Originally published in 2023, fully updated and medically reviewed on January 19, 2026
Written and medically reviewed by Bahee Van de Bor, Registered Paediatric Dietitian.
Bahee has worked clinically at Great Ormond Street Hospital, is a former Chair of the British Dietetic Association Paediatric Group, and has contributed to national guidance on paediatric IBS and gut health.
If you are thinking about buying a food intolerance test for yourself or your child, you are not alone. With so many tests advertised online, it can feel tempting to try one, especially if your child struggles with tummy pain, diarrhoea, bloating, or unpredictable stools.
What many parents do not realise is that most food intolerance tests are not accurate.
Some are misleading and can send families down the wrong path, leading to unnecessary food restriction, ongoing symptoms, and a lot of frustration.
In this article, I explain what food intolerance actually is, explore the different types of food intolerance tests available, and help you understand whether they are worth your money.
By the end, you will know what works, what does not, and what to do instead.
Quick summary
- Accuracy: Most commercial food intolerance tests, including IgG blood tests and hair sample tests, are not scientifically reliable.
- The risk: These tests often lead to unnecessary food restriction and can increase the risk of nutritional deficiencies in children.
- What works: A dietitian-led elimination and reintroduction process remains the gold standard for identifying food-related triggers safely.
What is food intolerance?
Food intolerance describes difficulty digesting certain foods. It does not involve the immune system and is not life-threatening, but symptoms can be uncomfortable and disruptive.
In children, food intolerance can affect sleep, school attendance, appetite, mood, and bowel habits.
Medically, food intolerance is defined as an adverse reaction to food that does not involve an allergic immune response.
Food intolerance should not be confused with food allergy.
Common symptoms of food intolerance in children
Children with food intolerance may experience:
- Diarrhoea or porridge-like stools
- Bloating
- Tummy pain
- Excess wind
Some children may also experience:
- Rashes
- Headaches
- Fatigue
- Nausea
- Constipation
- Joint pain
Symptoms can vary widely, which is why testing can feel appealing. Unfortunately, most tests do not give reliable answers.
Common food intolerances in children
Lactose intolerance
Lactose intolerance is relatively common in both children and adults.
Lactose is a sugar found in milk and dairy products. Some people do not produce enough lactase, the enzyme needed to digest lactose properly.
Symptoms may include bloating, wind, tummy pain, and diarrhoea.
Lactose intolerance can be assessed using a hydrogen breath test, but in children it is often identified through a structured dietary trial under professional guidance.
Children with irritable bowel syndrome may also struggle with lactose due to gut sensitivity rather than a true enzyme deficiency.
Gluten, wheat and coeliac disease
If coeliac disease has been ruled out, many children who react to wheat are not reacting to gluten itself.
They may instead be sensitive to fructans, a type of fermentable carbohydrate found in wheat.
There is no reliable test for gluten intolerance.
The only validated test related to gluten is coeliac disease screening, which must be done while the child is eating enough gluten.
Therefore, removing gluten unnecessarily can complicate diagnosis and lead to overly restrictive diets.
FODMAP sensitivity and IBS
FODMAPs are a group of fermentable carbohydrates found in many everyday foods.
They are poorly absorbed in the small intestine and fermented in the large bowel. In sensitive children, this can trigger pain, bloating, wind, constipation, diarrhoea, or a mixture of both.
There is no IBS food intolerance test.
Symptoms are best assessed through a guided elimination and reintroduction process, tailored specifically for children and monitored by a registered dietitian.
Histamine intolerance
Histamine intolerance occurs when the body struggles to break down histamine found in foods such as aged cheese, cured meats, and fermented products.
Symptoms may include flushing, headaches, hives, itching, and gastrointestinal symptoms.
This condition is considered rare in children and should only be explored with medical guidance.
Sulphite sensitivity
Sulphites are preservatives used in some foods and drinks.
Symptoms may include headaches, wheezing, hives, tummy pain, dizziness, tingling sensations, or difficulty swallowing.
True sulphite sensitivity is uncommon but should be discussed with a healthcare professional if suspected.
Food allergy vs food intolerance
Food allergy and food intolerance are not the same thing.
Additionally, food allergy involves the immune system and can be serious, even life-threatening in rare cases.
Food intolerance is a digestive issue that causes discomfort but does not trigger an allergic immune response.
Food intolerance tests cannot diagnose food allergies.
Using them for this purpose can be dangerous and may delay appropriate medical care.
Understanding food allergy testing
IgE-mediated food allergy
IgE-mediated food allergies cause rapid reactions after eating a trigger food.
