Contents
Do You Recognise These Questions?
Many people across the UK live with unexplained rashes, digestive symptoms, breathing difficulties, nasal congestion, or persistent fatigue — yet never receive a clear diagnosis. Without knowing the cause, it is very difficult to know what to do next.
“Is this a real allergy, or something else?”
“Which food or allergen is actually causing this?”
“Could this happen again — and could it be serious?”
“Am I avoiding foods I don’t actually need to avoid?”
The ALEX molecular allergy test was designed to answer these questions accurately — testing 300 allergens and individual allergen proteins from a single small blood sample, with all results reviewed and explained by a qualified consultant allergist.
What Is the ALEX Molecular Allergy Test?
The ALEX (Allergy Xplorer) is an advanced molecular allergy blood test developed by MacroArray Diagnostics (MADx) in Vienna, Austria. The current version — ALEX³ — simultaneously measures allergen-specific IgE (sIgE) antibodies to over 300 allergens and molecular allergen components from a single small blood sample using chip-based macroarray technology.
Unlike older tests that check one allergen at a time, ALEX³ produces a complete allergy sensitisation profile in one step. Importantly, it does not just test allergen extracts — it also identifies the specific molecular proteins (components) within each allergen source that are responsible for your immune response. This extra level of precision is what distinguishes ALEX³ from standard allergy blood tests.
ALEX³ is used in specialist allergy clinics across more than 90 countries worldwide. Its third-generation panel was redesigned in 2025 using data from nearly 400,000 real-world test results, adding 52 new allergens including alpha-gal (the tick-triggered red meat allergy marker), new crustacean components, cyclophilins, and additional venom components.
The ALEX³ biochip — 300 allergens and components analysed from one sample
Recommended by current allergy guidelines
The EAACI 2025 guidelines on IgE-mediated food allergy confirm that component-resolved diagnostics (CRD) — the methodology at the heart of ALEX³ — should now be used as standard practice to distinguish genuine allergy from cross-reactive sensitisation, and to guide immunotherapy selection. ALEX³ delivers this in clinical practice.
Watch: How the ALEX Molecular Allergy Test Works
The video below explains how the ALEX molecular allergy test analyses 300 allergens from a single blood sample, and how the results help identify the specific proteins driving your allergy symptoms.
ALEX Molecular Allergy Test — analysing 300 allergens and components from one blood sample.
The Technology Behind ALEX³
Biochip macroarray
300 allergens and molecular components are individually immobilised on a single chip. When the patient’s blood sample is applied, any IgE antibodies present bind to their corresponding allergen spots — producing a complete sensitisation map in one assay run.
Quantitative results
sIgE binding is detected and quantified using an enzyme-linked fluorescent readout, producing precise concentration values (kU/L) for each allergen simultaneously. Total IgE is also measured in the same sample.
CCD inhibitor — fewer false positives
Cross-reactive carbohydrate determinants (CCDs) are shared sugar structures that can cause false-positive IgE results in standard tests. ALEX³ incorporates a built-in CCD inhibitor to suppress these clinically irrelevant signals, improving diagnostic specificity significantly.
Globally validated panel
ALEX³’s panel was designed using real-world data from nearly 400,000 ALEX2 tests. Allergens with low prevalence were removed; 52 clinically important new allergens were added. Results are stored on a GDPR-compliant cloud server for quality assurance and postmarket surveillance.
What Does ALEX³ Test?
ALEX³ covers the full range of clinically relevant allergens for both adults and children in the UK. The panel includes allergen extracts (whole allergen sources) and individual molecular components (the specific proteins within them).
