Comprehensive Allergy Screening in London: Is the ALEX Test Right for You?

What Is the ALEX Allergy Test?

The ALEX (Allergy Explorer) test is a comprehensive allergy screening blood test that analyses your immune response to nearly 300 allergen extracts and molecular allergen components in a single blood sample. Unlike traditional allergy testing methods that assess one allergen at a time, the ALEX test provides a broad-spectrum allergy profile, making it one of the more comprehensive allergy blood tests available in the UK today.

For individuals living in London who experience unexplained symptoms that may be linked to allergic responses — such as persistent skin irritation, digestive discomfort, or respiratory difficulties — comprehensive allergy screening in London through the ALEX test can offer valuable insight without the need for multiple separate appointments.

At Private Blood Tests London, our nurse-led clinic offers the ALEX allergy test as part of our commitment to accessible, professional health screening. We provide testing and detailed reporting so you can take your results to an appropriate healthcare professional for further guidance.

How Does the ALEX Test Work?

The ALEX test works by measuring specific IgE (Immunoglobulin E) antibodies in your blood. IgE antibodies are produced by your immune system in response to substances it perceives as harmful — these substances are known as allergens.

A small blood sample is taken at the clinic by one of our qualified nurses. This sample is then analysed against a comprehensive panel that includes:

Food allergens — milk, eggs, wheat, nuts, shellfish, soya, and many more

Pollen allergens — grass, tree, and weed pollens common across the UK

Animal allergens — cat, dog, horse, and other animal dander

Insect allergens — bee venom, wasp venom

Mould allergens — Aspergillus, Alternaria, Cladosporium

Dust mite allergens — a common cause of indoor allergic responses

Latex and occupational allergens

The test identifies not only whole allergen extracts but also individual molecular components. This molecular-level analysis can help differentiate between a genuine primary sensitisation and a cross-reactivity — information that may be particularly useful when discussed with an allergy-focused healthcare professional.

Practical Insight: Because the ALEX test screens nearly 300 allergens simultaneously, it can sometimes highlight sensitivities that might not have been considered through standard single-allergen testing approaches.

ALEX Test vs Traditional Allergy Testing: A Comparison

Understanding the differences between allergy testing methods can help you decide which screening approach may suit your needs.

Feature	ALEX Allergy Test	Traditional Skin Prick Test	Single Allergen IgE Blood Test
Number of allergens tested	~295 allergens and components	Typically 10–40	1 per test
Sample type	Blood sample	Skin exposure	Blood sample
Molecular component analysis	Yes	No	Limited
Cross-reactivity identification	Yes	No	No
Suitable if taking antihistamines	Yes	May affect results	Yes
Single appointment	Yes	May require follow-up	Multiple tests needed
Available privately in London	Yes	Varies	Yes

Practical Insight: One notable advantage of blood-based allergy screening is that antihistamine use does not typically interfere with results, whereas skin prick testing may require you to stop antihistamines beforehand.

Who Should Consider the ALEX Allergy Test?

The ALEX test may be worth considering if you are experiencing symptoms that could potentially be linked to allergic sensitisation. You may wish to consider comprehensive allergy screening if you experience:

Persistent or seasonal nasal congestion and sneezing that may suggest environmental allergen exposure

Skin reactions such as hives, eczema flare-ups, or unexplained itching

Digestive symptoms including bloating, discomfort, or nausea after eating certain foods

Respiratory symptoms such as wheezing or chest tightness in specific environments

Reactions after insect stings that seem disproportionate

A family history of allergic conditions and a desire to understand your own sensitisation profile

Multiple suspected allergies where single-allergen testing would be time-consuming and costly

The test is suitable for adults and children, making it a practical option for families in London seeking a broad overview of potential allergen sensitivities.

Practical Insight: If you have been managing symptoms for some time without clarity on what may be contributing to them, an allergy profile can sometimes provide useful information to discuss with your healthcare provider.

What Do ALEX Test Results Mean?

Your ALEX test results will show IgE antibody levels for each allergen and molecular component tested. Results are typically categorised by level of sensitisation:

Negative / No sensitisation detected — no measurable IgE response to the allergen

Low sensitisation — a mild IgE response that may or may not be clinically relevant

Moderate sensitisation — a notable IgE response that may warrant further discussion with a healthcare professional

High sensitisation — a strong IgE response that can suggest a significant allergic sensitisation

It is important to understand that a positive IgE result indicates sensitisation, not necessarily clinical allergy. Some individuals may show IgE antibodies to certain allergens without experiencing symptoms upon exposure.

