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IgE (Total & Specific Allergy) Blood Test

IgE is an antibody produced by the immune system in response to allergens and parasites. A high total IgE suggests an allergic condition. Specific IgE tests can pinpoint exactly which allergen is triggering your symptoms.1

Written by Suman Konda, Clinical Pharmacist · Based on peer-reviewed sources · Editorial policy · Not medical advice

Last reviewed and updated: · How we check our content

Quick answer

Total IgE reflects overall allergic tendency; normal in adults is below 100 IU/mL. Specific IgE tests identify the exact trigger (pollen, foods, insect stings) and are reported in classes 0-6, with class 2 and above usually relevant. Levels above 500 raise the question of parasites or significant atopic disease. A positive result means sensitisation, which must match symptoms to matter.

What is IgE?

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Immunoglobulin E (IgE) is an antibody class produced by plasma cells (immune cells) in response to allergens: substances the immune system mistakenly identifies as threats, such as pollen, pet dander, dust mites, foods and insect stings. IgE binds to mast cells in tissues. When the allergen is encountered again, IgE triggers mast cell degranulation, the release of histamine and other chemicals that cause allergy symptoms. Total serum IgE gives a general picture; specific IgE tests (also called RAST or ImmunoCAP) identify which specific allergens you are sensitised to.

Total IgE normal range

AgeNormal Total IgE (IU/mL or kU/L)
Adults< 100 IU/mL (some labs up to 150)
Children (2-10 yrs)< 100 IU/mL
High allergy load100 – 500 IU/mL
Very high> 500 IU/mL (consider parasites, atopic disease)
Hyper-IgE syndrome> 2,000 IU/mL
Key points
  • IgE is the antibody behind allergic reactions; total IgE gives a general picture, while specific IgE (RAST/ImmunoCAP) identifies the exact trigger.
  • Normal total IgE is generally below 100 IU/mL (some labs up to 150); levels above 500 raise the question of parasites or significant atopic disease.
  • Specific IgE results are reported in classes 0 to 6; class 2 and above is typically considered clinically relevant.
  • Raised IgE is seen in hay fever, asthma, eczema, food allergy, ABPA, some drug reactions, and parasitic infections, a key cause in tropical regions.
  • IgE testing does not help in all conditions; a positive specific IgE means sensitisation, which must match the clinical history to matter.
  • Skin prick testing and blood specific IgE complement each other; neither replaces the history.

Causes of high total IgE

ConditionIgE LevelNotes
Allergic rhinitis (hay fever)Mildly elevatedSpecific IgE to pollen positive3
Asthma (allergic)Mildly-moderately elevatedInhaled allergens trigger attacks
Atopic dermatitis (eczema)Often very highSkin barrier dysfunction and allergy
Food allergyMildly-moderately elevatedSpecific IgE to foods (peanut, milk, egg etc.)2
Parasitic infections (worms)Very highKey cause in tropical regions
Allergic bronchopulmonary aspergillosis (ABPA)Very highFungal allergy in lungs
Drug allergyVariableSome drug reactions are IgE-mediated

Specific IgE testing (RAST / ImmunoCAP)

Specific IgE tests measure IgE antibodies against individual allergens in a blood sample. Common panels include: respiratory (dust mite, grass pollen, cat/dog dander, mould), food (peanut, tree nuts, milk, egg, wheat, shellfish), insect sting (bee, wasp) and latex. Results are reported in classes from 0 (not detected) to 6 (very high). Class ≥2 is typically considered clinically relevant.

Questions to ask your doctor

  • Should I have a specific IgE panel to identify my trigger allergens?
  • Do I need a skin prick test as well?
  • Could a parasitic infection be causing my high IgE?
  • Am I a candidate for immunotherapy (allergy shots or sublingual drops)?
  • Should I carry an adrenaline (epinephrine) auto-injector?

IgE myths vs facts

Allergy blood testing is widely ordered and widely misread. Here is what the evidence actually says:

MYTH A total IgE of 800 means severe allergy.

Fact: Total IgE is a blunt instrument — it rises in allergy, but also in eczema, parasites, some infections and smokers. Severity is judged by symptoms and specific IgE to actual triggers, not by the total number.

MYTH Antihistamines ruin the IgE blood test.

Fact: Unlike skin prick testing, which antihistamines suppress, the blood test measures antibodies directly — antihistamines don't change it. Don't suffer through stopping them for a blood draw; confirm with your doctor which test you're having.

MYTH Normal IgE rules out allergy.

