2022  |  Linda Armstrong  |  ✓  Medically reviewed by: Gary Falcetano, PA-C, AE-C; Fabio Iachetti, MD; Eva Södergren, PhD, MSc 

A licensed Physician Assistant with more than 25 years of diverse experience in emergency and disaster medicine, primary care, and allergy and immunology, Gary Falcetano is the U.S. Clinical Affairs Manager for Allergy in ImmunoDiagnostics at Thermo Fisher Scientific. Fabio Iachetti is a licensed physician with more than 15 years of diverse experience in several disease areas such as allergy, CV, pain, GI, rheumatology, urology, and diabetology. He is a Senior Medical Manager for Allergy in ImmunoDiagnostics Global Medical Affairs at Thermo Fisher Scientific. A nutritionist by training, Eva Södergren now works as a Senior Scientific Advisor for Allergy on the Medical and Scientific Affairs team for Thermo Fisher Scientific’s ImmunoDiagnostics division.

There are several different options for allergy testing, including blood tests, skin-prick tests (SPTs), and food challenge tests. Together with your healthcare provider, you can decide which test is best for you. After your elected allergy test is performed, the results are reviewed by your healthcare provider alongside your medical history to help establish an accurate diagnosis. 

Blood Tests

A blood test to aid allergy diagnosis is a quick and simple way for your healthcare provider to get answers to your underlying allergy questions. The test, also called a specific IgE (sIgE) blood test, provides informative results that indicate the levels of allergen-specific IgE antibodies in the blood. These antibodies are an indicator of allergic sensitization and, in context of an allergy-focused medical history, can help your healthcare provider determine if you are allergic and to what.

How Blood Tests Work

  1. A small sample of blood is drawn.
  2. The blood is sent to a laboratory for analysis. 
  3. The results are returned a few days later for your healthcare provider to interpret alongside your symptoms and medical history. 

This powerful diagnostic tool can reveal potential sensitization to hundreds of possible allergens. Blood testing has fewer limitations on who can receive it or when it can be performed compared to other types of testing. Learn more about the benefits of specific IgE blood testing. Or explore a list of frequently asked questions

Types of Blood Tests

There are two broad types of specific IgE blood tests: whole allergen tests and allergen component tests. Paired with a symptom history and physical exam, whole allergen tests help your healthcare provider to determine if you’re sensitized to a specific allergen or group of allergens.

Meanwhile, testing with allergen components helps providers identify the specific molecules (e.g., proteins, carbohydrates, enzymes) that may cause reactions. Knowing which molecules you’re sensitized to may help your provider determine if there could be an increased risk for a severe systemic reaction.

Additionally, testing with allergen components might reveal to providers that you can tolerate an allergen in a specific form. For example, if you have an egg allergy, this testing may suggest that you’re likely to tolerate baked eggs but not lightly cooked or raw eggs. (That means you may be able to eat baked goods such as sweets, breads, and more.)

Those healthcare providers who have used blood tests for decades may be most familiar with the term radioallergosorbent test (RAST), which measures specific IgE but is actually a term for an older technology. In fact, it doesn’t represent modern specific IgE blood tests for allergies, and any literature about RAST likely doesn’t apply to current tests. 

Skin-Prick Tests (SPTs)

With SPTs, your skin is directly exposed to suspected allergens and observed for signs of a reaction. 

How SPTs Work

  1. The upper layer of your skin is punctured or scratched to introduce a very small amount of a suspected allergen to your immune system. 
  2. A reaction similar to a mosquito bite may appear, usually within 20 minutes, indicating the presence of specific IgE for (sensitization to) this allergen.

Blood Tests vs. SPTs

Specific IgE tests and SPTs are frequently used to help diagnose allergies. But how do you and your healthcare provider choose between them? Here are some key differences followed by a handy chart to further highlight the comparison. 

  • Testing Personnel. While rare, SPTs can cause life-threatening anaphylaxis.1 Thus, SPTs typically must be administered and interpreted by allergy specialists, who are trained to deal with anaphylaxis, and in a facility that is capable of providing life-saving tactics and equipment.2-3 Meanwhile, blood tests, which carry no risk of anaphylaxis, can be ordered by almost any healthcare provider and carried out via a blood draw in a clinic or perhaps a laboratory.4
  • Speed to Diagnosis. SPT results are often obtained in less than an hour, and blood test results are usually back from the lab within a few hours to a few days.3 However, when you consider that it may take weeks to months to secure an appointment with a specialist—and that you may need to see a general practitioner first to get a specialist referral—a blood test may actually lead to a faster diagnosis.
  • Comfort. With an SPT, the provider places allergen droplets on the skin and then scratches over them to get the allergen into your skin. Or, he or she uses a sharp device to prick your skin up to 50 times with different allergens.4 A blood test typically requires a single needle stick for a blood draw. 
  • Medications. For best results, patients must avoid most antihistamines for at least seven days prior to SPTs. Healthcare providers may also recommend stoppage of other pharmaceutical such as psychiatric medications and beta-blockers prescribed for high blood pressure.5 Specific IgE blood tests allow you to remain on these medications prior to testing.
  • Skin Disease. For accurate SPT interpretation, you need an adequate area of normal skin. Thus, SPTs may not be an option if you have widespread skin issues such as atopic dermatitis or eczema. Meanwhile, skin condition has no effect on blood testing.6
  • Age and Skin Reactivity. Skin reactivity can vary with age. So while it has no impact on blood testing effectiveness, SPT reliability isn’t as high in infant and elderly populations.6
  • Skin Pigmentation. Some sources suggest that it may be more difficult to accurately interpret SPT results in those with increased skin pigmentation.7


