Allergy Blood Test
Feb 2, 2026
Allergy Blood Test
An allergy blood test measures specific IgE (immunoglobulin E) antibodies in your blood to identify exactly what triggers your allergic reactions—whether that's foods, pollen, dust mites, pet dander, mould, or other allergens. Unlike skin prick tests, blood tests can be done regardless of skin conditions or antihistamine use, making them the gold standard for comprehensive allergy investigation.
At Blood Test London, allergy testing costs from £245 with results in 2-3 days.
Find Out What You're Allergic To
How Allergy Blood Tests Work
When you're allergic to something, your immune system produces specific IgE antibodies against that allergen. These antibodies remain in your blood even when you're not having a reaction.
What We Measure
Test Type | What It Shows |
|---|---|
Total IgE | Overall allergic tendency |
Specific IgE | Antibodies to individual allergens |
Component testing | Specific proteins within allergens (advanced) |
Results Interpretation
IgE Level (kU/L) | Interpretation |
|---|---|
<0.35 | Negative (no sensitisation) |
0.35-0.70 | Low positive |
0.71-3.50 | Moderate positive |
3.51-17.50 | High positive |
>17.50 | Very high positive |
Note: Positive IgE indicates sensitisation, not necessarily clinical allergy. Correlation with symptoms is essential.
Common Allergen Panels
Respiratory Panel - £345
Tests for airborne allergens:
Tree pollen: Birch, oak, plane
Grass pollen: Timothy, rye grass
Weed pollen: Nettle, mugwort
House dust mites: D. pteronyssinus, D. farinae
Pet dander: Cat, dog
Moulds: Aspergillus, Alternaria, Cladosporium
Food Panel - £395
Common food allergens:
Nuts: Peanut, tree nuts (almond, hazelnut, walnut, cashew, Brazil)
Seafood: Fish mix, shellfish mix
Dairy: Cow's milk proteins
Eggs: Egg white, egg yolk
Wheat/Gluten: Wheat, gluten
Others: Soya, sesame
Comprehensive Panel - £545
Both respiratory and food panels combined (40+ allergens)
Allergy vs Intolerance: Key Differences
Feature | Allergy (IgE) | Intolerance |
|---|---|---|
Immune system | IgE-mediated | Non-IgE or non-immune |
Timing | Minutes to 2 hours | Hours to days |
Severity | Can be life-threatening | Uncomfortable but not dangerous |
Amount | Tiny amounts trigger reaction | Often dose-dependent |
Testing | Blood IgE or skin prick | Elimination diet, breath tests |
Examples | Peanut anaphylaxis | Lactose intolerance |
This test is for true allergies (IgE-mediated), not intolerances.
When to Get Allergy Testing
Symptoms Suggesting Allergy
Hives, itching, or skin rashes
Swelling (lips, face, throat)
Runny nose, sneezing, congestion
Itchy, watery eyes
Wheezing or difficulty breathing
Digestive symptoms after eating
Anaphylaxis history
Benefits of Blood Testing Over Skin Prick
Can be done while on antihistamines
Suitable for eczema or skin conditions
No risk of allergic reaction during testing
Quantitative results (shows severity)
Comprehensive panels in one blood draw
Understanding Your Results
What Positive Results Mean
A positive specific IgE means you're sensitised to that allergen. This usually correlates with clinical allergy, but not always.
Your doctor will help you understand:
Which positives match your symptoms
Risk level for each allergen
Whether avoidance is necessary
If further testing (e.g., food challenge) is needed
What Negative Results Mean
Negative IgE makes true allergy unlikely, but:
Symptoms may be due to intolerance (not allergy)
Very recent sensitisation may not show yet
Some allergies aren't IgE-mediated
Managing Identified Allergies
Avoidance Strategies
Read food labels carefully
Inform restaurants of allergies
Control home environment (dust mite covers, air purifiers)
Keep pets out of bedrooms
Medical Management
Antihistamines for mild symptoms
Nasal corticosteroids for hay fever
Adrenaline auto-injector (EpiPen) for severe allergies
Immunotherapy (desensitisation) for some allergies
Book Your Allergy Test
Price: From £245
Results: 2-3 days
Doctor review: A doctor always reviews every result with interpretation
Fasting required: No
Phone: 020 3951 3429
FAQ
Can I take antihistamines before an allergy blood test?
Yes—unlike skin prick tests, blood tests aren't affected by antihistamines.
How accurate are allergy blood tests?
Very accurate for detecting sensitisation (>95%). Clinical correlation is needed to confirm actual allergy.
What's the difference between IgE and IgG food tests?
IgE tests detect true allergies. IgG tests are not recommended as they often show foods you've simply eaten, not allergies.
Can allergies develop at any age?
Yes—new allergies can develop at any age, and childhood allergies sometimes resolve.
Will this test diagnose all my allergies?
We test for the most common allergens. If you suspect something specific not on standard panels, let us know.
Blood Test London by The Wellness. Allergy blood testing from £245, results in 2-3 days.