Fact: It doesn't — some people with genuine allergies (a child with eczema, for instance) have normal total IgE. Specific IgE to the suspected trigger, and the clinical history, carry more weight than the total.

MYTH The bigger the allergen panel, the better.

Fact: Large panels generate positive results to things you tolerate perfectly well — sensitisation without symptoms is common and not an allergy. Testing should follow the history: suspected triggers first, not a 50-allergen trawl.

MYTH A positive specific IgE means you must avoid that food forever.

Fact: Specific IgE shows sensitisation, not always clinical allergy — many positives never cause symptoms. Elimination decisions need the history (and sometimes supervised food challenges), not the number alone.

Your IgE result: what to do next

Got your report and wondering what it means for you? Find the branch that matches your situation — every path ends with your doctor, because allergy is diagnosed from history plus tests, never tests alone:

If your result is…Sensible next stepTalk to your doctor when…
High total IgE, no clear triggerNon-specific — eczema, parasites and infections raise it too; specific IgE follows the history.symptoms point at a trigger; don't chase the total number itself.
Positive specific IgE matching symptomsSupports the allergy diagnosis; avoidance and management plans follow.promptly if reactions are severe — an action plan and emergency medicines matter.
Positive specific IgE, no symptomsSensitisation without allergy is common — no elimination without clinical reason.before cutting foods; unnecessary avoidance harms nutrition.
Normal IgE with convincing symptomsDoesn't rule allergy out — history-led specific testing or referral still applies.symptoms persist; some allergies hide from blood tests.

IgE test price in India

In India, the IgE test typically costs &rupee;700–&rupee;1,400, though prices vary by city and lab — total IgE at the lower end, specific-allergen panels higher. Testing should follow the clinical history rather than defaulting to the largest panel, which also keeps costs sensible. Where possible, choose a NABL-accredited lab, and remember the range printed on your own report is the one that counts.

Frequently Asked Questions

My total IgE is 800. Does that mean severe allergy?
Not on its own. Total IgE is a general gauge — infections such as intestinal worms can raise it into the hundreds without any allergy. What matters is which specific IgE tests are positive and how that matches your symptoms.
Can I do the IgE test while taking antihistamines?
Yes. Unlike skin prick tests, blood IgE levels are not suppressed by antihistamines, so you don’t need to stop them — that is one practical advantage of the blood test. Still, tell the lab everything you are taking.
My child has eczema but normal IgE. Is allergy ruled out?
No. Many children with eczema or food allergy have a normal total IgE; the diagnosis rests on symptoms and specific testing, not the total. Discuss next steps with your paediatrician rather than relying on this one number.
Should I get the full 50-allergen panel?
Usually not as a first step. Broad panels often return weak positives of unclear meaning and cost a lot. Testing the few allergens that match your symptoms — guided by your doctor — gives more useful answers for less money.
How much does the IgE test cost in India?
The IgE test typically costs ₹700–₹1,400 in India, though prices vary by city and lab. Choose a NABL-accredited lab where possible — and remember the reference range printed on your own report is the one that counts. Discuss the result with your doctor.
What is IgE?
Immunoglobulin E (IgE) is an antibody class produced by plasma cells (immune cells) in response to allergens: substances the immune system mistakenly identifies as threats, such as pollen, pet dander, dust mites, foods and insect stings. IgE binds to mast cells in tissues. When the allergen is encountered again, IgE triggers mast cell degranulation, the release of histamine and other chemicals that cause allergy symptoms. Total serum IgE gives a general picture; specific IgE tests (also called RAST or ImmunoCAP) identify which specific allergens you are sensitised to.
What is specific IgE testing (RAST / ImmunoCAP)?
Specific IgE tests measure IgE antibodies against individual allergens in a blood sample. Common panels include: respiratory (dust mite, grass pollen, cat/dog dander, mould), food (peanut, tree nuts, milk, egg, wheat, shellfish), insect sting (bee, wasp) and latex. Results are reported in classes from 0 (not detected) to 6 (very high). Class &ge;2 is typically considered clinically relevant.
What is total IgE versus specific IgE, what each test tells you?
There are two distinct IgE measurements, and they answer different clinical questions:
What is skin prick testing versus blood sIgE, when to use which?
Both skin prick testing (SPT) and specific IgE blood tests detect IgE-mediated sensitisation, but they differ in practical terms:
What is conditions where IgE testing does NOT help?
Not all adverse reactions to foods or substances are IgE-mediated. IgE testing is unhelpful and should not be ordered for:

Pharmacist's practical notes

The panel-size trap is the expensive one: a 50-allergen panel in someone with a clear dust-mite history mostly buys confusing positives to foods they eat daily without trouble. History-led testing — suspected triggers first — is both better medicine and cheaper.

