Your allergy-like symptoms may not be caused by allergies. Any number of things, including non-allergic rhinitis, food intolerance, and more, might trigger symptoms. And if you don’t have allergies, relief methods such as antihistamines might be ineffective. So, it’s important to get tested.

• You could have non-allergic rhinitis as opposed to an allergy. Symptoms such as a stuffy/runny nose, sneezing, coughing, etc. could be caused by non-allergic rhinitis, which can be triggered by things such as spicy foods, viral infections, alcoholic beverages, medications, dust, smoke, perfumes, humidity changes, etc.³ In fact, an estimated 50 percent of patients with rhinitis (aka hay fever) symptoms may not have allergic rhinitis. For those with non-allergic rhinitis, antihistamines may not affect some symptoms. And according to one study, two-thirds of patients who frequently took low-sedating antihistamines tested negative for specific IgE.⁴

• Instead of a food allergy, you might have a food intolerance. Food allergies and food intolerances are sometimes confused.⁵ The former involves the immune system and can include symptoms such as hives, sneezing, itchy eyes and/or nose, vomiting, stomach cramps, diarrhea, anaphylaxis and more.^5,6 A food intolerance or sensitivity occurs when a person has difficulty digesting a particular food. Symptoms can include intestinal gas, abdominal pain, and/or diarrhea.⁵ A specific IgE blood test for allergies can help your provider determine which food-related condition you’re experiencing.  

To lessen symptoms, it helps to know what’s causing them to inform a proper management plan. Plus, if, like most people, you’re allergic to more than one thing, you may be able to decrease or eliminate symptoms by staying below your symptom threshold.⁸

• Roughly 70 to 80 percent of people with allergies are sensitized to multiple allergens.⁷ For some people, allergy symptoms appear only when they encounter two or more allergens they’re allergic to at the same time. By limiting exposure to one or more of their allergens and reducing the total allergen load, they may be able to better manage their symptoms and reduce the need for pharmacological treatments.⁸ For example, if someone is allergic to dust mites, ragweed pollen, and pet dander, limiting their exposure to pets during pollen season might lessen seasonal hay fever symptoms.

• Understanding allergic triggers can aid management. According to a report published in the Journal of the American Board of Family Medicine, understanding your specific allergic triggers (particularly if you have asthma) can help guide management via allergen avoidance, pharmacological treatments and immunotherapy.⁹ 

Allergies are dynamic in that they can develop and change throughout your lifetime. Identifying your current allergic triggers may help you prevent a severe reaction.

• Allergies can vary over time. In fact, sometimes allergies disappear and return years later.² For example, according to the Food Allergy Research & Education organization, while children can have a shellfish allergy, 60 percent of allergic individuals experience their first reactions as adults.¹⁰

• Mild symptoms may become severe. Although symptoms of food allergy range from mild to severe, they can fluctuate. A food that triggered mild symptoms on one occasion may cause severe symptoms such as anaphylaxis another time.¹¹ 

While everyone has different preferences, blood tests for allergic sensitization may have several advantages over SPTs. Consider one or more of the following facts to fill in the blank.

• According to some studies, skin-prick tests are unreliable in detecting sensitization to some allergens. With suspected food allergies, the overall positive predictive accuracy of SPTs is less than 50 percent.¹² Additionally, in patients with a nut allergy, the SPT detection rate is only 56% compared to 71% for specific IgE blood tests.¹³ And when it comes to diagnosing alpha-Gal syndrome (which may cause a potentially life-threatening reaction to red meat and other mammalian products), SPTs with extracts of pork or beef have been unreliable.^14-16

• One blood draw may be preferred over the 10 to 50 pricks of an SPT. With an SPT, a provider uses a thin needle to prick your skin 10 to 50 times with different allergens. Or he or she may place allergen droplets on your skin and then scratch over them to allow the allergens to enter your skin.¹⁷ For some people, a single blood draw may be more comfortable than an SPT.

