What is an allergy blood test?
An allergy blood test measures specific IgE, the antibody behind hay fever, allergic hives and food allergy. Each allergen on the panel gets its own result.
A positive result means your immune system has made IgE to that allergen. Doctors call this sensitization. Sensitization is not the same as an allergy. Many people are sensitized to a food or pollen and never react to it.
Some panels also measure food-specific IgG and sell it as a "food sensitivity" or "chronic allergen" test. That is a different antibody with a different meaning, covered below. The hormone and allergy tests page shows where allergy panels sit among other specialized blood tests.
What do the three iHope Clinic panels measure?
New Dawn Health books three allergy panels at iHope Clinic in Taipei. The clinic's listing says each runs on a microarray chip from one blood sample. The panels are offered through the clinic by Excelsior Bio-System (EBS). In the package names, "acute" means IgE and "chronic" means IgG.
| Package | Lab code | IgE: environmental allergens | IgE: foods | IgG: foods |
|---|---|---|---|---|
| 110-item Acute Allergen Test | GE110 | 22 | 44 | 44 |
| 101-item Chronic Allergen Panel | G101 | None | None | 101 |
| 224-item Acute and Chronic Allergen Test | GE224 | 22 | 101 | 101 |
The environmental allergens are dust mites, cockroach, animal dander, molds and pollens. Two points follow from the table:
- The 110-item test is not IgE only. Its name says "acute", but 44 of its 110 items are IgG.
- The 101-item panel contains no allergy test. It measures IgG only.
"Acute" and "chronic" are not medical categories. The laboratory medicine department at National Taiwan University Hospital states that they are not a scientific classification.
How does a blood IgE test compare with a skin-prick test?
Both tests look for the same antibody. A skin-prick test finds IgE on cells in the skin. A blood test finds IgE in the blood. Their results do not always agree.
| Blood specific IgE | Skin-prick test | |
|---|---|---|
| How it is done | One blood draw | A tiny prick through a drop of each allergen on the skin |
| When you see a result | Later, once the lab has processed the sample | Within about 20 minutes, in the allergist's office |
| Antihistamines | Do not interfere | Must be stopped 3 to 7 days before |
| Widespread eczema or dermatographism | Can still be done | Can rule the test out |
| Strength | Gives a measured level for each allergen | Generally more sensitive |
| Risk | Slight pain or a bruise at the needle site | Small itchy bumps that usually fade within 30 minutes; done where anaphylaxis can be treated |
| In Taiwan | The most widely used allergy test | Standardized skin-test extracts are not licensed; some doctors prick the skin with fresh food instead |
Neither test diagnoses an allergy alone. The US expert panel convened by the National Institute of Allergy and Infectious Diseases (NIAID) recommends both for finding foods that may cause reactions. It states that, alone, neither is diagnostic.
Why can a positive result be wrong?
A positive IgE test shows sensitization, and many sensitized people are not allergic. The NIAID guidelines say both IgE tests have poor specificity. Used alone, they lead to gross over-diagnosis of food allergy.
The World Allergy Organization (WAO) reports that food allergy affects 2–3% of adults. It also reports that one in three people believe they are allergic or intolerant to at least one food. The NIAID guidelines cite studies showing that 50% to 90% of presumed food allergies are not allergies.
Each extra allergen on a panel is another chance of a positive that means nothing. That is why guideline bodies want the test chosen from your history:
| Body | Position |
|---|---|
| AAAAI, Choosing Wisely (US, 2012) | Don't perform IgG testing or an indiscriminate battery of IgE tests in the evaluation of allergy. Specific IgE testing should be guided by history and examination. |
| NIAID expert panel (US, 2010) | Tests should follow the medical history and should not be large general panels of food allergens |
| NICE (UK, 2011; children and young people) | Do not carry out allergy testing without first taking an allergy-focused clinical history |
| World Allergy Organization (2020) | A positive IgE result without a history of allergic symptoms should be called clinically irrelevant |
A negative result has a limit too. The AAAAI warns that an undetectable level is not necessarily a negative result. If you have reacted to a food before, a blood test alone is not a reason to eat it again.
Do IgG "food sensitivity" tests diagnose intolerance?
No. Allergy societies and guideline bodies in the US, Canada, Europe, the UK and Australia have reviewed food IgG testing, and so has National Taiwan University Hospital. None supports it for diagnosing food allergy. The AAAAI, EAACI and CSACI also reject it for intolerance.
The AAAAI calls food IgG likely a normal immune response to eating the food. The European Academy of Allergy and Clinical Immunology (EAACI) describes food IgG4 as a sign of repeated exposure and of tolerance. It is not a sign of allergy or intolerance.
| Body | Position |
|---|---|
| EAACI (Europe, 2008) | Food-specific IgG4 does not indicate food allergy or intolerance; the test should not be performed for food-related complaints |
| AAAAI (US) | IgG food testing has never been scientifically proven to do what it reports; recommends against it for diagnosing food allergy or intolerance |
| CSACI (Canada, 2012) | Strongly discourages food-specific IgG testing; positive results are expected in healthy adults and children |
| NIAID expert panel (US, 2010) | Lists allergen-specific IgG4 among nonstandardized tests not to use in the routine evaluation of food allergy |
| NICE (UK, 2011; children and young people) | Do not use serum-specific IgG testing to diagnose food allergy |
| ASCIA (Australia and New Zealand, 2024) | IgG to foods is an unproven test it does not recommend |
| National Taiwan University Hospital (2026) | A high IgG level only reflects frequent exposure; avoiding foods because of it has no evidence behind it; not recommended for the general public |
The harm lies in the diet that follows. CSACI warns of unnecessary food restrictions and a lower quality of life. The AAAAI warns that IgG-based diets can be nutritionally inadequate.
