Part of the London Allergy Clinic
Diagnosis & Specialist Care of Allergy & Clinical Immunology - Since 1982
An allergy blood test measures IgE, the antibody your immune system makes when it has become sensitised to an allergen. It is one of the two main ways to test for allergy; the other is a skin prick test.
This page explains how an allergy blood test works, what a result can and can’t tell you, and three ways to have the ALEX³ Allergen Panel Test. For a wider view, see our overview of allergy testing →
How an allergy blood test works
A small blood sample goes to a laboratory, which measures the amount of IgE to specific allergens, such as pollens, house dust mite, pets or foods.
Some blood tests look at one allergen. If you have one specific question, such as whether you react to cat or dog, a single-allergen blood test for airborne allergens is available at Wimpole Street from £120 through The London Allergy Clinic.
The ALEX³ Allergen Panel Test is one of the most comprehensive IgE panels available. It measures IgE to 300 allergens (82 whole allergens and 218 molecular components) from a single blood sample.
Molecular components are individual proteins within an allergen source.
Antihistamines do not affect allergy blood tests, so there is no need to stop them. If you have had an allergic reaction, we advise waiting at least 4 weeks before testing.
What a result can and can’t tell you
A blood test can show sensitisation, meaning your immune system has made IgE to an allergen. Sensitisation is not the same as allergy. Allergy means you have symptoms when you are exposed to the allergen, and some people have IgE to an allergen without ever reacting to it.
So a result cannot confirm an allergy on its own. A positive result suggests a higher likelihood of a reaction but does not prove one, and a negative result does not always rule an allergy out. Allergy is diagnosed from your symptoms and history, with tests supporting that picture. NICE guidance on food allergy in children and young people says test results should be interpreted in the context of the person’s history. This is why specialist interpretation of test results is important.
Blood tests sold to diagnose food intolerance are different. The NHS says they are not recommended because there is limited evidence that they give accurate results, and NICE advises against serum-specific IgG testing in the diagnosis of food allergy. It is super important to know what test you are taking, and whether there is any evidence to support its validity, before making your purchase. We try to emphasise the difference between reliable and unreliable tests to ensure patients can make an informed and worthwhile choice.
Once you have results, The London Allergy Clinic’s guide to understanding allergy blood test results explains grades and kU/L.
AT HOME
£350
Test only
You collect a small blood sample from a finger prick at home, which takes about 15–20 minutes, and post it to the UKAS-accredited laboratory using the prepaid return.
It is suitable for adults and for children from 18 months.
Results are emailed within 1–2 working days of the laboratory receiving your sample.
Free next-day delivery included
Pre-paid return postage included
Suitable from 18 months
Home Test
NO APPOINTMENT NEEDED
Three ways to have the ALEX³ blood test
IN PERSON
At Wimpole Street
£520
Test and phlebotomy included
A healthcare professional takes the blood sample at our Wimpole Street partner location in central London.
Testing times are Monday to Friday 7am–7pm, Saturday 7am–1pm and Sunday 8am–11am. Same-day testing is available.
You book with the clinic by phone, WhatsApp or email, Monday to Saturday 9am–7pm.
Results by email within 2–3 working days. No doctor is involved, so your results are not interpreted for you.
During your consultation (adults)
£410
For the test, plus £350 consultation fee
A doctor takes your allergy history, takes the blood sample during your appointment, and adds their interpretation of your results to your clinic letter.
First consultations last up to an hour. Results arrive within 1–2 working days.
Blood taken by Dr Arumugakani, an experienced phlebotomist
Your results interpreted in your clinic letter
£110 saving on the test compared to testing in person without a consultation
For young children, the sample may need to be taken at Wimpole Street (£520) instead of during the consultation — the doctor will confirm at the appointment, before you pay for any testing.
Children are seen by our consultant paediatric allergists, Dr Emily Derrick and Dr Tammy Rothenberg, at Marylebone, in person or by video. See our children's allergy services,
All three routes test the same ALEX³ panel. They differ in who takes the sample and whether a doctor is involved.
Which route is right for you?
Home kit: you would like a comprehensive result and are happy to collect the sample yourself.
In person: you would rather a professional takes the sample, without seeing a doctor.
With a consultation: you would like a doctor to interpret your results, or you have questions - for example regarding reintroduction of a food previously eliminated, or worries about a serious reaction.
GOOD TO KNOW
Frequently Asked Questions