Key Test Differences 

Specific IgE Blood Test 


No Risk of Anaphylaxis

May be Performed by Most Healthcare Providers


Same Day Results

Not Affected by Medications


Not Impacted by Skin Pigmentation/Condition


Effective for People of Any Age


Food Allergy Challenge Tests

A challenge test, in connection with a blood test or an SPT, is a powerful diagnostic tool. Also called an oral food challenge (OFC), it is used to establish a correct diagnosis, which can be guided by the results from an SPT or a blood test. A challenge test can be used to confirm a food allergy or to determine whether you have outgrown a food allergy. 8

How Food Allergy Challenge Tests Work

An OFC typically has three steps:8

  1. You are fed a small portion of a food to which you have a suspected allergy.
  2. You are monitored closely for any clinical symptoms, usually in a medical (clinic or hospital) setting. 
  3. If there is no reaction, you consume increasingly larger portions of the food, up to a serving size. If a reaction occurs, the test stops.

To properly manage and treat allergies, it’s important to first understand exactly what is causing symptoms. Talk to a healthcare provider about allergy testing options. To get the conversation started, we compiled a few questions designed to help healthcare providers get a full picture of your symptoms. You can review your answers together during your office visit.

Tools for Understanding Allergies


Track allergy symptoms and prepare for a visit with a healthcare provider.

Learn about specific allergens, including common symptoms, management, and relief. 

Are you a healthcare provider? Get comprehensive information on hundreds of whole allergens and allergen components.

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  2. Kwong KY, Eghrari-Sabet JS, Mendoza GR, Platts-Mills T, Horn R. The benefits of specific immunoglobulin E testing in the primary care setting. Am J Manag Care. 2011 Dec;17 Suppl 17:S447-59. PMID: 22214511.
  3. Ansotegui IJ, Melioli G, Canonica GW, Caraballo L, Villa E, Ebisawa M, Passalacqua G, Savi E, Ebo D, Gómez RM, Luengo Sánchez O, Oppenheimer JJ, Jensen-Jarolim E, Fischer DA, Haahtela T, Antila M, Bousquet JJ, Cardona V, Chiang WC, Demoly PM, DuBuske LM, Ferrer Puga M, Gerth van Wijk R, González Díaz SN, Gonzalez-Estrada A, Jares E, Kalpaklioğlu AF, Kase Tanno L, Kowalski ML, Ledford DK, Monge Ortega OP, Morais Almeida M, Pfaar O, Poulsen LK, Pawankar R, Renz HE, Romano AG, Rosário Filho NA, Rosenwasser L, Sánchez Borges MA, Scala E, Senna GE, Sisul JC, Tang MLK, Thong BY, Valenta R, Wood RA, Zuberbier T. IgE allergy diagnostics and other relevant tests in allergy, a World Allergy Organization position paper. World Allergy Organ J. 2020 Feb 25;13(2):100080. doi: 10.1016/j.waojou.2019.100080. Erratum in: World Allergy Organ J. 2021 Jun 17;14(7):100557. PMID: 32128023; PMCID: PMC7044795.
  4. Cleveland Clinic [Internet]. Cleveland OH: Cleveland Clinic; 2022. Available from:
  5. American College of Allergy, Asthma & Immunology [Internet]. Arlington Heights, IL: American College of Allergy, Asthma & Immunology; 2022. Available from:
  6. Robinson M, Smart J. Allergy testing and referral in children. Aust Fam Physician. 2008 Apr;37(4):210-3. PMID: 18398515.
  7. Jean T, Kowng, KY, Redjal N (2014) Variability in Measurement of Allergen Skin Testing Results Among Allergy-Immunology Specialists. J Allergy Ther. 5:60. doi:10.4172/2155-6121.1000160
  8. American Academy of Allergy Asthma and Immunology [Internet] 2. What do patients and caregivers need to know about oral food. challenges. Accessed August 2022