Allergy Blood Tests
An allergy blood test measures allergen-specific IgE antibodies, the immune proteins behind allergic reactions, from a single venous sample. Sometimes still called a RAST test, it is processed by an accredited UK laboratory and every result is reviewed by a GMC-registered doctor. It is a practical way to investigate what you may be sensitised to, without stopping your antihistamines.
By Dr Maryam Attarzadeh, GMC-registered doctor and Medical Director, KONCEPT® Medical Clinic. Last reviewed July 2026. Next review January 2027.
Allergic reactions are driven by immunoglobulin E (IgE), a class of antibody your immune system makes against specific allergens. A blood test measures those antibodies directly in the laboratory, which is why it does not depend on your skin or your medication on the day.
When you become sensitised, your immune system produces IgE targeted at a particular allergen, for example cat dander or peanut. These antibodies circulate in the blood.
The lab measures how much IgE you carry to each chosen allergen, reported in kU/L. Higher levels indicate stronger sensitisation, though the number is not a measure of how severe a reaction would be.
A total IgE test measures your overall IgE. It helps interpret specific results and can be raised in allergy, eczema and some other conditions.
A GMC-registered doctor reviews the numbers against your history and sends a short outcome note. Sensitisation is only meaningful once placed alongside your symptoms.
These terms describe the same underlying idea, measuring IgE antibody, at different levels of detail. Knowing which is which helps you choose the right test.
| Test | What it measures | Best for |
|---|---|---|
| Specific IgE (formerly RAST) | IgE to one named allergen you choose, reported in kU/L. | A clear, single suspected trigger, or confirming one allergen. |
| Total IgE | The overall amount of IgE antibody in your blood. | Background context, monitoring, and interpreting specific results. |
| Component-resolved (ALEX Explorer) | IgE to hundreds of whole allergens and individual molecular components at once. | Several or unclear triggers, and telling genuine allergy from cross-reactivity. See the ALEX Allergy Explorer › |
RAST stands for radioallergosorbent test, the original method for measuring specific IgE. Modern laboratories, including the accredited UK lab we use, have replaced it with newer fluorescence and immunoassay techniques that are more sensitive and no longer use radioactivity. The name has stuck in everyday use, so if your GP mentions a “RAST test”, this is what they mean.
Specific IgE can be requested to a wide range of inhalant, food, venom and occupational allergens. The doctor advises which are worth checking based on your symptoms, rather than testing everything indiscriminately.
| Group | Typical allergens | Often relevant when |
|---|---|---|
| Inhalant (aeroallergens) | Grass and tree pollens, house dust mite, cat and dog dander, moulds. | Rhinitis, sneezing, itchy eyes, asthma-type symptoms, seasonal or year-round. |
| Food | Peanut, tree nuts, milk, egg, wheat, soya, fish and shellfish. | Reactions after eating, lip or mouth tingling, hives, gut symptoms. |
| Venom | Bee and wasp venom. | Significant reactions to stings. |
| Occupational / other | Latex and selected workplace allergens. | Symptoms linked to work or specific exposures. |
A raised specific IgE shows your immune system recognises an allergen. That is sensitisation.
Whether sensitisation matters depends on your story: what happens, how soon, and how consistently.
Specific IgE testing is a well established, reproducible laboratory measurement. Its usefulness depends on choosing the right allergens and reading the numbers in context. A blood test is a strong first-line investigation, not a standalone diagnosis.
The UK has one of the highest rates of allergic disease in the world, and it continues to rise. A measured, doctor-read result helps make sense of symptoms and point to the allergens worth investigating.
of UK adults live with at least one allergic condition.
of UK adults are affected by allergic rhinitis (hay fever).
rise in UK hospital admissions for serious allergic reactions over the past 20 years.
working days for most specific IgE results to return.
Sources: Allergy UK, Statistics and Figures; British Society for Allergy and Clinical Immunology (BSACI). Figures are UK population estimates, provided for context.
Every price is a single all-inclusive price that covers the venous draw, accredited UK laboratory processing, doctor review and a secure outcome note.
| Test | What you get | Price (all-in) |
|---|---|---|
| Individual Allergen (Specific IgE) | Specific IgE to one allergen you choose with the doctor. | £108 |
| Total IgE | Your overall IgE level, for context or monitoring. | £138 |
| ALEX Allergy Explorer component-resolved, hundreds of allergens | A broad screen in one sample. Full ALEX page › | £418 |
| Immunoglobulins (IgA, IgG, IgM) | Assesses overall immune function rather than allergy. | £168 |
One all-inclusive price covers your visit however many tests you book. If a detailed interpretation or a GP review is recommended afterwards, that is a separate booking: your NHS GP at no NHS charge, or a KONCEPT® GP consultation at £149.
| Allergy blood test (specific IgE) | Skin-prick test | |
|---|---|---|
| Sample | One venous blood draw. | Drops of allergen pricked into the skin of the forearm. |
| Antihistamines | No need to stop them, they do not affect the result. | Must usually be stopped for several days beforehand. |
| Timing of result | Laboratory result in 2 to 5 working days. | Read in clinic within about 20 minutes. |
| When it suits | Widespread eczema, dermographism, a history of severe reactions, or if stopping medication is difficult. | When an immediate in-clinic reading is preferred and skin is clear. |
Both are valid, and both measure sensitisation rather than proving clinical allergy on their own. A doctor can advise which route fits your situation.