Diagnosis usually involves skin p
Non-IgE-mediated food allergy
Non-IgE-mediated allergies cause delayed symptoms, sometimes up to several days after eating a trigger food.
There are no validated laboratory tests for these reactions.
Diagnosis relies on careful history taking and a professionally guided elimination and reintroduction process.
Food intolerance tests are not recommended for diagnosing delayed food allergy.
What is a food intolerance test?
Food intolerance tests are commercially marketed tests that claim to identify food sensitivities or intolerances.
Most use blood, hair, or saliva samples.
In many cases, they label foods as problematic even when the child eats them regularly without issue.
This often leads to unnecessary food removal, ongoing symptoms, and nutritional risk.
Are food intolerance tests reliable?
Short answer: no.
There is no reliable food intolerance test for children or adults. National guidance from the NHS and professional dietetic bodies such as the British Dietetic Association does not recommend IgG food intolerance testing, as these tests are not supported by scientific evidence.
IgG blood tests explained
Many food intolerance tests measure IgG or IgG4 antibodies.
These antibodies actually indicate exposure to foods, not intolerance.
Why do IgG food intolerance tests often come back positive?
IgG antibodies are sometimes described as “memory antibodies”. They reflect foods a child has eaten, rather than foods that are causing symptoms.
If a child eats a food regularly, IgG levels to that food are more likely to be raised. This is a sign that the immune system recognises the food, not that the food is harmful.
This is why IgG food intolerance tests often flag multiple everyday foods, including foods a child tolerates well. Removing these foods rarely improves symptoms and can unnecessarily restrict the diet.
Hair sample food intolerance tests
Hair analysis tests claim to detect food intolerances using energy fields.
While hair testing can detect substances such as heavy metals, it cannot diagnose food intolerance.
There is no scientific evidence supporting its use for digestive symptoms.
Different types of Food intolerances tests
Food intolerance tests compared
| Test type | Reliability | Recommended for children? |
| IgG blood test | Very low | No |
| Hair analysis test | None | No |
| Hydrogen breath test (lactose) | High (when clinically indicated) | Occasionally |
| Elimination and reintroduction diet | Gold standard | Yes, with dietitian’s support |
How do you check if your child has a food intolerance?
In my clinical practice, I regularly see children whose diets have been reduced to just a handful of “safe” foods based on hair or IgG testing. Yet their symptoms persisted until we identified the true trigger through a properly guided elimination and reintroduction process.
The most accurate approach is a structured elimination and reintroduction diet, supervised by a paediatric dietitian.
This process allows you to:
- Identify true trigger foods
- Avoid unnecessary dietary restriction
- Protect growth and nutrition
- Improve symptoms sustainably
This approach is particularly effective for tummy pain, diarrhoea, constipation, IBS, and unpredictable stools.
Treatment for food intolerance
Treatment depends on the underlying cause.
Many children are placed on dairy-free or gluten-free diets unnecessarily and remain on them long term without proper nutritional support.
In clinical practice, many children improve without needing permanent food elimination.
Instead, we identify true triggers, restore gut function, and expand the diet wherever possible.
Can food intolerances go away?
Some intolerances, such as lactose intolerance, may worsen with age.
Others improve as the gut matures and the microbiome strengthens.
Supporting gut health, rather than excessive restriction, gives children the best chance of long-term improvement.
Frequently asked questions
Is there a food intolerance test for IBS?
No. There is no validated food intolerance test for IBS. Symptoms are best managed using a structured dietary approach, often involving FODMAP modification under professional guidance.
Can a hair test detect gluten intolerance?
No. Hair analysis tests cannot detect gluten intolerance or coeliac disease. The only reliable test related to gluten is coeliac disease screening, which must be carried out while eating gluten.
How long does an elimination diet take?
Most elimination phases last between 2 and 4 weeks, followed by a structured reintroduction. The exact timeline depends on symptoms and should be guided by a trained professional.
Bottomline
The bottom line
Online food intolerance tests are not reliable and are not recommended for children.
They often lead to unnecessary food restriction without resolving symptoms.
If you are concerned about food intolerance, the safest and most effective approach is working with your child’s GP and a paediatric dietitian.
Stop the guesswork
If you’re tired of restrictive diets, confusing test results, and ongoing tummy symptoms, you can book a free 15-minute assessment to discuss your child’s symptoms and the best next steps.
Bahee Van de Bor is a registered paediatric dietitian, specialising in gut health, food intolerance and fussy eating.
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