Food Allergy

Dos and Don’ts Prior Food Allergy Testing

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Updated on January 24, 2024

Let’s assume you notice your body behaving strangely when you eat a particular item, and you’re not sure why, even though you don’t have any food allergy. So, my dear friend, the only answer is to undergo allergy testing to get to the bottom of what’s wrong with your body. 

Your body may react in one of two ways: skin rashes or belly aches. However, symptoms can swiftly escalate into a potentially fatal allergic reaction known as anaphylaxis or anaphylactic shock. Anaphylaxis is a medical emergency that can damage your entire body, including your breathing ability. Furthermore, predicting when an allergic reaction may progress from mild to severe is impossible.

In this article, we will walk you through all there is to know about taking an allergy test, including what you should do before and avoid. Of course, we’ll tackle all of your common questions. Remember that the end aim is to figure out what is giving you discomfort and to understand your body better; after all, your health is essential.

Food Allergy

What Is the Function of Food Allergy Testing?

Food allergy testing detects whether you are allergic to a specific food or have outgrown a recognised food allergy. As a result, they can help you determine if you have a real allergy or food sensitivity or intolerance.

Many people mix food allergy tests with food intolerance tests in the allergy world. There are significant differences between the two; let us explain more. Food intolerance testing does not screen for food allergies, which means that while food intolerances may have similar symptoms, they are mainly related to the digestive system and aren’t as dangerous as food allergies. Instead, the symptoms of food intolerance include nausea, stomach discomfort, bloating, and diarrhoea. 

It is best to keep an eye out if you detect any of the following symptoms. Symptoms appear within minutes to hours of exposure to specific foods. Symptoms that may affect your digestion, breathing, or skin include:

  • Coughing
  •  Diarrhoea
  •  Nausea and vomiting
  •  Red, itchy skin or a rash
  •  Skin reactions, such as hives or itching.
  •  Stomach pain
  •  Stuffy, itchy, or runny nose
  •  Tingling in the mouth

Suppose you have had anaphylactic symptoms. Symptoms of this potentially fatal reaction might occur minutes to hours after exposure to particular foods. Among the symptoms are:

  • Dizziness
  •  Fainting
  •  Rapid heart rate
  •  Swelling of the tongue or throat
  •  Trouble breathing

What Is the Difference Between Food Allergy Testing and Food Intolerance Testing?

Some people confuse food allergy testing and food intolerance testing, but they are different. Let us break it down and explain more. First, let’s talk about food allergies and intolerances

Food allergies are severe and potentially fatal, causing extreme swelling, rashes, vomiting, and other symptoms. If you have a food allergy, you will need professional medical help and support to manage any reactions.

Food intolerances vary significantly and affect many of us with symptoms that we commonly ignore. Bloating, IBS, digestive issues, fatigue, headaches, moodiness, and skin reactions (e.g., acne, eczema) are all symptoms of food intolerance. Food intolerance reactions are rarely life-threatening but can cause discomfort and disrupt daily living. Food allergies are far less common than food intolerances. Once identified, food intolerances are best treated by lifestyle adjustments guided by a nutritional specialist to ensure your body receives nourishment. 

A variety of reasons can contribute to food intolerance, including:

  • The absence of an enzyme essential for complete food digestion. A common example is lactose intolerance.
  •  IBS is an abbreviation for irritable bowel syndrome. Cramps, constipation, and diarrhoea are all signs of this chronic condition.
  •  Sensitivity to food additives. Food additives such as sulfites used to preserve dried fruit, canned goods, and wine can cause asthma attacks in some people who are allergic to them.

Now that we’ve discussed the difference between food allergies and intolerance let’s look at how each test works.

Food Allergy

What Is the Procedure for Testing for Food Intolerance?

A food sensitivity also known as an intolerance test, is relatively easy, requiring only a few drops of blood as a sample. The level of IgG antibodies identified in the blood for each type of meal is then tested in a lab. Thus, your specific dietary IgG reactivity levels can be determined.

What Is the Procedure for Testing for Food Allergy?

An allergy specialist will want to hear about your family’s medical history and your own, including any previous allergies. A physical examination is usually performed before allergy testing. The specialist will then conduct one or more food allergy tests. There are four types of allergy tests, each with its own set of risks. As a result, it is advisable to consult with the doctor to determine whether the tests are proper for you. The most typical tests are as follows:

  • A skin prick test 
  •  An allergy blood test 
  •  An oral food challenge test 
  •  A food-elimination diet

4 Different Types of Allergy Tests

Food allergies are notoriously tricky to diagnose; therefore, you may need multiple tests or procedures. Skin and blood tests can be inconclusive at times. Having passed both exams allows the doctors to fill in the blanks when they require more information. So, let’s review the four food tests you can take one or two of.

