Preparing for an Allergy Test: What You Should Know
Dos and don’ts you should consider.
Allergies are one of the most common health conditions, with 5.2 million children and 19.2 million adults in the U.S. alone experiencing hayfever,1 and a whopping 20% of people coming down with hives.2 But identifying exactly what’s causing your allergies may not be so straightforward, and only a doctor or allergist can truly diagnose what’s setting them off. Before an allergy test is taken, however, it’s important to know the right way to prep for allergy testing to be sure you’ll get the most accurate results possible.
Below, learn all about how to prepare for an allergy test—including a breakdown of each type, what to avoid before your test, and what to expect afterwards.
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Hallmark allergy symptoms—associated with allergic rhinitis and other allergies like food-borne ones—such as itchy eyes, a runny nose, and hives, as well as sneezing, coughing, or a scratchy throat, are the result of your body’s immune system attacking what it perceives as a foreign substance. Allergies are the sixth leading cause of chronic illness in Americans—and one of the most common health issues among kids.1 Despite their prevalence, allergies are often overlooked, with many people choosing to just power through them rather than get proper treatment. But trying your best to ignore your allergies isn’t advisable. Left unchecked, allergies can be more than just an annoyance. They can negatively impact your quality of life.
Instead, book an appointment with your doctor or an allergist. They’ll be able to determine the source of your allergy, and develop a customized plan to help get you some relief. Then, read on to discover what you should know before allergy testing, like the different types of diagnostics, how to prepare for an allergy test, and things you should and shouldn’t do. That way, there’ll be minimal surprises and you’ll know what to expect at an allergy test.
Types of Allergy Tests
Depending on your symptoms, your doctor or allergist will try to narrow down possible allergy culprits using one or more of the following tests.
Skin prick or scratch test
One of the most common allergy tests is the skin prick test for allergens, which commonly checks for allergies to airborne particles like pollen and animal dander. First, your doctor or allergist will prick the skin on your back or forearm with a thin needle, or they’ll scratch it with a sterile device to lightly puncture it. They’ll then expose it to anywhere from 10 to 50 potential allergens, depending on which ones they suspect, to see what you might have a reaction to. It usually takes about 15 minutes and, if you have an allergy to one or more of the substances, your skin will become red, with a possible rash or raised spots known as “wheals.”
Intradermal skin test
If the results of a skin prick test for allergens are inconclusive, or if they come up negative and an allergy is still suspected, you may be given an intradermal skin test. Rather than just exposing punctured or lightly scratched skin to a potential allergen, a small amount of the suspected substances are injected into the top layer of your skin to see if a reaction occurs. In addition to airborne particles, this test can also check for allergies to certain insect stings or medications.
When the cause of your allergy is thought to be a material coming into contact with your skin, like wool or nickel, it’s known as “contact dermatitis.” A patch test involves placing a few drops of liquified allergens onto your arm and covering it with a bandage for two to four days. When you return to the office, your doctor or allergist will check to see if there’s been any reaction, such as a rash.
For suspected food and/or drug allergies, your provider will quite literally challenge your body by having you ingest a small amount of the potential allergen, like milk or nuts, to see if it causes a reaction. It may sound simple enough, but definitely don’t try this one at home. This test absolutely has to be done in-office in case you have a serious reaction such as anaphylaxis, which requires immediate medical attention.
Immunoglobulin E (IgE) blood test
As the name implies, for this one, a sample of your blood will be sent to a lab and mixed with potential allergens. There, the level of IgE antibodies—which are produced during an allergic reaction—will be checked. Though it seems like this might be the most accurate way to diagnose an allergy, IgE blood tests actually have a higher rate of false-positives—that’s why they’re not usually the initial go-to.
What You Can’t Do Before an Allergy Test
In order to help ensure the accuracy of your results, there are certain things you should avoid before an allergy test. Of course, speak with your doctor or allergist to see what they recommend, but they’ll likely advise holding off on some of these.
Perhaps the most important part of preparing for allergy testing is letting your doctor or allergist know about all medications and supplements you’re taking, even over-the-counter ones. If you’re taking an antihistamine, like Allegra, you should stop taking it three days to a week before your allergy test, so it doesn’t subdue your body’s response to the allergens in question. So, be sure to check with your provider at least a week before allergy testing to see how long they recommend refraining.
Some antacids also contain a form of antihistamine, so they should be avoided for at least a day prior to when you embark on an allergy test. Contact your provider for a complete list and their recommendation on timing. (You may want to put a pause on any acidic, heavy, or spicy foods in the meantime too.)
If you take a beta-blocker, like timolol or metoprolol, which are used for high blood pressure, a heart condition, anxiety, migraines, and glaucoma, get permission from the doctor who prescribed it before temporarily discontinuing it. In the event that you have a serious reaction to an allergen you’re exposed to, a beta-blocker can slow your body’s response to an emergency injection called epinephrine.
Medications known as tricyclic antidepressants, such as amitriptyline and doxepin, can also suppress your body’s immune response for a week or two and interfere with the results of an allergy test. Ask your prescribing doctor how you should proceed temporarily going off your regimen.
Even if you don’t have an allergy to certain ingredients in fragrances, keep in mind that other patients in the office may. Out of courtesy, put down the hair spray, perfume, or scented lotion for the day.
What You Can Do Before an Allergy Test
Just because you’re preparing for an allergy test, that doesn't mean you should be discouraged from living life to the fullest. Always check with your doctor or allergist to confirm what you definitely should avoid, but, otherwise, you can usually go about your daily business. And, rest assured, you can still continue with some of these things people wonder about before allergy testing.
Steroid nasal sprays
It’s typically okay to continue using a steroid nasal spray, but always confirm with your provider prior to the allergy test.
While you’ll want to avoid any strongly-scented lotions or colognes for the sake of the other patients, it’s fine to shower before an allergy test, as well as wear deodorant for allergy testing. (Some might say this is also for the other patients.)
Aside from avoiding suspected food allergens—and potentially irritating food if you go off of an antacid—in preparation for allergy testing, there’s no need to change anything in your diet. You can even bring something to drink and snack on to your appointment, office permitting.
How Do You Read Allergy Test Results?
Only your doctor or allergist can accurately read the results of your allergy test. However, keep in mind that skin tests will show visible results, and blood tests (if given) will show higher than normal levels of IgE antibodies. And, you’ll definitely notice if you have a reaction to ingesting a food that you’re allergic to during a challenge test. After that, your provider will come up with a treatment plan specifically for the type and severity of allergy you have. Be sure to ask them any questions you may have and keep an open line of communication to update them on your progress and any other reactions you may experience.
Allegra® is here to help.
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*Allegra is indicated to relieve sneezing, runny nose, itchy, watery eyes, and an itchy nose and throat. Allegra-D is indicated to releive sneezing, runny nose, itchy, watery eyes, itchy nose or throat, nasal congestion, sinus pressure, and reduces swelling of the nasal passages.
†Among single-ingredient branded OTC oral antihistamines and OTC multi-ingredient allergy & decongestant brands.