Who should get tested, and who should skip it?
| Your situation | Is an allergy blood test useful? |
|---|---|
| Sneezing, runny nose, itchy eyes or wheezing, especially around pollen, dust or pets | Yes. IgE to environmental allergens can show what to avoid. The AAAAI's example: testing shows a dust mite allergy but no pet allergy, so the pet can stay. |
| Hives, swelling, vomiting or breathing trouble soon after a particular food | Yes, for that food and related foods. Take the result to an allergist. |
| You cannot stop antihistamines, or you have widespread eczema | A blood test is the usual choice over a skin test |
| Hives that keep coming back with no clear trigger | Usually not. The AAAAI says IgE testing for foods or inhalants is not indicated in chronic hives without a clear history. |
| Bloating, cramping, diarrhea, fatigue or brain fog | Usually not. The AAAAI says chronic diarrhea and cramping alone are not usually a reason for allergy skin testing, and that IgG panels are unproven. |
| No symptoms; you want a baseline | No. Testing without a matching history is what the AAAAI and NICE advise against. |
| A past severe reaction to a food | Test only with an allergist. Never reintroduce a food because a panel came back negative. |
Do I need to stop antihistamines or other medicines?
Not for the blood test. Antihistamines block the skin's reaction, so they are stopped before a skin-prick test. ACAAI says medicine does not interfere with allergy blood test results. The WAO review also lists freedom from antihistamine effects among the advantages of blood IgE assays.
| Medicine | Before a skin-prick test | Before a blood IgE test |
|---|---|---|
| Antihistamine tablets, such as cetirizine, loratadine or fexofenadine | Stop 3 to 7 days before (ACAAI); WAO advises most for 4–5 days, ideally 7 | No need to stop |
| H2 blockers for acid, such as famotidine | Stop 24 hours before (WAO) | No need to stop |
| Antidepressants with antihistamine activity | Stop 1 week before, only if the prescriber agrees (WAO) | No need to stop |
| Leukotriene blockers, such as montelukast | No need to stop (WAO) | No need to stop |
MedlinePlus says a provider may still ask you to pause antihistamines before an allergy blood test. If the clinic's instructions differ from this table, follow the clinic. Never stop a prescribed medicine without asking the doctor who prescribed it.
What happens on the day?
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1Before you goAn allergy blood test needs no special preparation. Your coordinator confirms the instructions for your panel when you book.
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2Write down your historyList what you react to, how soon after contact, and what happened. That list is what makes the result readable later.
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3The blood drawA health professional takes one blood sample from a vein in your arm. iHope Clinic lists the visit as 30 minutes.
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4AfterwardsSlight soreness or a small bruise where the needle went in is the usual side effect.
What are the risks?
The blood draw carries very little risk. MedlinePlus lists slight pain or bruising at the needle site. The larger risks come from reading the result wrongly:
- Cutting foods you tolerate. The AAAAI says well-tolerated foods should not be removed from the diet, even with a positive test.
- A diet too narrow to be healthy. ASCIA warns that unproven tests can lead to costly and often dangerous dietary restrictions.
- False reassurance. A negative blood result does not clear a food you have reacted to before.
- A delayed diagnosis. The WAO warns that unproven tests can delay the right diagnosis and treatment.
How is a result used, and what happens after I fly home?
Blood results take longer than a skin test, because a lab processes the sample. When the report arrives, and in which language, is confirmed when you book.
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1Match each positive to your historyA positive IgE result for a food you eat without trouble is usually sensitization only. Keep eating it unless a doctor tells you otherwise.
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2Set the IgG results asideDo not cut a food because its IgG level is high. Allergy societies read a high IgG as a sign that you eat that food.
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3Take the full report to an allergistBring the lab name, the method and the units. Results from different labs and assay systems may not be comparable, and the allergist may want to repeat selected tests.
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4Confirm with a food challenge if neededWhen history and tests leave doubt, an allergist gives you the food in slowly increasing amounts under supervision. This oral food challenge is the reference standard for diagnosing food allergy.
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5Plan treatment for confirmed triggersOnce the allergist confirms what you react to, you and the doctor build a treatment plan together.
An oral food challenge is not something to fit into a short trip. National Taiwan University Hospital notes that it can trigger a severe reaction. It should follow an allergist's assessment, in a setting equipped for emergencies.
How much does it cost?
The live prices further down this page are New Dawn Health's booking prices for the three iHope Clinic panels. Some check-up packages also include an allergen panel, and each package card lists what it covers.
- The panels differ in content. The 224-item and 110-item tests each list 22 environmental allergens; the 224-item test adds more foods on both the IgE and the IgG side.
- Only the IgE items address allergy. They are most useful for the allergens your history points to.
- Insurance at home is a question for your insurer. Ask before you book whether it reimburses allergy testing done abroad.
