Frequently Asked Questions About Allergy Testing
Answers to the questions we’re asked most often about private allergy testing — remotely at home or in our London laboratory. Can’t find what you’re looking for? Get in touch and one of our specialist allergy consultants will help.
General
- Allergy testing looks for sensitisation – the presence of specific IgE antibodies your immune system has produced against a particular food or airborne protein.
- Intolerance is a different, non-immune mechanism. The intolerance tests we offer are genetic tests that detect a predisposition to digestive problems with lactose (milk sugar) and gluten (the protein in wheat, barley and rye).
- A positive allergy or intolerance result on its own is not a diagnosis – it always needs to be interpreted alongside your symptoms and history by a specialist consultant.
- Our specialist consultants test for a wide range of allergens, including food allergens (peanut, tree nuts, milk, egg, wheat, soya, fish and shellfish) and aeroallergens (pollen, house dust mites, pet dander and mould).
- Our most comprehensive option, the ALEX³ Allergy Test, screens up to 300 food and airborne allergens from a single sample.
- We also offer genetic intolerance testing for gluten and lactose when these are clinically indicated.
- IgE blood tests measure antibodies linked to immediate-type allergic reactions – the kind that can cause hives, swelling, wheeze or anaphylaxis within minutes to hours of exposure. This is the type of test we offer.
- IgG (sometimes marketed as “food sensitivity”) tests measure a different antibody that mainly reflects normal exposure to a food rather than allergy, and major allergy bodies advise against using IgG panels to diagnose food allergy.
- If you suspect a true allergy – especially one involving a rapid or severe reaction – an IgE test interpreted by a specialist is the appropriate route.
- Your consultant will advise how often retesting is useful, based on your age, symptoms and previous results.
- In children, sensitisation patterns can change as the immune system matures, so we usually suggest repeating every 3–5 years, or sooner if symptoms change.
- In adults, allergy profiles tend to be more stable; testing roughly every ten years is typical, though this can be more frequent if new symptoms develop.
- The ALEX³ Allergy Test is the latest generation of multiplex molecular allergy testing, screening up to 300 allergen extracts and individual molecular components – including airborne allergens, foods and insect venoms – from one sample.
- Because it tests at component level rather than whole-extract level, it can help distinguish a genuine primary allergy from cross-reactivity between related proteins (for example, between certain pollens and foods), which standard panels can miss.
- As with all blood-based allergy tests, results show sensitisation, not a confirmed clinical allergy. They are most reliable when reviewed alongside your symptom history by one of our specialist allergy consultants, which is included with every test.
- The test needs only a small blood sample, taken either by finger prick at home or venously in our laboratory, and antihistamines do not affect the result.
- Anaphylaxis is a medical emergency. Warning signs include difficulty breathing, swelling of the throat or tongue, a rapid heartbeat, a sudden drop in blood pressure or feeling faint, light-headedness, confusion, blue or pale skin or lips, and collapse or loss of consciousness.
- If you or someone else has these symptoms, call 999 or go to A&E immediately – do not wait for allergy test results. Book allergy testing once the person has recovered and been advised it is safe to do so.
There’s no minimum age for allergy testing. A parent or guardian can collect their child’s sample at home if they feel confident doing so; otherwise, we recommend it’s taken by a trained healthcare professional.
You can have the sample collected at our London laboratory or in one of our clinics for an additional fee. If you’re elsewhere in the UK, a local healthcare professional can collect the sample by finger prick, heel prick, or from a vein, whichever is most appropriate for your child’s age.
