Interpreting Allergy Blood Test Results: Procedure and Diagnosis

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How do you read allergy test results?

Allergy test results are read by comparing the size of the skin reaction to each allergen. Larger reactions indicate a stronger allergy. The allergist will then interpret these results, taking into account your symptoms and medical history, to diagnose any specific allergies.

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What Is an Allergy Test?

An allergy test is a diagnostic procedure used to identify specific allergens causing an individual's allergic reactions. It can be performed using various methods such as skin tests or blood tests. The type of test chosen often depends on the individual's health condition and the nature of the suspected allergens.

Overview of Allergy Test Results

Examining your allergy test results can give you insight into the allergens causing your symptoms. The results will indicate whether you have a positive or negative reaction to each tested allergen. A positive result suggests you may be allergic to a particular substance, while a negative result indicates no detected allergy. However, the severity of your allergic reaction can't be determined solely based on the size of the reaction on the test.

Details of the Allergy Test Procedure

The allergy test procedure varies depending on the type of test. For a skin prick test, small amounts of allergens are pricked into the skin and observed for a reaction. Alternatively, an allergy blood test involves drawing blood to measure the level of specific antibodies produced in response to allergens. Results from allergy tests are typically available within a few hours to several days, depending on the test type. It's crucial to discuss with your healthcare provider which test is most suitable for you.

Why Are Allergy Blood Tests Done?

Allergy blood tests are performed to identify specific allergens causing allergic reactions. These tests are particularly useful when skin tests can't be done due to skin conditions or when a patient is taking medication that could interfere with skin test results.

Types of Allergy Blood Tests

There are primarily two types of allergy blood tests: the enzyme-linked immunosorbent assay (ELISA, or EIA) and the radioallergosorbent test (RAST). Both tests measure the amount of immunoglobulin E (IgE) antibodies in your blood, which your body produces in response to allergens. The type of allergy blood test chosen often depends on several factors, including the patient's age, symptoms, and medical history. For a more detailed understanding of your allergies, your healthcare provider might recommend an at-home allergy test, which allows you to take the test at your convenience.

Pros and Cons of Allergy Blood Tests

Allergy blood tests offer several advantages. They are safe, can be performed irrespective of skin condition or medication use, and can test for multiple allergens at once. However, they have some drawbacks, including a longer wait time for results compared to skin tests and they may be less sensitive in detecting allergies. Understanding these pros and cons can help you make an informed decision about the best type of allergy test for you.

How to Prepare for an Allergy Test?

Preparing for an allergy test involves taking certain steps to ensure accurate results. This includes avoiding certain medications that could interfere with the test and providing a detailed medical history to the doctor.

Preparing for Your Appointment

Before your appointment, it's essential to understand how long the allergy test might take, so you can schedule your day accordingly. Also, refrain from taking antihistamines or other medications that might interfere with the test results for at least 5 to 7 days prior to testing. During the appointment, provide your healthcare provider with a detailed medical history, including any known allergies and their symptoms. Discuss any concerns you have about the procedure, and don't forget to ask about the next steps, like how to interpret your allergy test results.

What Can You Expect from an Allergy Test?

During an allergy test, you can expect a healthcare professional to expose your skin to small amounts of various allergens and observe the reactions. The test aims to identify specific substances causing allergic reactions.

Procedure Details

In a skin prick test, the most common type of allergy test, small drops of allergen extracts are applied on your skin using a tiny lancet. You'll wait for 15 to 20 minutes to see if any reactions, such as redness or swelling, occur. An allergy patch test, on the other hand, involves wearing patches with allergens on your skin for 48 hours. After the test, you'll receive an allergy test report, detailing the allergens causing your symptoms.


The main risk associated with allergy tests is an allergic reaction, which could range from mild irritation to a severe reaction. However, these tests are generally safe as they use tiny amounts of allergens. The testing is done under controlled conditions by trained professionals who are equipped to handle any severe reactions.

Side Effects of Allergy Blood Tests

Side effects of allergy blood tests are rare but may include light-headedness, fainting, or hematoma (a swelling of blood pooled under the skin). After the test, you might also experience slight discomfort or bruising at the site where the needle was inserted. However, these side effects usually resolve quickly.