Skin Prick Test (SPT)

If you are terrified of needles, you will not enjoy this type of test. Skin prick testing, sometimes known as a scratch test or puncture test, can help confirm several common types of food allergies. For example, a Skin Prick Test for an egg allergy can be performed by applying a little drop of egg proteins to your skin. The area will then be delicately punctured or scratched with a needle through the drop by your doctor. Redness, swelling, and itching will occur if you are allergic to the substance.

An elevated, spherical zone that resembles a hive may be visible. This is usually seen within 15 minutes of arriving at the testing area. The more severe your reaction, the more likely you are allergic to the allergen. 

A positive test, however, does not imply that you are allergic to the substance. It also cannot predict whether or not you will have a severe allergic reaction. A negative skin test, on the other hand, usually means you are not allergic. 

Skin Prick Testing (SPT) is the most common testing method for real food allergies. It is safe for most patients, including newborns, and can be done during a routine clinic visit. The test results are provided immediately after the test, allowing you to discuss them with your doctor during the same visit. Just be aware if you have sensitive skin, as some people may have false positive skin test results. This could occur if a patient has an allergic skin disorder and develops redness due to the condition.

Specific IgE Blood Test

We will use scientific terminology, but don’t worry; we will keep it simple. A Specific IgE blood test examines your blood for immunoglobulin E (IgE) antibodies. Antibodies are proteins that your immune system generates in response to allergens or other substances that could be harmful such as viruses or bacteria. Your body creates IgE antibodies when you have an allergy. Even if a trigger chemical is entirely safe, an immune response of this type can occur.

Another needle situation is because this test is performed by simple blood work and is usually chosen because several allergies can be detected with a single blood sample. Your doctor obtains a blood sample, and the lab then adds the allergen and the number of antibodies your blood produces that protect against the allergens is determined.

A Specific IgE Blood Test, or RAST or ImmunoCAP testing, does not always produce accurate results. False positive outcomes are common with many diagnostic tests. Specific IgE blood tests will produce false positive results more than half the time. In other words, even if you test positive for a food allergy, you may not always have allergy symptoms when eating that item.

Blood tests are suitable for patients with sensitive skin disorders such as eczema, for those using medications such as antihistamines that may interfere with a skin prick test, and for those, such as young children, who cannot have a skin allergy test for whatever reason.

Oral Food Challenge (OFC) Test

The Oral Food Challenge takes place at the doctor’s office. Because of the likelihood of a life-threatening reaction or anaphylaxis, the test can be supervised by your doctor, who is usually an allergist.

During an oral food challenge test, an allergist and their expert team feed you a portion of food to see whether you have an allergic reaction, monitor your reaction, and are prepared to administer emergency treatment if necessary. This test can take 3-6 hours under medical supervision. The test validates your allergies and tells you whether you should avoid the item.

The Oral Food Challenge (OFC) Test is generally known to be the gold standard for diagnosing food allergies because it delivers the most accurate results. It is the most precise food allergy test. This test is typically conducted following a skin prick or blood test. It is usually recommended if you have tested positive for food but have never reacted to it or if your skin and blood tests indicate enough improvement to support testing.

Patch Test

Patch testing is used to help diagnose suspected allergies and determine which allergen is causing skin irritation, contact dermatitis, or delayed skin responses. A reaction to an allergenic substance may not show for several days after exposure. A small amount of allergen extract is applied to your skin, usually your back, and wrapped to confirm a suspected allergy. After 48 to 96 hours, the reactivity at the allergen location is routinely evaluated.

When testing for food allergies, actual food is used to see how your body reacts to its presence. These foods are often chosen based on your diet, medical history of reactions, and previous skin testing findings. It should be noted that during a patch test, your skin may be exposed to twenty to thirty different chemical extracts. Suppose you are allergic to any of these compounds. In that case, you will experience a regional rash or what appears to be an itchy bump on the spot.

During your appointment, your doctor will then apply a special tape with a panel of food extracts to your back and schedule a follow-up appointment for you 48 to 96 hours later to remove the panel and perform a physical examination to assess your skin’s reaction. The patch test is used to screen for food allergies. Still, it can also be used to test for latex, medications, fragrances, preservatives, metals, hair colours, and resins. 