For suspected food allergy, testing is usually appropriate if you’ve had:
- a history of rashes or hives
- swelling of the lips, tongue, eyes or face
- feeling sick, vomiting or diarrhoea within minutes to 24 hours of eating – with or without exercise
- a reaction linked to non-steroidal anti-inflammatory drugs (aspirin etc.), sun exposure, alcohol, or a combination of these factors
For suspected respiratory or seasonal allergy, testing can help if you have:
- hay fever or asthma-type symptoms (wheezing, chest tightness, shortness of breath, cough) on exposure to allergens or at certain times of year
- itchy, red, watering eyes (conjunctivitis)
- a scratchy throat or an itchy, runny or blocked nose (allergic rhinitis)
For intolerance testing (a different mechanism from allergy), it’s worth considering if you have:
- bloating or abdominal distension after eating wheat, barley or rye (pasta, beer, lager etc.), in adults or children
- symptoms suggestive of coeliac disease/gluten intolerance, or of lactose intolerance after dairy
We generally don’t recommend allergy testing for recurrent spontaneous rashes or hives, or swelling that isn’t linked to a specific trigger, or unexplained tummy pain – these are better assessed in a consultation, as different investigations are usually needed. The same applies to persistent eczema or dermatitis, particularly around the mouth or eyes, where clinic-based assessment may be more appropriate than blood testing alone.
Symptoms vary depending on the allergen and how you’re exposed to it – a runny nose with pollen, a rash with skin contact, or nausea and swelling after eating a trigger food. If you experience a severe reaction, seek emergency medical attention first and arrange allergy testing once you’ve recovered.
The Test
- Yes. Complete our online questionnaire and we’ll post a home test kit to anywhere in the UK – England, Scotland, Wales or Northern Ireland.
- You collect a small finger-prick blood sample at home and return it to our accredited laboratory using the prepaid packaging provided.
- Prefer to have your sample taken professionally? You can also visit our London laboratory for a venous blood draw, or arrange collection with a local healthcare professional if you’re further away.
- Yes, the tests are very safe. There’s no fasting required and no need to stop taking antihistamines beforehand, since the test measures antibodies in your blood rather than a skin reaction.
- This is one practical advantage blood tests have over skin prick testing, which usually requires stopping antihistamines for several days first.
No. The remote kit uses a simple finger-prick lancet to collect a small capillary blood sample, which most people find no more uncomfortable than a brief pinprick. If a venous sample is needed (for example, for very young children or larger panels), this is taken quickly by a trained professional.
None beyond the brief, minor discomfort of the finger prick or blood draw itself. Unlike skin prick testing, there is no risk of triggering an allergic reaction during a blood test, so it’s a suitable option even for people with a history of severe reactions.
- There’s no lower age limit for allergy blood testing itself, but self-collection by finger prick at home isn’t suitable for children under 6.
- For babies, toddlers and younger children, the sample needs to be collected by a trained healthcare professional – either at our London laboratory (Monday–Friday 7am–7pm, Saturday 9am–5pm), or we can supply collection materials to a local healthcare provider if you’re at a distance from London.
- Once your sample reaches the laboratory, results are typically ready within 7–10 working days, and up to two weeks during busier periods.
- Every result is reviewed by one of our specialist allergy consultants alongside your questionnaire answers, so you receive a full written interpretation, not just a raw lab report.
Yes, blood-based allergy testing is safe during pregnancy, as it carries no risk of triggering a reaction. If you’re pregnant and have specific concerns about a suspected allergy, it’s worth mentioning this when you complete the questionnaire so your consultant can take it into account when reviewing your results.
Both methods detect sensitisation rather than confirming a clinical allergy outright, and each has its place. Skin prick testing is performed and read in person by a trained allergist and is well suited to inhaled allergens. Blood tests like ALEX³ aren’t affected by antihistamines or skin conditions such as eczema, can be done remotely, and are suitable for all ages, including infants. Your consultant will recommend the most appropriate approach – or a combination – based on your symptoms.
Ordering
Pricing depends on the test you choose. Our comprehensive ALEX³ Allergy Test (up to 300 allergens) and individual allergen panels are paid by credit/debit card after completing the questionnaire. Current prices are shown at checkout for each test – see the ALEX³ test page for the latest price, or contact us if you’d like a quote before ordering.
Complete our online questionnaire and make your payment – a test kit will be posted straight to your home anywhere in England, Scotland, Wales or Northern Ireland. If you’d prefer your sample taken in person, you can visit our accredited laboratory in London instead.
Remote finger-prick kits are limited by sample volume, so they generally cover up to 3 individual allergens, or the full ALEX³ panel ordered on its own. If you need a broader combination of individual tests, you can either place separate orders or visit our London laboratory, where a larger venous sample can cover any number of allergens in one visit.