Food Allergens
- Peanut (including Ara h 1, 2, 3, 6, 8, 9)
- Tree nuts: hazelnut, walnut, cashew, almond, pecan, pistachio, Brazil nut, pine nut, coconut
- Milk (casein, whey proteins including Bos d 4, 5, 8)
- Egg (Gal d 1–4: ovomucoid, ovalbumin)
- Wheat, soya, sesame
- Fish (cod Gad c 1, salmon, tuna) and shellfish (shrimp, crab, tropomyosin)
- Fruits: apple, peach, kiwi, strawberry, mango
- Alpha-gal (α-Gal) — red meat / tick allergy
Pollens
- Grass pollens: Timothy (Phl p 1, 4, 5, 6, 7, 11, 12)
- Tree pollens: birch (Bet v 1, 2, 4), alder, hazel, oak
- Weed pollens: mugwort (Art v 1, 3), ragweed, plantain
- Olive, cypress, plane tree
- Maize pollen (new in ALEX³)
Indoor / Environmental
- House dust mite: Dermatophagoides (Der p 1, 2, 10, 21, 23)
- Cat (Fel d 1, 4), dog (Can f 1, 2, 3, 5), horse
- Moulds: Alternaria (Alt a 1), Aspergillus, Cladosporium
- Cockroach, storage mites
- Golden hamster (new in ALEX³)
Venoms & Other
- Bee venom (Api m 1, 4, 10)
- Wasp venom (Ves v 1, 5)
- Bald-faced hornet venom (new in ALEX³)
- Latex (Hev b 1, 3, 5, 6, 8, 11)
- Total IgE
This is a representative selection only. The full ALEX³ panel lists 300+ allergens and components. View the full allergen list here →
Why Knowing the Specific Protein Matters — Allergy vs Cross-Reactivity
Many allergens share similar proteins, meaning the immune system sometimes reacts to one because it looks like another. This is called cross-reactivity. On a conventional allergy blood test, a cross-reactive result looks identical to a genuine allergy — both produce a “positive”. Yet the clinical implications are completely different.
ALEX³ identifies not just what you react to, but which specific protein is causing the reaction. This is the difference between:
True Primary Allergy — High-Risk Proteins
Species-specific proteins that cannot be destroyed by cooking or digestion. Reactions occur consistently. Risk of severe reactions and anaphylaxis. Requires strict avoidance and often an adrenaline auto-injector.
Examples: Ara h 2 (peanut), Gal d 1 (egg), Api m 1 (bee venom), Der p 1 (dust mite)
Cross-Reactive Sensitisation — Usually Low Risk
Proteins shared between a pollen and a food, or between different pollen families. Usually heat-labile (destroyed by cooking). Reactions typically limited to mild oral tingling. Rarely systemic. Strict avoidance often unnecessary.
Examples: Ara h 8 (peanut, birch-linked), Bet v 1 (birch / oral allergy syndrome), profilins
Why this matters for you: Without molecular testing, someone whose positive peanut IgE is driven by Ara h 8 (birch cross-reactivity) may be incorrectly placed on a strict peanut-free diet — with all the anxiety, social restriction, and nutritional impact that involves — when in reality they have oral allergy syndrome and could safely eat well-cooked or processed peanut. Conversely, identifying Ara h 2 positivity confirms genuine peanut allergy with anaphylaxis risk, ensuring that person carries an adrenaline auto-injector. The correct answer matters enormously.
Who Is ALEX³ Most Helpful For?
ALEX³ is not the right test for every situation — your consultant will advise whether it is the most appropriate choice for you. It is particularly valuable for:
Multiple suspected allergies
Reactions to many different foods or environmental triggers — ALEX³ maps the whole picture in one test instead of repeated separate blood draws.
Unclear or conflicting previous tests
Positive results from previous tests that do not match your actual symptoms — CRD clarifies which positives are genuinely relevant and which are cross-reactive artefacts.
Peanut allergy severity assessment
Ara h 2 on ALEX³ is the most accurate marker for confirming true peanut allergy and estimating reaction risk — essential for auto-injector decisions and OIT candidacy.
Hay fever and immunotherapy planning
Identifying the primary pollen sensitiser (grass vs birch vs other) ensures the most effective immunotherapy allergen is selected — and avoids ineffective treatment.
Bee or wasp venom allergy
When both bee and wasp test positive on standard tests, ALEX³ CRD identifies whether both venoms are genuinely implicated or whether CCD cross-reactivity is the cause — directing the correct venom immunotherapy.
Delayed reactions to red meat
Alpha-gal syndrome — the tick-triggered delayed red meat allergy — is now testable within the ALEX³ panel, important for anyone experiencing unexplained symptoms 3–6 hours after eating beef, pork, or lamb.
Children & families
A single small blood sample tests hundreds of allergens relevant to paediatric allergy — avoiding repeated phlebotomy while providing the molecular detail needed to manage food allergies safely in childhood.
How ALEX³ Changes Clinical Decisions — Real Examples
The Testing Process — Step by Step
Medical questionnaire & consultant review
Complete a detailed medical questionnaire about your symptoms, reactions, dietary habits, and prior test results. An allergy consultant reviews this information to confirm ALEX³ is the most appropriate test for your situation and to guide which results will be most clinically meaningful.