How Are Allergy Blood Test Results Interpreted?

Interpreting allergy blood test results involves analyzing the level of specific IgE antibodies in your blood. These antibodies are produced by your immune system in response to allergens. Increased levels of specific IgE antibodies indicate that you may be allergic to the tested allergen.

In the test results, allergens are usually listed along with the corresponding IgE levels. High levels of IgE for a particular allergen suggest a possible allergy to that substance. However, the test results alone are not definitive. Your doctor will consider these results in combination with your symptoms and medical history to make an accurate diagnosis.

It's important to remember that allergy blood tests are sensitive to many allergens, including those specific to certain regions. For instance, if you've recently relocated, your allergy test results may reflect new sensitivities to allergens prevalent in your new location. You can refer to resources like Wyndly's Allergens by States & Location to gain insights about potential allergens in your area.

What Is the Diagnosis and Treatment of Allergies?

The diagnosis of allergies involves a combination of reviewing medical history, performing physical examinations, and conducting allergy tests. Once diagnosed, treatment options include avoidance, medications, and immunotherapy, with the objective to control symptoms and improve quality of life.

Sublingual Immunotherapy

Sublingual immunotherapy (SLIT) is a treatment option where small doses of an allergen are placed under your tongue to boost tolerance to the substance and reduce symptoms. The process begins with an escalation phase, where the allergen dose is gradually increased over time. This is followed by a maintenance phase, where a constant dose is administered. SLIT has been found to be effective in treating several types of allergies, including pollen, dust mites, and pet dander allergies. However, always remember to discuss with your healthcare provider before starting any new treatment regimen.

Live Allergy-Free with Wyndly

If you want long-term relief from your allergies, Wyndly can help. Our doctors will help you identify your allergy triggers and create a personalized treatment plan to get you the lifelong relief you deserve. Start by taking our quick online allergy assessment today!

Frequently Asked Questions

What indicates a positive result in an allergy test?

A positive result in an allergy test is typically indicated by a red, itchy bump, similar to a mosquito bite, which appears at the test site on the skin where the allergen was applied. For blood tests, a high level of specific IgE antibodies signifies a positive result.

What is the normal range for an allergy report?

Allergy reports, also known as allergen-specific IgE blood tests, typically use a scale of 0 to 6. A score of 0 indicates no allergy, while 1 to 2 is a low level, 3 to 4 is moderate, and 5 to 6 is a high level of allergen-specific antibodies.

What are the levels of allergy testing?

Allergy testing levels include skin prick tests, intradermal tests, and blood tests. Skin prick tests gauge immediate allergic reactions, while intradermal tests are used for detecting allergies to venom and antibiotics. Blood tests, on the other hand, measure the amount of specific allergen antibodies in the bloodstream.

How are allergy tests graded?

Allergy tests are graded based on the size of the skin's reaction to allergens. A "0" grade indicates no reaction, while a "4+" grade represents a large, raised wheal with surrounding redness. The size and severity of the reaction help determine the intensity of the allergy.

What does +2 mean on an allergy test?

In allergy testing, +2 indicates a moderate allergic reaction. It's typically characterized by a wheal (raised, red bump) of 5-10 mm in diameter, surrounded by redness (flare). This implies the presence of an allergy but it may not always mean symptoms will be experienced.

What are the symptoms after allergy testing?

After allergy testing, some people may experience redness and swelling at the test site, particularly if allergens were identified. These symptoms usually subside within a few hours. Less commonly, people may have a delayed reaction, including rashes and itching, which can last 24 to 48 hours.

What is the result of a drug allergy test?

A drug allergy test result can be either positive or negative. A positive result indicates that you have a drug allergy, while a negative result means you don't. The results will also specify the particular drug you're allergic to, helping guide your future medication choices.

Can you get an allergy test for medication?

Yes, you can get an allergy test for medication. These tests, often performed by allergists, can include skin tests or oral drug challenges under medical supervision. They help identify if a person is allergic to particular medications, aiding in safer prescription practices.

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