How Accurate Are Allergy Tests? Plus Some to Avoid at All Costs

Diagnosing allergies can be difficult. It can require several steps, including specialized tests, a thorough history of symptoms, and a physical exam. Getting a correct diagnosis can take several months, and the process can be slow, frustrating, and anxiety provoking.

To confuse matters further, there are an increasing number of mail-order tests available that claim to diagnose allergies. It’s no surprise that many people are drawn to these tests as a quick way to get answers about their allergies. 

But most of the allergy tests you’ve seen marketed are at best inaccurate. At worst, they can make you take drastic actions that aren’t good for your health. 

When it comes to allergy tests, if it sounds too good to be true, it probably is. With this in mind, here are the facts about allergies, how to accurately diagnose them, and which tests you should absolutely avoid. 

What are allergies?

Allergies are an abnormal reaction in the body to an allergen — a generally harmless substance. There are many different types of allergens, including: 

• Food

• Insects

• Mold

• Pet dander

• Pollen

When someone with an allergy comes across an allergen, their immune system overreacts and tells their cells to release chemicals, causing allergy symptoms (an allergic reaction). Allergy symptoms can happen anywhere in the body, but common places include the: 

• Gut

• Eyes

• Nose

• Throat

• Lungs

• Skin

Allergic reactions differ from person to person. Symptoms can vary. Some people might only have mild symptoms. Other people may have anaphylaxis — a life-threatening reaction. Some examples of common mild symptoms include swelling, sinus pressure, congestion, and skin rash. People may also have itchy eyes, nose, or mouth.

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• Looking for the best allergy medications? Read our guide to the most effective over-the-counter (OTC) allergy medicines — from pills to nasal sprays.

How do you test for allergies?

Here’s the important thing to know: There’s no single test for allergies, and no test is 100% accurate. 

The first step to testing for allergies is that you need to have allergy symptoms. That means you have symptoms of allergy when you are exposed to a certain allergen. For example, your eyes itch around cats. 

The second step is to check for a positive result on one or more of these allergy tests.

1. Skin-prick test

This is the most commonly used test for allergies. It checks to see if your body has made immunoglobin E (IgE) antibodies against a specific allergen, like dust mites or a food. A tiny needle injects small amounts of potential allergen into the skin. Then you wait to see if you develop a reaction (a small itchy skin bump at the site of the injection). 

If you do develop a reaction, it doesn’t necessarily mean that you have an allergy. You can have something called a “false positive” result. 

But, if you don’t develop a reaction, that’s a pretty accurate negative result. It means it’s likely you don’t have an allergy to that substance. 

2. Blood test

Also called the radioallergosorbent test (RAST), this test looks for IgE antibodies in the blood. Like the skin-prick test, a positive test doesn’t necessarily mean you have an allergy. But a negative test means you probably don’t have an allergy. 

3. Allergen challenge test

This is when you inhale or consume a small amount of an allergen to see if you get allergy symptoms. This is one of the most accurate ways to see if you have an allergy. But it also has a risk of severe side effects (like anaphylaxis). Allergen challenge tests have to take place in a controlled setting with trained healthcare professionals. 

4. Atopy patch testing

This is a test you do for a suspected food allergy, when skin-prick and blood tests are negative. Unlike the other tests, this type of allergy test doesn’t involve IgE antibodies. Small patches with different food extracts are taped to your back and left for up to 3 days. A positive result is an itchy skin bump.

Interpreting allergy test results

Knowing the pattern of your symptoms can help make sense of your allergy test results. For example, if your seasonal allergy symptoms match with a positive test for ragweed pollen, a common cause of hay fever. But if you have these symptoms and you test positive for a food allergy, that’s less likely to be accurate.

It’s worth remembering that some people may be sensitive to foods but not have a true allergy. A food sensitivity can cause some of the same symptoms as a food allergy. But it’s not caused by an immune system reaction, so your allergy tests will be negative.

Allergy tests to avoid

Many tests, including at-home allergy tests, claim to diagnose allergies. Some are available online, by mail order. Others are offered by “special” practitioners. It can be tempting to pay for these tests in the hope of getting quick answers. 