Blood sample collection
A small blood sample is collected — either at one of our London clinics by a trained nurse, or via our at-home postal kit (see below). Antihistamines do not need to be stopped before a blood test. No fasting is required. Finger-prick testing is suitable for adults and children over 6; children under 6 or those who prefer a venous draw can attend a local phlebotomy service.
Laboratory analysis — 5–7 working days
Your sample is sent to our specialist laboratory for fully automated ALEX³ processing. The macroarray chip is run to generate quantitative sIgE results for all 300 allergens, with built-in CCD inhibition applied. Results are securely stored on the MADx GDPR-compliant cloud server.
Consultant review — the most important step
Your results are reviewed and clinically interpreted by a consultant allergist — not by an automated report alone. Positive results are assessed for clinical significance. Cross-reactive positives are distinguished from genuine allergies. A personalised written summary and management plan is produced. Results are available securely via the Carebit patient portal.
Results consultation & treatment plan
A follow-up consultation (in-clinic or video) reviews your results in full — what they mean, what you need to avoid, whether further investigations are needed (food challenge, skin prick testing), and whether treatment options such as immunotherapy or emergency medication are appropriate. A clinic letter is sent to you and, with consent, to your GP. Consultations and prescriptions are subject to a separate fee.
ALEX³ At-Home Postal Test — Available Anywhere in the UK
Not based in London? You can access the same ALEX³ molecular allergy test from anywhere in England, Scotland, Wales, or Northern Ireland via our at-home postal testing service.
❶ Order online
Purchase the ALEX³ test and a home sample collection kit is posted to you with full instructions.
❷ Collect sample
Simple finger-prick at home (or local phlebotomy for young children or those preferring a venous draw).
❸ Post sample
Return via pre-paid, temperature-controlled packaging. Processed within 5–7 working days of receipt.
❹ Consultant review
Results reviewed by a consultant; video consultation to discuss findings and next steps.
Allergy vs Intolerance — What Is the Difference?
Symptoms of allergy and intolerance can sometimes look similar, but they are caused by different mechanisms — and this matters for testing and treatment.
IgE-Mediated Allergy
- Involves the immune system — the body produces IgE antibodies to a specific allergen
- Reactions typically develop within minutes to 2 hours of exposure
- Can cause urticaria, angioedema, asthma, or anaphylaxis
- Even small amounts of the allergen can trigger a reaction
- ALEX³ detects IgE-mediated allergy
Food Intolerance
- Does not involve IgE antibodies — the immune mechanism is absent or different
- Symptoms often affect digestion and tend to appear later (hours to days)
- Examples: lactose intolerance (enzyme deficiency), gluten sensitivity, FODMAP sensitivity
- Reactions often dose-related — small amounts may be tolerated
- Not detected by ALEX³ — requires separate investigation
Important: Many people remove foods from their diet without a clear diagnosis — sometimes after unvalidated IgG “intolerance” tests that are not recommended by EAACI, BSACI, or NICE. These tests measure normal exposure responses, not allergy or intolerance. Unnecessary dietary restriction can cause nutritional deficiencies and anxiety. Always speak with a qualified healthcare professional before making long-term dietary changes based on a test result.
Frequently Asked Questions
Related Pages
Important Notice
ALEX³ results must be interpreted by a qualified allergy consultant in the context of a full clinical history. A positive sIgE result does not confirm clinical allergy without specialist review. Consultations and prescriptions are subject to a separate fee. In a medical emergency, call 999.
References
- Sturm GJ, et al. Big data-driven evolution of a diagnostic multiplex IgE-test: enhancing accuracy and efficacy in allergy diagnostics. Allergy. 2025. PMC12072476.
- Santos AF, Riggioni C, et al. EAACI Guidelines on the Management of IgE-mediated Food Allergy. Allergy. 2025;80(1):1–28. doi:10.1111/all.16345
- Hemmings O, Du Toit G, Radulovic S, Lack G, Santos AF. Ara h 2 is the dominant peanut allergen despite similarities with Ara h 6. J Allergy Clin Immunol. 2020;146(3):621–631.
- MacroArray Diagnostics (MADx). ALEX³ Allergy Xplorer — product information. Vienna, Austria. 2025. www.macroarraydx.com
- Commins SP, et al. Delayed anaphylaxis after consumption of red meat related to IgE antibodies specific for galactose-α-1,3-galactose. J Allergy Clin Immunol. 2009;123(2):426–433.
Page reviewed: June 2026 | London Allergy and Immunology Centre | privateallergy.uk