Book online or by phone. A GMC-registered doctor reviews the request and helps target the right allergens for your symptoms.
An experienced practitioner takes one venous sample in the Kingston clinic, usually 10 to 15 minutes. No need to stop antihistamines.
Your sample is processed to the same standards used by the NHS, measuring specific and, where requested, total IgE.
Most results in 2 to 5 working days, with a short doctor-reviewed note sent securely to your email. For a detailed interpretation, see your NHS GP or a KONCEPT® GP (£149).
There is no special preparation and no fasting. Keep taking your usual medicines, including antihistamines, unless a clinician tells you otherwise. If you have recently had a severe allergic reaction, seek urgent medical care first, testing is for investigation over time, not for an emergency.
NHS allergy care, through your GP and specialist allergy clinics, remains the right route for many people, particularly anyone who has had a severe reaction. KONCEPT® offers specific IgE testing directly, without referral, with a doctor to review the result against your history. With your written consent we share a clinical summary with your NHS GP, and we signpost to specialist allergy services where that is the appropriate next step.
KONCEPT® Medical Clinic offers doctor-reviewed allergy blood tests, specific IgE and total IgE, for patients across the KT and SW postcodes without a GP referral. People book from Kingston upon Thames, Surbiton, New Malden, Wimbledon, Richmond, Putney, Teddington, Hampton, Esher and Twickenham. The clinic is at 46 to 48 Wood Street, opposite Kingston Station.
It suits anyone searching for an allergy blood test, a RAST test, a specific IgE or IgE blood test, or a private allergy test near me in Kingston, Surrey or South West London. Book online or call 020 8129 1011.
The main allergy blood test measures allergen-specific IgE. It was historically known as a RAST test (radioallergosorbent test); modern laboratories use newer immunoassay methods but the term RAST is still widely used. A total IgE test measures the overall level of IgE antibody in the blood.
Specific IgE blood tests are a well established, reproducible way to measure sensitisation. A positive result shows your immune system has made IgE to an allergen, but it does not on its own confirm a clinical allergy, which is why the result is always read by a doctor alongside your symptoms and history. Accuracy varies by allergen, so the doctor interprets the numbers in context rather than as a simple yes or no.
No. Unlike a skin-prick test, an allergy blood test is not affected by antihistamines, so there is no need to stop them beforehand. This is one reason a blood test is useful for people who cannot easily come off their medication.
Most results are back within 2 to 5 working days. A GMC-registered doctor reviews the result and sends a short outcome note securely to your email.
Yes. Specific IgE can be measured to a wide range of allergens, including foods (such as peanut, milk, egg, wheat and shellfish) and inhalants (such as cat and dog dander, house dust mite, pollens and moulds). The doctor advises which allergens are worth testing based on your symptoms.
Sensitisation means your immune system has made IgE to an allergen and can be detected on a blood test. Allergy means you also get symptoms when exposed to it. Many people are sensitised without being clinically allergic, so a positive test is interpreted against your history before any conclusion is drawn.
No. Hair-analysis tests and IgG food intolerance tests are not validated ways to diagnose allergy and are not recommended by UK allergy bodies. A true allergy blood test measures allergen-specific IgE. To investigate a possible allergy, specific IgE testing or a supervised clinical assessment is the recognised route.
An individual allergen specific IgE test is £108 all-in, a total IgE test is £138 all-in, and the broad component-resolved ALEX Allergy Explorer is £418 all-in. Each price is a single all-inclusive price that covers your whole visit. If a detailed interpretation or GP review is needed afterwards, that is a separate booking: your NHS GP at no NHS charge, or a KONCEPT® GP consultation at £149.
Both measure IgE sensitisation. A blood test needs only one venous sample, is not affected by antihistamines, and is preferred when someone has widespread eczema, a history of severe reactions, or cannot stop their medication. Skin-prick testing gives immediate results in clinic. The right choice depends on your situation, and a doctor can advise.
Genuine reviews from patients who tested at KONCEPT®, drawn from our Google Business Profile and verified-patient reviews.
“I came here for some blood tests and travel vaccinations. Really impressed by the blood test results turnaround, came in a couple days. As a Kingston local it is great to have the clinic in easy reach.”
“I went in for a blood test a couple days ago which was such a smooth and pleasant experience and I received my results back the next day. A super quick turnover time which is just what I needed.”
“It was quick, professional and I did not feel rushed. Everyone was really nice and welcoming, and made me feel at ease straight away. Would definitely recommend.”
Genuine reviews from our Google Business Profile and verified-patient reviews. Individual experiences vary. Read more reviews on Google ›
Specific IgE and total IgE blood tests from £108 all-in, a single all-inclusive price per visit. Same-day, evening and Saturday appointments available. No GP referral needed, and no need to stop your antihistamines. Doctor-reviewed result, sent securely to your email.
Serving Kingston upon Thames and the surrounding KT, SW and TW catchment, including Surbiton, Wimbledon, Richmond, Putney, Teddington, New Malden, Esher and Twickenham.
This page is for information only and is not a substitute for medical advice. An allergy blood test measures IgE sensitisation and is interpreted by a qualified clinician alongside your symptoms and history. A result does not on its own diagnose or exclude an allergy, or predict how you will react. Anyone who has had a severe allergic reaction should seek urgent medical care.