But unfortunately, there’s no scientific evidence behind many of these tests. In fact, professional allergy organizations, like the Asthma and Allergy Foundation of America (AAFA), advise people to avoid them.

1. Hair testing

What it is: Hair testing claims to use bioresonance technology to examine hair samples. In theory, certain patterns of electromagnetic resonance from a hair sample can tell you if you have food or environmental allergies.

The reality: There’s no scientific evidence that hair is involved in allergic reactions. Hair may be tested for toxic levels of heavy metals (like too much lead exposure) or nutritional deficiencies (like not enough zinc). But these heavy metals have nothing to do with food or environmental allergies. In summary, hair testing can’t diagnose allergies. 

2. IgG food intolerance test

What it is: This test looks for immunoglobin G (IgG) antibodies in the blood. In theory, the presence of these antibodies can show whether your immune system is sensitive (allergic) to certain foods.

The reality: IgG antibodies are also found in people without food allergies or intolerances. Having these antibodies doesn’t mean you’re sensitive to these foods. It just means your immune system has been exposed to them. Checking for these antibodies can’t accurately diagnose a food allergy or a food intolerance. In other words, a positive IgG food intolerance test doesn’t mean you have a food allergy or intolerance.

3. Vega machine test

What it is: This electroacupuncture machine measures electrical resistance across your skin at various points. These measurements supposedly provide information about food and environmental allergies.

The reality: There’s no scientific evidence that Vega measurements are related to allergies. Results are the same in people who do and do not have allergies. Experts don’t recommend this test as an accurate way of diagnosing allergies.

4. Applied kinesiology

What it is: In this test, a person holds a suspected allergen in their hands or mouth. A practitioner then assesses muscle weakness. This practice is supposed to figure out whether an allergy is present.

The reality: There’s no scientific evidence that allergies cause muscle weakness. Results may be influenced by the practitioner. It’s not a useful tool for diagnosing allergies.

5. Cytotoxic tests (ALCAT, FACT, and Bryan’s test)

What it is: In this test, a blood sample is mixed with a suspected allergen. The white blood cells are then monitored for injury. In theory, cell injury demonstrates whether or not there’s an allergy.

The reality: There’s no scientific evidence to support this practice. The reaction of white blood cells is unchanged whether or not you have an allergy.

6. Nambudripad’s Allergy Elimination Techniques (NAET)

What it is: This system of diagnosing and treating allergies is based on the belief that allergies are caused by an “energy blockade” and can be treated with acupuncture.

The reality: There are no published studies that say these techniques can accurately identify or treat allergies.

7. Pulse test

What it is: In this test, a practitioner measures your pulse twice, once before you’re exposed to an allergen and then again 15 minutes after exposure. In theory, your pulse will change if you are allergic to the substance.

The reality: There’s no scientific evidence that there’s a reliable connection between increased pulse and allergies.

Why you should avoid unproven allergy tests

Unproven allergy testing can have serious consequences. These tests often cost a lot of money, and health insurance usually doesn’t cover them. Plus, they can lead to false hopes and expectations. They may even delay correct diagnosis and treatment.

Believing you’re allergic to something when you’re not can impact your quality of life — and your health. It may lead you to make unnecessary lifestyle changes, like excluding certain food groups or restricting foods and social situations that you enjoy. 

Why trust our experts?

Written by:

Sarah Gupta, MD

Sarah Gupta, MD, is a licensed physician with a special interest in mental health, sex and gender, eating disorders, and the human microbiome. She is currently board certified by the American Board of Psychiatry and Neurology.

Edited by:

Sophie Vergnaud, MD

Sophie Vergnaud, MD, is the Senior Medical Director for GoodRx Health. An experienced and dedicated pulmonologist and hospitalist, she spent a decade practicing and teaching clinical medicine at academic hospitals throughout London before transitioning to a career in health education and health technology.

Reviewed by:

Maria Robinson, MD, MBA

Maria Robinson, MD, MBA, is a board-certified dermatologist and dermatopathologist who has practiced dermatology and dermatopathology for over 10 years across private practice, academic, and telehealth settings. She is a fellow of the American Academy of Dermatology and the American Society of Dermatopathology.

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