I. Introduction

While awareness of food allergies may be rising, so are the number of people seeking medical attention for urgent allergic reaction issues. In fact, from 2007 through 2016, the number of medical procedures performed because someone was in anaphylactic shock due to a food allergy almost quadrupled. In a few cases, discovering that you have a specific food allergy may allow you to seek a cure or remedy. Most of the time, however, you do have to learn to live with your allergy, and knowing about and understanding it is the first step toward doing so in a positive way.

Food allergy tests help doctors determine what you might be allergic to. This guide provides comprehensive information about how food allergy tests work and some basics about common food allergies and potential treatments.

II. Overview of Food Allergy Tests

Why should I get tested?

Not everyone needs a food allergy test. According to Choosing Wisely, an educational initiative of the American Board of Internal Medicine Foundation, if you get tested without guidance from a doctor and a doctor’s exam, the time and effort can be a waste. It could also result in needless false positive results — indicating you have an allergy to a food that you’re only intolerant of or don’t have any sensitivity to.

Choosing Wisely goes on to point out that allergy skin tests can cost up to $300 a pop while blood tests can be as expensive as $1,000. While you certainly want to get tests if they’re medically necessary, the expense makes these tests prohibitive for appeasing simple curiosity.

When should I get tested?

If you experience potential food allergy issues of a nonurgent manner, such as seeming intolerance that causes stomach pains or a rash, try to determine which food caused the problem. Keep it out of your diet to see if you find some relief. In minor cases, you can also use over-the-counter products and medications to treat the issue. For example, someone with mild dairy sensitivity may take a product, such as Lactaid, before eating mac and cheese.

But if problems persist or you can’t get relief from these measures, you may want to talk to your doctor about getting tested for food allergies. Medical professionals might also run tests in cases where someone has experienced an emergency-level reaction to food but isn’t exactly sure what caused it.

Information published by the U.S. National Library of Medicine does point out that some people may want to talk to their medical providers about proactive testing. If you have a known risk of a severe food allergy, getting comprehensively tested can help you avoid the potential of a dangerous exposure in the future. Risk factors include:

  • Genetics — if someone in your family has a food allergy, you’re more at risk for having one
  • Asthma
  • Allergies to other foods — food allergies sometimes run in packs
  • Other allergies — in fact, all allergies have the potential to run in packs, so your seasonal hay fever could put you at greater risk

What is required for the test?

You can buy some at-home food allergy tests or seek out free screening opportunities offered by drug stores. But the ABIM Foundation notes that the results from these tests can be unreliable or misleading. The most accurate food allergy testing is conducted by a doctor or allergist. They will provide everything needed for the test, which may include small samples of the potential allergen and the tools required to take blood samples (in the case of a blood test for food allergies).

What do I need to do to prepare for the test?

No preparations are needed for these tests.

III. The Basics of Food Allergies

Food allergies are often confused with food intolerances. Harvard Health Publishing, a site from Harvard Medical School, discusses the differences between intolerances and allergies.

Intolerances are sensitivities that typically occur because you don’t have an enzyme — or enough of it — to properly digest a certain type of food. You may be able to eat a certain amount of the food before this becomes an issue. The more you eat, though, the greater your distress can become. The distress in cases of food intolerance is typically digestive, which means stomach aches, gas, bloating, diarrhea, or vomiting.

In the case of allergies, however, your body is wired incorrectly. It actually sees the food you’re allergic to the same way it might see a germ, so it tries to fight off this food via an immune system response. That leads to rashes, hives, throwing up, or diarrhea. Extreme cases can lead to anaphylaxis. That’s when your reaction is so severe it causes swelling of the airway or tongue, fainting, or other related symptoms. If left untreated, some cases of anaphylaxis can lead to death.

According to the FDA, there are more than 160 foods that could lead to an allergic reaction. However, by legal definition, eight main categories of food are identified, and those cover 90% of the potential allergy-inducers. The categories include: eggs, milk, shellfish, fish, peanuts, tree nuts, soybeans, and wheat.