Antihistamines don't affect the blood test (unlike skin prick testing), so there's no need to suffer withdrawal before a blood draw — but do tell the lab which test you're having, since the preparation differs. And a positive specific IgE without symptoms is sensitisation, not allergy: don't start elimination diets off a number alone.

In India

The IgE test typically costs &rupee;700–&rupee;1,400 in India, though prices vary by city and lab.

Where possible, choose a NABL-accredited lab. Dust-mite and pollen triggers dominate in most Indian cities — testing usually starts there, guided by symptoms.

References

Sources cited on this page. PubMed links open the original abstract.

  1. Johansson SGO, Bieber T, Dahl R, et al. Revised nomenclature for allergy for global use. J Allergy Clin Immunol. 2004;113(5):832–836. PMID 15131563 · doi:10.1016/j.jaci.2003.12.591
  2. Anvari S, Miller J, Yeh CY, Davis CM. IgE-Mediated Food Allergy. Clin Rev Allergy Immunol. 2019;57(2):244–260. PMID 30370459 · doi:10.1007/s12016-018-8710-3
  3. Wise SK, Damask C, Roland LT, et al. International consensus statement on allergy and rhinology: Allergic rhinitis – 2023. Int Forum Allergy Rhinol. 2023;13(4):293–859. PMID 36878860 · doi:10.1002/alr.23090

Total IgE versus specific IgE, what each test tells you

There are two distinct IgE measurements, and they answer different clinical questions:

  • Total IgE: Measures all IgE antibodies in the blood regardless of what they target. A raised total IgE (above 100–120 kU/L in adults) suggests an atopic constitution (tendency to allergic conditions) or parasitic infection, but does not identify which allergen is responsible. Extremely high total IgE (above 2000 kU/L) can indicate allergic bronchopulmonary aspergillosis, hyper-IgE syndrome, or tropical parasitic infection.
  • Specific IgE (sIgE, formerly RAST): Measures IgE antibodies directed against a particular allergen, grass pollen, cat dander, peanut protein, house dust mite, cow's milk protein, etc. A raised sIgE to a specific allergen means the immune system has been sensitised to it, but sensitisation does not always equate to clinical allergy. Positive results must be interpreted alongside the patient's history.

Modern specific IgE panels (component-resolved diagnostics) go further, testing against individual protein components within an allergen. For peanut allergy, for example, Ara h 2-specific IgE is a far stronger predictor of severe systemic reactions than a positive result to whole peanut extract.

Skin prick testing versus blood sIgE, when to use which

Both skin prick testing (SPT) and specific IgE blood tests detect IgE-mediated sensitisation, but they differ in practical terms:

  • Sensitivity: SPT is generally slightly more sensitive for inhalant allergens (pollens, animal dander). Blood sIgE is equally or more sensitive for food allergens.
  • Antihistamine interference: SPT cannot be performed while the patient is taking antihistamines (they suppress the skin reaction). Blood sIgE can be measured at any time regardless of antihistamine use.
  • Safety: SPT carries a very small risk of systemic reaction in highly sensitised patients. Blood tests carry no such risk.
  • Immediate results: SPT results are available in 15–20 minutes. Blood sIgE results take 24–48 hours.

NICE guidelines (CG116) recommend that allergy testing should always be interpreted by a clinician with allergy training alongside a detailed history, neither test alone is sufficient to diagnose clinical allergy.

Conditions where IgE testing does NOT help

Not all adverse reactions to foods or substances are IgE-mediated. IgE testing is unhelpful and should not be ordered for:

  • Food intolerances (e.g., lactose intolerance, FODMAP sensitivity), these are enzyme deficiencies or gut fermentation issues, not immune reactions.
  • Non-IgE-mediated food allergies (e.g., food protein-induced enterocolitis syndrome, FPIES), mediated by T cells, not IgE.
  • Contact dermatitis (e.g., nickel allergy), mediated by T cells; diagnosed by patch testing.
  • Drug intolerances that are pharmacological rather than immunological.

The widespread ordering of IgE panels for unexplained fatigue, joint pains, or non-specific symptoms is not supported by evidence and leads to unnecessary dietary restriction.

Medical Disclaimer: This page is for general educational purposes only and does not constitute medical advice. Always consult a qualified doctor for diagnosis and treatment decisions.
Written and medically reviewed by Suman Konda, Clinical Pharmacist · Sources linked to PubMed · Not medical advice: see our disclaimer