Allergy
Children's allergy testing and assessment
Written by Dr Martin Gray, Consultant Paediatrician, FRCPCH · GMC 4013396
Clinically reviewed by Dr Margarita Burmester, Consultant Paediatrician, FRCPCH · GMC 3332672 · Last reviewed 12 October 2026
Most parents who come to us about allergy have been going round in circles for a while. A rash after a meal that nobody could explain. One frightening reaction, never repeated, and a food the whole family now avoids. A suggestion to keep a food diary and come back in six weeks. Or a list of avoided foods that has quietly grown to eleven, with no real certainty that any of them was ever the problem.
Allergy in children is genuinely hard to pin down, and the uncertainty is its own burden — it changes how a family shops, eats, travels and relaxes. A structured first assessment is usually what cuts through it.
If your child is reacting now
Call 999 if your child:
has sudden swelling of the lips, mouth, throat or tongue
is breathing very fast, or struggling to breathe
has a tight throat, or is struggling to swallow
has skin, lips or tongue turning blue, grey or pale
becomes suddenly confused, drowsy or dizzy
is limp, floppy, or not responding as they normally would
If your child has an adrenaline auto-injector, use it first, then call 999. Lie them down and raise their legs — if breathing is difficult, let them sit up instead. Do not let them stand or walk, even if they seem to improve. If there is no improvement after 5 minutes, use a second auto-injector.
Bright Futures Health provides planned appointments. We cannot assess a reaction that is happening now.
What we are, and what we are not
We would rather be straightforward about this, because it affects whether an appointment with us is a good use of your time.
We are general paediatricians, not paediatric allergists. Dr Martin Gray and Dr Margarita Burmester are both consultant paediatricians with over thirty years of experience each, and allergy is among the concerns we see most often in general paediatric practice. We provide the initial assessment: a structured, unhurried, allergy-focused history and examination, skin prick testing arranged with our allergy nurse specialist where it will help, and an honest answer about what is most likely going on.
For a great many children that is the whole answer — and often the answer is that this is not allergy, and a family stops avoiding foods they never needed to avoid.
Where a specialist opinion is needed, we say so and arrange it. Some children need a paediatric allergist: someone who supervises food challenges and manages immunotherapy. When your child meets the criteria for that, our job is to recognise it at the first appointment and refer you on with a clear account of what we found.
We would rather tell you on day one that you need someone else than keep you in a holding pattern.
Three questions that change the answer
Allergy assessment looks mysterious from the outside. It mostly is not. A handful of details do most of the diagnostic work, and it is worth knowing which — because it tells you what to notice before you ever see a doctor.
01
How long after eating did it start?
Minutes points one way; six hours points somewhere quite different. Immediate reactions — within minutes to two hours — suggest the IgE-mediated allergy most people mean by the word. Symptoms appearing many hours later, usually in the gut or the skin, suggest a different mechanism entirely, investigated differently and not detectable by a skin prick test at all. The clock is the single most useful thing you can tell us.
02
Has it happened every time?
A food that causes a reaction once and is then eaten uneventfully twenty times is rarely the culprit. Reproducibility is what separates genuine allergy from coincidence — and coincidence is common, because small children eat frequently and catch viruses frequently, and the two overlap constantly.
03
What else was happening that day?
A viral rash, a hot bath, exercise, a new washing powder, teething, a first taste of something strongly flavoured. Many “reactions” turn out to have an explanation sitting right beside the food, which nobody examined because the food was the obvious suspect.
If you can answer those three before your appointment — ideally with photographs taken at the time — you will have done more for the diagnosis than any test will.
What the assessment involves
The most useful diagnostic tool in childhood allergy is a careful history. That is not us being cautious: it is what NICE guideline CG116 sets out as the foundation of assessment, and no test replaces it.
We go through what happened and when, the pattern over time, your family's history of asthma, eczema, hay fever and food allergy, the feeding and weaning history, and what happened when foods were removed or reintroduced. We examine your child, plot growth properly, and look for the other atopic conditions that travel with allergy.
Where skin prick testing will help, we arrange it. Testing is carried out by Melanie Davies, Allergy Nurse Specialist, at The Portland Hospital, where full resuscitation facilities are available. It is a second, separate appointment rather than part of the first. We can also arrange blood testing where that is the more useful investigation. Both are read against the history rather than on their own — which is precisely why the history comes first. A test is only as useful as the question you bring to it, and where testing would not change what happens next, we will say so rather than do it.
What a skin prick test can and cannot tell you
It can
Show whether your child has IgE antibodies to a specific allergen
Give a result in about 15 minutes, read on the day
Help confirm a diagnosis the history already points toward
Support a decision to reintroduce a food safely
It cannot
Tell you whether your child will actually react to that food
Detect delayed, non-IgE-mediated reactions
Make a diagnosis on its own
Predict how severe a future reaction would be
That last point is the one worth sitting with. A test result does not grade severity. A small wheal does not mean a mild allergy and a large one does not mean a dangerous one. Anyone who tells you otherwise is over-reading the test.