We provide a detailed, clearly formatted report with your results. We always recommend sharing your report with a qualified healthcare professional who can interpret the findings in the context of your symptoms and medical history.

Practical Insight: Understanding the difference between sensitisation and clinical allergy is essential. Your results are a valuable tool for informed conversations with medical professionals, rather than a standalone diagnosis.

How Often Should You Consider Allergy Screening?

There is no single guideline on how frequently allergy screening should be repeated, as this depends on individual circumstances:

First-time screening — if you have never had a comprehensive allergy profile, a baseline test can provide a useful reference point

Changing symptoms — if your symptoms change, worsen, or new suspected triggers emerge, repeat screening may offer updated information

Children and adolescents — allergy profiles can evolve during childhood and adolescence, so periodic screening may sometimes be considered

Post-lifestyle changes — significant dietary changes, relocation, or new environmental exposures may warrant reassessment

Allergy Screening in London: Why Choose Private Testing?

Accessing comprehensive allergy screening privately in London offers several practical benefits:

Reduced waiting times compared to NHS referral pathways for allergy services

Broad-spectrum testing in a single appointment

Convenient central London location at our nurse-led clinic

Detailed reporting that you can share with any healthcare professional

The NHS provides excellent allergy services, but referral pathways can sometimes involve extended waiting periods, particularly for non-urgent cases. Private allergy blood testing can complement NHS care by providing timely results.

If you are exploring other health screening options alongside allergy testing, you may find our full range of allergy tests helpful.

If you are considering a broader health check, you may also find our guide on understanding your bone screen results useful, as mineral balance and immune health often overlap in ways that surprise many patients. For a wider perspective on how private testing fits into proactive healthcare, our article on why Londoners are choosing private blood tests explores the practical benefits of accessible screening.

Frequently Asked Questions

What does the ALEX allergy test include?

The ALEX allergy test screens for approximately 295 allergen extracts and molecular components in a single blood sample. It covers food allergens, pollen, animal dander, insect venom, mould, dust mites, and latex. This comprehensive allergy screening approach provides a broad IgE sensitisation profile, offering more detail than standard single-allergen blood tests.

Is the ALEX test suitable for children?

Yes, the ALEX test is suitable for children as well as adults. Because it requires only a small blood sample, it can be a practical alternative to skin prick testing, which some children may find uncomfortable.

Do I need to stop taking antihistamines before the test?

No. Unlike skin prick testing, blood-based allergy screening such as the ALEX test is not typically affected by antihistamine medication. You can generally continue your usual medications before attending your appointment.

How long does it take to receive ALEX test results?

Results are typically available within 7–10 working days, depending on laboratory processing times. Once ready, your detailed report will be provided to you in a clear, accessible format. We recommend reviewing your results with a qualified healthcare professional.

Can the ALEX test diagnose a food allergy?

The ALEX test measures IgE sensitisation, which can indicate an immune response to specific food allergens. However, sensitisation alone does not confirm a clinical food allergy. The results are best interpreted by an experienced healthcare professional.

What is the difference between allergy and intolerance testing?

Allergy testing, such as the ALEX test, measures IgE antibody responses — these are immune-mediated reactions. Food intolerance testing typically measures IgG antibodies and relates to non-immune-mediated responses that may cause delayed symptoms such as bloating or discomfort.

How is the blood sample taken for the ALEX test?

A qualified nurse at our clinic will take a small venous blood sample from your arm. The procedure is straightforward and typically takes only a few minutes.

Can I use my ALEX test results with my NHS GP?

Absolutely. Your results report is designed to be shared with any healthcare professional, including your NHS GP or a private allergy specialist.

Is comprehensive allergy screening in London available without a GP referral?

Yes. At Private Blood Tests London, you can book the ALEX allergy test directly without requiring a GP referral. Our nurse-led service is designed to make health screening accessible and convenient.

About This Article

This article has been produced by the clinical content team at Private Blood Tests London and is intended for educational and informational purposes only. All content is written in line with UK medical editorial best practice and complies with GMC advertising guidance, CQC patient communication standards, and ASA guidelines.

Private Blood Tests London is a nurse-led clinic providing testing and reporting services only. We do not offer diagnoses, prescriptions, or treatment.

*Written: 18 March 2026 | Review date: 18 March 2027*

*This article is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Individual symptoms, health concerns, or test results should always be assessed by an appropriately qualified healthcare professional. Private Blood Tests London provides testing and reporting services only. No guarantees regarding health outcomes are made or implied.*