Preparing for an Allergy Test: What You Should Know

Dos and don’ts you should consider before getting an allergy test

Allergies are one of the most common health conditions – in the UK, allergic disease affects about one in three of the population.¹ But identifying exactly what is causing your allergies may not be so straightforward, and only a doctor 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.

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.

The most common 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. 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. They’ll be able to determine the source of your allergy, and develop a customised plan to help get you some relief. 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 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 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.

Patch test

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 surgery, your doctor will check to see if there’s been any reaction, such as a rash.

Challenge test

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 with a medical professional 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 not to 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 to see what they recommend, but they’ll likely advise holding off on some of these.

Antihistamines

Perhaps the most important part of preparing for allergy testing is letting your doctor know about all medications and supplements you’re taking, even over-the-counter ones. If you’re taking an antihistamine, like Allevia, 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.

Certain antacids

Some antacids (tablets for heartburn or indigestion) 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!

Beta-blockers

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.

Tricyclic antidepressants

Medications known as tricyclic antidepressants, such as amitriptyline and lofepamine, 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.

Fragrances

Even if you don’t have an allergy to certain ingredients in fragrances, keep in mind that other patients in the doctor's surgery 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 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.

Shower

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.)

Regular diet

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, doctor's surgery permitting.

How Do You Read Allergy Test Results?

Only your doctor 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.

Allevia 120mg tablets contain fexofenadine. For the symptomatic relief of allergic rhinitis. Always read the label.

MAT-XU-2304442 V1.0 (September 2023)

References

Allergy: the unmet need. BSACI, 2003. https://www.bsaci.org/wp-content/uploads/2020/02/allergy_the_unmet_need.pdf Last accessed September 2023

This article is not a substitute for medical advice. Allevia should be used as directed according to the product label. If you suspect that you have allergies, consult with your doctor or pharmacist. Only they can make a proper diagnosis.