Allergy tests in London with consultant review

At London Allergy and Immunology Centre, we offer consultant-led allergy assessment and testing in London, alongside selected remote allergy blood tests across the UK. Your symptoms and medical history guide the choice of tests and the interpretation of your results.

Whether you are concerned about food allergy, hay fever, animal allergy or contact dermatitis, an assessment helps establish which investigations may be useful and what your results mean for your care.

Choosing the right allergy tests

Allergy testing begins with a detailed medical history. Your consultant will consider what happened, how quickly symptoms developed, possible triggers and any previous treatment. A food and symptom diary can help where the cause is unclear.

A positive skin prick or specific IgE blood test indicates sensitisation; it does not, on its own, confirm a clinical allergy.
Results must be considered alongside your symptoms. Testing is recommended when it can help answer a clinical question or guide management.

Not every rash, episode of swelling or digestive symptom is caused by allergy. Urticaria and angioedema can have non-allergic causes, and allergy tests may not be needed in every case.

During your assessment, your consultant will:

• Review your symptoms, medical history and suspected triggers.
• Explain which tests are appropriate and their limitations.
• Interpret results in the context of your history.
• Discuss treatment, avoidance advice and follow-up where needed.

Types of allergy test available

Specific IgE blood tests

Specific IgE blood tests measure antibodies to selected allergens, such as milk, wheat, peanut, tree nuts, pollen, moulds and animal dander. They are sometimes referred to as RAST tests, although modern laboratory methods differ from the original RAST technique.

Testing can be arranged in clinic or, for suitable tests, through remote sampling. Drug allergy investigations require a separate specialist assessment; a blood test alone may not confirm or exclude a drug allergy.

Molecular allergy testing: ALEX and allergen components

Molecular allergy testing measures IgE to individual allergen components. ALEX testing includes a range of allergen extracts and molecular components in one blood sample.

In selected cases, component testing can help clarify cross-reactivity, pollen–food syndrome and sensitisation patterns involving foods, latex or occupational allergens. Your consultant will explain whether the additional information is relevant to your symptoms. No allergy test can reliably predict the severity of every future reaction.

Skin prick testing

Skin prick testing assesses immediate sensitisation to selected allergens. We perform this testing during consultations, with the skin response usually assessed after around 15–20 minutes.

Where appropriate, prick-to-prick testing with fresh foods may be considered. Please agree any items to bring with the clinic in advance.

Patch testing for contact allergy

Patch testing investigates delayed allergic contact dermatitis caused by substances such as metals, fragrances, preservatives and chemicals. It differs from skin prick testing and is not a routine test for immediate food allergy.

Allergens are applied to the skin and assessed over several days. The clinic will confirm the application appointment and the required return visits for readings.

Food and symptom diaries and supervised dietary assessment

For selected suspected food-related symptoms, a structured diary and a supervised elimination and reintroduction plan may help the assessment. This is tailored to the clinical history and is not required for everyone with eczema or digestive symptoms.

Avoid removing several foods from your diet without professional advice. If there is a risk of an immediate allergic reaction, reintroduction must follow the specialist’s instructions.

Intradermal testing

Intradermal testing is used in selected specialist allergy investigations, including some drug allergy pathways. A small amount of a carefully diluted test solution is injected into the skin under medical supervision. Your specialist will explain when this is appropriate.

Provocation and challenge tests

Specialist investigations may include oral food challenges, drug challenges, nasal provocation or conjunctival provocation testing. These procedures help answer specific diagnostic questions when the history and other tests are insufficient.

Challenge tests arranged through our service take place in hospital settings with trained staff and resuscitation equipment available. Do not attempt a food or drug challenge at home.

Occupational and specialist component testing

Selected investigations include occupational allergens, enzymes, latex components, alpha-gal and omega-5 gliadin. Testing for cross-reactive carbohydrate determinants (CCD) may help explain certain positive results. The choice of investigations depends on your exposure history and symptoms.

Remote allergy testing across the UK

Selected remote allergy blood tests are available across England, Scotland, Wales and Northern Ireland. For remote ALEX testing, a detailed online questionnaire provides information about your symptoms and medical history.

A consultant review of your results is included in the remote test price. Follow-up appointments can be arranged, and results can be communicated to your GP with your consent. Please check the service details for the sampling method, fees and what any additional appointment includes.

Remote blood sampling does not replace an examination or supervised skin testing when these are needed. Patients outside the UK should contact us before ordering to confirm availability and sample transport arrangements.

Allergy testing: frequently asked questions

Which allergy test do I need?

The most useful test depends on your symptoms, suspected trigger and timing of reactions. Your consultant may recommend skin prick testing, blood testing, patch testing or a different investigation. Sometimes no allergy test is needed.

Does a positive result mean I must avoid that food?

Not necessarily. A positive result can show sensitisation without clinical allergy. Discuss the result with your consultant before changing your diet, particularly if you currently eat the food without symptoms.

Should I stop antihistamines before testing?

Antihistamines can affect skin prick results. Ask the clinic for instructions before your appointment, as the advice depends on the medicine and the planned test. Do not stop prescribed medicines without appropriate advice.

How much do allergy tests cost?

Costs depend on the consultation and investigations required. Contact the clinic for current fees and confirmation of what is included before booking or ordering.

Further information:

NHS guidance on allergies

and

BSACI information on food allergy investigations
.