• Unlike SPTs, almost any provider (not just an allergy specialist) can order a blood test for allergies. While the risk is low, anaphylaxis can occur because of SPTs. Given this risk for severe reactions, SPTs are only performed by practitioners trained in both administering the test and interpreting its results. (Typically, then, SPTs are only administered by allergists or similar specialists.) Blood tests, however, can be ordered by most general healthcare providers, so you might not need a second appointment (nor additional time and perhaps money) to see a specialist.¹²

• Contrary to SPT results, blood test accuracy isn’t impacted by skin conditions and reactivity. SPTs require an adequate area of healthy skin for effective testing, which means an SPT can’t be performed if there is a widespread skin disease, such as active atopic dermatitis. Additionally, according to an article published in the Australian Family Physician (a peer-reviewed medical journal), skin reactivity may be reduced (thus limiting SPT reliability) in very young children and the elderly.¹²

• Unlike SPTs, specific IgE blood tests don’t require that you stop taking most medications, such as antihistamines. For accurate SPT results, patients must avoid most antihistamines for at least seven days before skin testing. Additionally, beta-blockers, which are often prescribed for high blood pressure, may introduce more risks for a serious reaction to an SPT.¹⁸ Specific IgE blood tests allow you to remain on these medications (and others) before testing. 

While they may not be warranted in all situations, allergen component tests (which are a type of allergy blood test) may provide additional insights regarding severity and food-avoidance precautions.

• Component tests provide deeper insights. While specific IgE testing may help identify whether a person is sensitized to an allergen, component testing aids in identifying the specific proteins that may cause reactions.

• Knowing which proteins you’re sensitized to can help your provider determine if there could be a risk for a severe systemic reaction. Some allergen proteins, such as the storage proteins in peanuts and nuts, can be associated with severe reactions, while others may cause much milder symptoms. Plus, some allergen proteins aren’t destroyed when exposed to heat (e.g., through cooking) and digestion, and they’re more likely to cause severe reactions.

• Meanwhile, as reported by the World Allergy Organization Journal, other proteins that are destroyed by heat and digestion may cause milder local reactions that can be tolerated.¹⁹ So by understanding the specific proteins you’re sensitized to, your healthcare provider can better assess the potential severity of your reaction and create a more effective allergy management plan. Plus, for some people, tests may help their providers determine whether they can tolerate foods they previously thought were off limits. 

Specific IgE tests are an evolution of the RAST, which is a different and much older type of blood test. However, some healthcare providers erroneously believe they’re the same.

Why should allergy sufferers care? If providers reference scientific literature about RAST, it may not paint an accurate picture of today’s testing and its effectiveness. Current specific IgE tests can be more effective than RAST.²⁰

• Modern specific IgE tests are different from RAST.  Blood tests measure the presence of IgE antibodies to specific foods and respiratory triggers. IgE is the antibody that triggers an allergic reaction. In the past, specific IgE was measured using radioactivity, but modern tests don’t use this method.²¹ Current tests, such as those using fluorescent (FEIA) detection, can be more effective.

• RAST is less sensitive and less specific. According to the National Institutes of Health Guidelines for the Diagnosis and Management of Food Allergy, immunofluorescent in vitro IgE assays (e.g., modern specific IgE blood tests) are superior in both sensitivity and specificity to tests using the older RAST method.²⁰ In other words, modern-day specific IgE (FEIA) blood tests for allergies are more accurate than RAST.

If you were tested as a child or perhaps even as few as two years ago, your allergies today may be different than in the past. Testing may help your provider develop a current diagnosis.

• Consider testing every two years. According to the American College of Allergy, Asthma, and Immunology, there’s no limit to the frequency of testing. However, two years is a reasonable amount of time to elapse between allergy tests, particularly if you’ve been on an allergy medication and allergen-avoidance plan for two years and your symptoms have returned or worsened.¹⁸

• Allergies are not static. Studies show people can gain new allergies over time. Because you knew what you were sensitized to a couple of years ago doesn’t mean you or your provider knows everything you’re allergic to today. ¹⁸