What You Shouldn’t Do Prior to an Allergy Test

Food Allergy

Of course, if you’re going through the allergy test cycle, you’ll want to be sure the results are accurate, so there are some items you should avoid before an allergy test. Of course, please consult your doctor or allergist to see what they recommend. Still, they will almost certainly suggest putting off some of these. 

Each food test is different, so here is a list of what to avoid before each one, depending on your test. An important note is that it is always best to consult your doctor first. 

Foods and Medications to Avoid Before a Skin Prick Test (SPT)

It is best to avoid any food or drink containing alcohol, chocolate, coffee, or other caffeine products if you are taking the skin prick test.

Medications can interfere with results, so list all prescription and over-the-counter medications you’re taking before scheduling a skin test. Some of these medications may suppress allergic reactions, preventing skin testing from being diagnosed accurately.

  • Allergy medicines (both prescription and over-the-counter)
  •  Tricyclic antidepressants
  •  Several heartburn medications
  •  Asthma treatment Xolair

Foods and Medications to Avoid Before a Specific IgE Blood Test

The short answer to whether you should avoid particular foods before your Specific IgE Blood Test is no. You do not need to do anything unusual to prepare for an allergy blood test. However, you must consult your doctor if you need to fast before the test.

You can double-check with your doctor about the medication. Before your Specific IgE lab test, phone your doctor’s office and ensure there is no need for fasting, no foods to avoid, and no medications to discontinue, including Zyrtec, before your blood test at the lab.

Foods and Medications to Avoid Before an Oral Food Challenge (OFC) Test

You should consult your doctor about any special instructions they may have for your test. You can eat a small meal on the day of the challenge, but it should be something you’ve eaten before that has not caused a negative reaction. It would be best to consume only 1-2 hours before your food challenge. 

Foods and Medications to Avoid Before a Patch Test

It is best to consult your doctor to determine what you should avoid. However, like with the skin prick test, you should avoid any food or drink containing alcohol, chocolate, coffee, or other caffeine products because they may impact the results. 

Certain medications must be stopped before your consultation. Your allergist or food allergy nurse will review everything you need to know in detail so you know which medications to stop and when. However, here are some to get you started: 

  • Oral steroids (such as prednisone, methotrexate, and cyclosporine) 
  •  Immunosuppressive medications
  •  Notify your doctor if you have gotten allergy shots or cortisone injections.
  •  Avoid sun exposure 
  •  Topical medications (creams and ointments) on the area of your back where the patches will be applied for at least a week before your visit. 

What You Can Do to Prepare for an Allergy Test

Life is simple, and just because you’re getting ready for an allergy test doesn’t mean you shouldn’t enjoy it to the fullest. Always see your doctor or allergist to confirm what you must avoid. Still, otherwise, you can normally go about your daily life. Don’t panic; you continue to do activities people are curious about before allergy testing. Just remember that the decision you’re making is for the best.

Food Allergy

Avoid the Sun

Suppose you are going to take the skin test. In that case, it is recommended to avoid sun exposure, merely to avoid sunburning, as this will make the test painful and make reading the results difficult.

Bring Entertainment

While the skin test is quick, the session can last several hours. Bring something to keep you occupied. If you’re lucky, some allergists will provide you with films to watch during your appointment.


Some tests require eating, while others may demand you to fast for an hour or two. Consult your doctor about the regulations you must follow and, based on that, have a healthy lunch rather than staying on an empty stomach all day. 

Avoid Taking Medication

Before your test, your allergist should provide you with a list of things you should and should not take. Most antihistamine-containing medications must be avoided for at least seven days before your test. This is because the tester must observe what you react to when tested. Antihistamines will block the majority of allergic reactions.

Suppose you take medications for another chronic disease, such as heart disease or breathing treatments for your chest or nose. In that case, you should continue to do so. You can generally restart all drugs after your skin test. Consult your allergist for particular medication advice regarding testing.


Food Allergy

Last but not least, whichever test you are doing is a pretty simple operation; you don’t need to panic unless you are frightened of needles, but just know you will be surrounded by people who will take good care of you and ensure you are comfortable. Just keep in mind that this is all for your health’s sake

Final Thoughts!

We hope this information was helpful and persuaded you to take the test and stop disregarding your body’s warning signs. After all, your health should be your priority.

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