IV. How a Food Allergy Test Works

The basic idea of a food allergy test is that you introduce the food into the body in a very small and controlled amount and look for a reaction. When performed by an allergist or doctor, these tests can take on three basic formats.

Oral Challenge Tests

This type of test occurs by introducing a very small amount of the food into the body orally. Often the food is in a capsule. Then a clinical professional observes the person closely to see if they have a reaction. They are also there to provide treatment if a serious reaction occurs.

Skin Prick Tests

This may be the most well-known allergy test in regular circles because it’s the one typically demonstrated in television shows or movies when allergies are being addressed. Basically, skin prick allergy tests follow a standard procedure.

  • The testing clinician puts a small amount of the substance on your skin. Usually, they put it on your forearm or your back.
  • They prick the skin at that site with a small needle. This causes a tiny bit of the food particles to enter your body.
  • The clinician looks for a skin reaction. A raised, red bump that itches typically indicates that you have an allergy to that substance.

Blood Tests

Medical professionals can test for a certain type of antibody to see if you are allergic to something you were exposed to. Your body typically only produces this antibody if you were allergic to the substance. Again, the tests are controlled, so you’re exposed to the food in a small dose before a blood draw is performed.

V. Treatment for Food Allergies

The prevailing wisdom is that true food allergies have no cure. The “cure” is to not ingest the food or substance your body reacts to. That can mean changing your diet, reading labels, and asking about ingredients when you order in a restaurant.

Because even the most careful person may not have 100% control over all the food they eat, though, doctors may prescribe an EpiPen or equivalent. This is often the case when someone is at risk for a severe food allergy reaction. These devices let you quickly self-administer medication (or have someone else administer it) to stop or slow allergic reactions that could be life-threatening.

According to Stony Brooke Medicine, some research is demonstrating positive results with food immunotherapy. This involves introducing the food in increasingly large doses over time as your body develops an immunity to it and doesn’t launch the adverse reaction. It could be that for some food allergies, these types of measures could foster cures for certain individuals. Because of the risks involved, however, you should avoid testing these theories without the guidance of a healthcare professional.

VI. Frequently Asked Questions

Are food allergy tests accurate?

According to FARE, around half of all skin prick tests result in a false positive result. That’s why it’s important to undergo this type of testing with a professional. He or she is able to accurately read tests and draw conclusions from the big picture rather than a single skin prick test.

What is a false positive?

A false positive is when a test appears to give a positive result, but it’s inaccurate. In the case of food allergy testing, if the test shows you’re allergic to a food and you’re not, it’s a false positive. This is a risk with skin prick testing, as the reading of the site is subjective. In a few rare instances, you might also have a reaction at the site for reasons other than a food allergy.

Can you eat before an allergy test?

You should follow your medical provider’s instructions to prepare for an allergy test. In most cases, you can eat before a food allergy tests. It’s a good idea to eat only foods you’re familiar with and know you won’t have a reaction to. This can reduce the chances of a false positive on your test.

Are food allergy tests covered by insurance?

Food allergy tests conducted by a medical practitioner may be covered by your insurance plan. You can work with your doctor’s office to verify insurance benefits to make sure of coverage before you proceed if you’re unsure. You or your doctor’s office can call your insurance company and ask whether the procedure codes related to the testing are covered. The insurance company can usually provide information about copays and whether a special referral or authorization is required before the tests are administered.

Do food allergy tests hurt?

Skin prick tests worry some people because the idea sounds painful. But another name for this test is the superficial scratch test, which might seem less frightening. Typically, these tests don’t really hurt. Some people may not feel entirely comfortable throughout the test, especially if many substances are being checked, but most don’t feel any serious pain. The American College of Allergy, Asthma and Immunology does note that some people may feel very minor pain during the test if they are especially sensitive to needle pricks. The area around the test may also itch or be uncomfortable for a while if an allergy is present.

How long does a food allergy test take?

It usually takes around 20 minutes from the time of the skin prick for a reaction to show up in a way that’s conclusive. When you factor in checking in at the doctor’s office, waiting for the test, being prepared for the test, and any discussion afterward, an appointment for food allergy tests could take from one to three hours.