And before any test is done: a positive result shows sensitisation, not allergy. Children can test positive to foods they eat happily every day. A result read without the clinical history is one of the commonest routes into unnecessary food avoidance — and that is as true of a test we perform ourselves as of one done anywhere else. Offering testing and ordering it indiscriminately are not the same thing.
What the skin prick test is actually like
Testing is a separate appointment from your consultation. It takes place at The Portland Hospital with Melanie Davies, Allergy Nurse Specialist, where full resuscitation facilities are on hand. Parents ask what it actually involves more than anything else, so here it is in full.
Your child sits on your lap or on the couch with one forearm out. Melanie marks the skin with a pen — usually four to eight spots, sometimes more — and places a small drop of solution on each, plus two control drops so the result can be read against a known baseline. Each drop is then pricked through with a tiny plastic lancet. It is not an injection, no needle enters the skin, and it does not draw blood. Most children describe it as a scratch, and most of the ones who were dreading it say afterwards that it was fine.
Then there is a wait of about 15 minutes, which is the hard part if you are four. Bring a tablet or a book. Where a reaction occurs the spot becomes itchy and raised, like a nettle sting; each one is measured, and the itch settles within an hour or so.
The results are read on the day, so you do not go home waiting. We then interpret them against the history from your consultation and send you a written summary setting out what they mean — because, as above, a result on its own is not a diagnosis.
When we refer on
NICE sets out when a child should be referred to specialist allergy care, and we follow those criteria. We would consider referral if your child has:
faltering growth alongside gastrointestinal symptoms
not responded to a single-allergen elimination diet
had one or more acute systemic reactions
had one or more severe delayed reactions
confirmed IgE-mediated food allergy together with asthma
significant eczema where multiple or cross-reactive food allergies are suspected
We would also refer where concern persists despite a history that does not support allergy, where clinical suspicion of IgE-mediated allergy is strong but testing is negative, or where several allergies are suspected at once.
If that already describes your child, starting with us is still reasonable — we can make the referral and give the allergist a structured account to work from, which usually saves time at the other end.
What we commonly see
Suspected food reactions, hay fever and seasonal symptoms, eczema and allergic skin problems, and suspected reactions to medicines. We also see a good number of children whose symptoms turn out not to be allergic at all: reflux, viral rashes, food intolerance and ordinary infant feeding patterns are all mistaken for allergy, and sorting that out is a useful outcome in itself.
How an appointment works
Your consultation is at 77 Wimpole Street in Marylebone, The Cromwell Hospital in Kensington, or HCA Chiswick Outpatients. If skin prick testing is needed, that is arranged as a second appointment at The Portland Hospital. You do not need a GP referral.
Bring, if you have them: photographs of any reaction taken at the time, a note of what was eaten and when symptoms started, any previous test results, and a list of foods currently being avoided.
Afterwards you get a written summary setting out what we found, what we think is happening, what we have arranged, and what to do if things change. If a specialist referral is needed it goes out at the same time.
When to seek advice
Seek urgent same-day assessment through NHS services, or call 999 as above, for any reaction involving breathing, swelling of the mouth or throat, or collapse.
Otherwise it is worth arranging an assessment if your child has had a reaction you cannot explain, if foods are being avoided without a clear diagnosis, if eczema is proving hard to settle, or if you have been told to wait and see and the uncertainty is now shaping how your family eats.
Frequently asked questions
Does my child need an allergy test?
Not always. The history tells us more than a test does in most cases, and a test without a matching history can mislead. We arrange skin prick testing where it changes what happens next — and say so where it would not.
What does skin prick testing involve?
A drop of allergen solution is placed on the forearm and the skin pricked lightly through it with a small plastic lancet. It is not an injection and does not draw blood. Results are read after about 15 minutes. Testing is a separate appointment at The Portland Hospital with Melanie Davies, Allergy Nurse Specialist.
Can you diagnose allergy from a test alone?
No. Skin prick and blood tests both show whether your child has become sensitised to something, which is not the same as being allergic to it. Either result has to be read alongside the history.
What is the difference between an allergy and an intolerance?
An allergy involves the immune system and can cause immediate, sometimes serious reactions. An intolerance is a difficulty digesting something — uncomfortable, often dose-related, but not dangerous in the same way. They are managed quite differently, which is why distinguishing them matters.
Do I need a GP referral?
No, you can book directly. If your child is covered by private medical insurance your insurer may still require one for reimbursement, so check your policy first.
Will you be able to tell me what my child is allergic to?
Sometimes, clearly. Sometimes the honest answer after a first assessment is that it is not yet certain, and the right next step is specialist testing or a period of structured observation. We will tell you which of those you are in rather than guess.
Book an allergy assessment
Wimpole Street, Kensington or Chiswick. No GP referral needed.
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