Interpreting Your Allergy Blood Test Results: A Detailed Guide

Wyndly Care Team
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What allergies can be detected from a blood test?

A blood test can detect allergies to pollen, mold, dust mites, animal dander, insect stings, foods such as peanuts, milk, eggs, wheat, soy, fish, shellfish, tree nuts, and fruits. It can also identify sensitivities to certain medications, latex, and substances like nickel.

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What Is a Blood Test for Allergies?

A blood test for allergies is a diagnostic procedure that measures the immune system's response to specific allergens in the bloodstream. Rather than inducing an allergic reaction, these tests measure the amount of antibodies produced when exposed to potential allergens.


Allergy blood tests are an excellent option for individuals who cannot undergo skin tests due to skin conditions or medication interference. They can detect a wide range of allergens, including foods, airborne substances, insect stings, and certain medicines. Blood tests for allergies are also suitable for patients with a high risk of severe allergic reactions.

Procedure Details

The procedure for an allergy blood test is straightforward and typically involves the following steps: A health care provider will clean a site on your arm and insert a needle into a vein to draw blood. The blood sample is then sent to a laboratory, where it's tested for the presence of antibodies. The amount of antibodies present in the blood indicates the severity of the allergy. These tests are quick, painless, and can be completed in one visit, typically taking less than an hour to complete. Allergy test completion times may vary.

Why Are Allergy Blood Tests Done?

Allergy blood tests are done to identify the specific allergens causing allergic reactions. These tests are a valuable tool in determining an effective treatment plan. They are particularly useful when skin tests are unsuitable or when a more comprehensive allergy profile is needed.

Allergy blood tests are often performed when individuals exhibit symptoms of allergic diseases but cannot undergo a skin allergy test due to certain medications, skin conditions, or a high risk of anaphylaxis. Blood tests can provide a detailed allergy profile, guiding clinicians and patients in managing and treating allergies effectively.

Furthermore, allergy blood tests are also performed to diagnose allergic asthma. They help identify the specific allergens that trigger asthma symptoms, enabling healthcare providers to develop a personalized treatment plan. Remember, understanding your allergic triggers is a crucial step in controlling your symptoms and improving your quality of life.

What Are the Types of Allergy Blood Tests?

There are primarily two types of allergy blood tests: the ImmunoCAP Specific IgE (sIgE) blood test and the Radioallergosorbent (RAST) test. Both tests aim to detect specific antibodies in the blood that respond to allergens.

The ImmunoCAP Specific IgE blood test is often used due to its high accuracy and extensive allergen database. It measures the amount of allergen-specific IgE antibodies in the blood, which helps determine if a person has a specific allergy. As a result, this test can provide a comprehensive allergy profile.

On the other hand, the RAST test, an older version of allergy blood testing, is less commonly used today. It measures the total amount of IgE antibodies in the blood in response to an allergen. The RAST test can still be useful, especially if the ImmunoCAP sIgE test is unavailable.

Remember, the choice of test depends on several factors, including the patient's age, symptoms, medical history, and specific needs. Your healthcare provider will guide you in choosing the best type of allergy test for your situation.

How to Interpret Allergy Blood Test Results?

Interpreting allergy blood test results involves understanding the specific levels of allergen-specific IgE antibodies present in your blood. The results are usually reported as a numerical value, with higher numbers indicating a stronger allergic response.

The numerical value range differs based on the specific allergen tested. A result of zero usually means that you are not allergic to the tested allergen. On the other hand, a high value may suggest a possible allergy. However, it's important to note that a higher numerical value doesn't necessarily correlate with the severity of symptoms.

There's more to interpreting your allergy blood test results than just reading numbers. The results should be evaluated in conjunction with your symptoms, medical history, and physical examination. Therefore, it's essential to discuss the results with a healthcare professional who can provide a comprehensive understanding of your potential allergies.

Knowing how to interpret your allergy blood test results can give you a clear understanding of your allergies, helping you make informed decisions about your health. Apart from blood tests, you can also consider other types of allergy tests like skin tests, which can be interpreted using allergy skin test results. Always remember, the cost of an allergy test varies depending on the type of test, your location, and health insurance coverage.

What Are the Pros and Cons of Allergy Blood Tests?

Allergy blood tests, like any diagnostic tests, come with their own set of advantages and disadvantages. Understanding these can help make an informed decision about whether to opt for this type of testing.


One of the key advantages of allergy blood tests is that they are safe for almost everyone, including infants, pregnant women, and people with severe skin conditions. These tests are not affected by medications like antihistamines or steroids, allowing for more flexibility in testing. Furthermore, with a single blood draw, multiple allergens can be tested simultaneously, making it a comprehensive assessment tool.


On the downside, allergy blood tests can be more expensive than other types of allergy tests, such as skin tests. They also may not be as sensitive in detecting certain allergies compared to skin tests. The results from blood tests take longer to obtain, typically several days, whereas skin test results are available within 20 minutes. Finally, the results can sometimes be harder to interpret, requiring medical expertise for an accurate understanding.

What Are the Side Effects of Allergy Blood Tests?

Side effects from allergy blood tests are extremely rare and typically mild when they do occur. Unlike other allergy tests, such as allergy patch tests, blood tests pose no risk of triggering a full-blown allergic reaction.

Potential side effects are generally associated with the blood draw procedure itself rather than the allergy testing. These may include slight pain or bruising at the injection site, lightheadedness, or, in rare cases, fainting.

Infection or excessive bleeding at the puncture site is extremely rare, particularly when the blood draw is conducted by a trained healthcare professional. It's important to inform the healthcare provider of any blood-clotting disorders or if you're taking blood-thinning medication.

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Frequently Asked Questions

What is the normal range for an allergy blood test?

The normal range for an allergy blood test, specifically an Immunoglobulin E (IgE) test, is typically below 100 KU/L (Kilo Units per Liter). However, this can vary slightly depending on the lab. Higher levels may indicate an allergic reaction, but they should be interpreted alongside symptoms and medical history.

How do I read my allergy blood test results?

Interpreting allergy blood test results involves understanding immunoglobulin E (IgE) levels. Higher IgE levels generally indicate allergies. Specific IgE levels match specific allergens, like dust mites or pollen. However, it's essential to discuss these results with a healthcare provider for a precise interpretation.

How accurate is the blood test for allergies?

Blood tests for allergies, like the ImmunoCAP Specific IgE blood test, are quite accurate, with a sensitivity of about 90%. However, they may occasionally yield false positives. For optimal accuracy, they should be combined with a detailed medical history and possibly skin tests.

What does a blood test for allergies show?

A blood test for allergies measures the amount of specific antibodies, known as Immunoglobulin E (IgE), in your bloodstream. These antibodies are produced by your immune system in response to allergens. High levels of IgE may indicate an allergic reaction to a particular substance.

What do the results of an allergy test mean?

Allergy test results indicate whether you have a specific allergy. A positive result means you're allergic to a particular substance, while a negative result means you're not. However, false positives and negatives can occur, so it's crucial to discuss your results with a healthcare provider.

Is there a blood test for medication allergies?

Yes, there is a blood test for medication allergies known as an immunoassay. This test measures the concentration of specific antibodies to a drug in the bloodstream. However, it's not always definitive, as negative results don't completely rule out an allergy. Always consult a healthcare provider.

Does allergy medicine affect blood test results?

Certain allergy medications, particularly antihistamines, can interfere with allergy blood tests, potentially leading to inaccurate results. It's advised to stop taking these medications at least a week before the test, but always consult with your healthcare provider for personalized advice.

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