Blood Test for Allergy

Overview

What is an allergy blood test?

An allergy blood test is a diagnostic tool that is used to check specific antibody levels known as immunoglobulin E (IgE) in your blood. This helps identify substances that might cause allergic reactions. 

This blood test for skin allergy is helpful if you have skin conditions, taking medications that could interfere with skin testing, or at risk of severe allergic reactions from traditional skin tests.

Common allergens include:

1. Foods
2. House dust
3. Latex
4. Insect bites and stings
5. Molds
6. Pet dander
7. Pet urine
8. Pet saliva
9. Pollens
10. Medications like penicillin 

If suggested, doctors examine your blood sample to identify allergies to common triggers like pollen, dust, certain foods, or pet dander, which can help in recommending personalized treatment plans and managing your allergies.

What are the different types of allergy blood tests?

Two different types of allergy blood tests are:

• Total IgE Test: It measures the overall level of IgE antibodies in your blood, which can indicate if you have an allergy but doesn’t specify the allergen. 
• Specific IgE Test: The test helps the amount of IgE your body makes in response to particular allergens like pollen, dust, foods, or animal dander. Each allergen is tested separately to pinpoint your triggers. 
• Enzyme-linked Immunosorbent Assay (ELISA or EIA): It is a laboratory method to detect and measure specific IgE antibodies against allergens in the blood. 
• Radioallergosorbent Test (RAST): It is a traditional method for measuring specific IgE antibodies. This method is less common due to advancements in ELISA technology. 

In some cases, a blood test for skin allergy may also check for increased levels of certain white blood cells, such as eosinophils. These levels are usually elevated in allergic conditions, though this is not specific to allergies alone. 

This blood test measures IgE antibodies in your blood to help diagnose skin allergies and can be especially useful if you have skin conditions or are unable to undergo traditional skin prick testing. 

When do providers suggest an allergy blood test?

Healthcare providers suggest a blood test for allergy detection when:

• Skin tests are not safe or suitable: If you suffer from severe eczema, psoriasis, or other skin conditions, the skin prick testing fails to deliver accurate results.
• If you are on medications such as antihistamines, antidepressants, or steroids, these medicines can interfere with skin test results, making an allergy blood test a better option.
• For young children or infants: Blood tests are considered a safer and easier option to determine the cause. Some children may not tolerate skin pricks well.  
• To investigate unexplained allergic symptoms: A blood test for allergy detection is also prescribed to investigate unexplained allergic symptoms such as persistent sneezing, hives, runny nose, watery eyes, rashes, swelling, or breathing issues (dyspnea) with no clear cause. 
• To check for food, environmental, or insect allergies: The need for blood tests is also created to check for food, environmental, or insect allergies. Especially, when symptoms may be delayed or not clearly linked to a specific exposure. 
• When a detailed, specific allergen profile is needed: Apart from all these reasons above, blood tests can measure the level of IgE antibodies against individual allergens, suggesting a precise treatment. 

Test Details

What is the procedure of the allergy blood test?

An allergy blood test works by measuring the immunoglobulin (IgE) antibodies levels in your blood. These antibodies are produced in response to specific allergens. 

A step-by-step guide information how it works:

• A phlebotomist will insert a needle in a vein of your arm to draw a small sample of blood. 
• The blood sample is sent to a lab for testing against a panel of common allergens like pollen, dust, molds, foods, or pet dander. 
• The test checks for specific IgE antibodies associated with particular allergens. If your allergy blood test shows higher-than-normal levels, it may indicate allergy. 
• Sometimes increased eosinophil count may also be checked, a type of white blood cell often elevated during allergic reactions. 

Note: A blood draw for an allergy blood test might cause a mild pinch and some discomfort due to needle insertion. However, symptoms will disappear in 2-3 days. In case of infection or excessive bleeding, seek medical assistance immediately. 

Discuss your reports with your doctor to know which allergens are responsible for causing symptoms and how powerful is your immune system. 

How can you prepare for an allergy blood test?

Consult your doctor if you need to do anything special for a blood test for allergy detection. Usually, it requires no preparation, allowing you to eat your regular meals and stay hydrated before the test. 

Results and Follow-Up

What does an allergy blood test result indicate?

A blood test for skin allergy and other allergy blood tests can indicate positive, negative, or mild elevation.

Positive Results 

• A positive allergy blood test indicates elevated IgE levels , suggesting your body is sensitive or allergic to specific substances such as pollen, dander, dust, or certain foods. 

Negative Results

• A negative allergy blood test pinpoints towards normal IgE levels. You are unlikely to have an allergy. However, the test does not rule out non-IgE-mediated reactions like food intolerances or delayed reactions. 

Mild Elevations

The test may also suggest mild sensitivity that may need a further investigation. Hence, additional testing may also be needed. 

Note: Do not make any assumptions. Discuss your blood test for allergy detection report with your doctor to understand what your specific results mean. 

When are the allergy blood test results available?

Allergy blood test results are typically available in a day, but they could take more or less time. 

Can a blood test for allergy detection deliver false-positive results?

Yes. Blood tests for allergy detection can deliver false-positive results. This indicates the test may show you are allergic to something that does not even exist. False positives can occur due to high total IgE levels, recent food intake, or other conditions. 

About 50–60% of positive blood allergy tests may not show a true clinical allergy. Therefore, test results are always interpreted along with your medical history and symptoms. 

When should you call a doctor?

You should call a doctor if you have:

• Persistent symptoms that don’t improve
• Unexplained skin reactions
• Breathing difficulties
• Symptoms after eating specific foods or medications
• History of allergic reactions
• Signs of a severe allergic reaction (anaphylaxis) 

Additional Common Questions

What is the difference between an allergy blood test and allergy skin test?

Below is a table showing an allergy blood test vs. a blood test for skin allergy. A general overview. 

Feature	Allergy blood test	Allergy skin test
Invasiveness	Less invasive	Involves pricking or scratching the skin
Medication impact	Not affected by most medications	Certain medications like antihistamines must be stopped before the test.
Speed of results	Results are available in a day or days (may vary depending on the procedure and other conditions.)	Results are available within 15-20 minutes (may vary depending on the procedure and other conditions. )
Sensitivity	Less sensitive for more allergens	More sensitive, mainly in airborne and some food allergens.
Risk of reaction	No risks	Small risk of allergic reaction.
Best for	People with skin conditions, those on medications, or needing many allergens tested.	Quick diagnosis, high sensitivity, and when drug allergies are suspected

A Note from Redcliffe Labs

At Redcliffe Labs, we understand how certain allergies can impact your daily life. Common symptoms include persistent sneezing, skin rashes, unexplained fatigue, and food sensitivities. That’s why we have a series of allergy blood tests designed to help you identify the exact allergens triggering your symptoms.

Our allergy blood test measures IgE antibody levels in your blood, helping indicate specific allergens such as dust mites, pollen, pet dander, foods, and more. 

The test is quick, safe, and ideal for individuals of all ages. With accurate results and expert guidance, our goal is to support your journey toward better health and symptom-free living.