Allergy or intolerance in children – How to spot the difference


Allergies and intolerances —the two terms are often used interchangeably, which can be quite confusing for parents. What's the difference between the two, and why does it matter?

Allergies and intolerances may seem similar, but they're quite different. It's a good idea to know which is which, and the information below will help explain the main differences between food allergies and intolerances. 

MEDICAL DISCLAIMER: The information included in this material is for informational purposes only. Always seek medical advice for any concerns about health and nutrition.

What is food allergy?

Food allergy is an adverse immune response to a specific protein within certain foods and represents a relatively rare but potentially significant health concern. Individuals with a familial history of allergies face an elevated risk of developing food allergies, suggesting a genetic predisposition. 

This means allergies to specific foods lie in their capacity to trigger reactions, even when exposed to minimal amounts of the allergenic substance. That is why it's really important for parents with a child who has a food allergy to be extra cautious, carefully check food labels, and stay well-informed about potential risks.

Causes and Symptoms of food allergy

Any food containing protein has the potential to trigger an allergy; however, there are some more common culprits than others, including peanuts, tree nuts, fish and shellfish, cow’s milk, eggs, soya, and wheat.

The immune system thinks the protein in the food is harmful and reacts to it, causing symptoms such as;

  • Redness
  • Swelling
  • Difficulty breathing
  • Skin reactions (itching, hives, anaphylaxis, among others)

What is food intolerance?

On the other hand, food intolerance is an adverse bodily response to a component within a food (not necessarily a protein) with no immune involvement. It is also rare, but the risk is higher in families with a history of allergies. Usually, a reaction only happens after consuming at least a teaspoon of the food. More common than an allergy, but still unusual in children. 

Causes and Symptoms of food intolerance 

Dairy is the most common source. People with intolerance for dairy produce less of the enzyme the body needs to break down the food, which may lead to uncomfortable symptoms. There are several causes; sometimes a lack of enzymes means food can’t get digested, or sometimes foods can cause symptoms on their own. Symptoms include;

  • Headache
  • Bloating
  • Stomachache
  • Diarrhea
  • Sickness
  • No anaphylaxis

How to know, whether your child has an allergy or intolerance?

Food allergies often result in immediate and potentially severe reactions, such as hives, itching, swelling, or respiratory problems, shortly after exposure to the allergen. For some, mild symptoms can be controlled with antihistamines. 

If the food allergy is severe, you may need to keep adrenaline (an EpiPen) on hand. If the food is a major part of the diet, nutritional advice may be needed. Reintroduction of food may be performed under medical supervision to see if the allergy persists into adulthood.

In contrast, food intolerances typically lead to milder and delayed symptoms, often centered around gastrointestinal discomfort, like bloating, gas, diarrhea, or stomach cramps, hours or even days after consuming the problematic food. Mild symptoms can be controlled with antihistamines. 

You may also keep adrenaline (an EpiPen) on hand if the allergy is severe. Adrenaline is not required. As some children can ‘grow out of’ food intolerances, reintroduction of food may be performed under medical supervision. If the food is a major part of the diet, nutritional advice may be needed. 

How does pediatric allergy testing work?

Pediatric allergy testing typically involves different methods: skin prick tests, blood tests and many more. These diagnostic tests help identify allergens that may be triggering allergic reactions in children, aiding in diagnosis and treatment planning.

Here are some ways to find out if your child has a food allergy or intolerance —plus a few practical tips. Here are the diagnostic tests that your doctor may request:

  • Skin prick test (SPT)- During this test, an allergist will place drops of solutions containing different potential allergens on the skin, then use a tiny lancet to prick through the solution and into the top layers of the skin. A few minutes later, the allergist will check to see whether the skin has reacted by swelling or turning red; this shows a specific type of allergy called an ‘IgE allergy’.

  • Blood tests (RAST or ‘specific IgE’ test)- This involves taking a blood sample and counting the number of ‘IgE’ antibodies it produces in response to the suspect food.

  • Challenge Test- In this test, the allergist will place very small amounts of the suspect food in your child’s mouth and observe any symptoms (under medical supervision).

  • Food exclusion and reintroduction- This 'test' involves removing the suspect food from your child’s diet to see what effect this has on symptoms. If the symptoms improve, then your doctor may suggest re-introducing the food briefly to see if the symptoms return.  

Essentially, your decision about allergy testing is entirely up to you; however, consulting your doctor ensures you that you will only be treated by trained medical professionals, using techniques that have been thoroughly studied and have good quality evidence to show that they work. 

Frequently asked questions on allergies and intolerances:

What should I do if I think my child has a food allergy or food intolerance?

If you suspect that your child may have an abnormal reaction to a food, it's important to discuss it with your doctor right away. Sometimes what looks like an allergy or an intolerance might be something different, so you don’t want to take things out of your child’s diet until you're certain of the cause.

What sorts of foods are likely to trigger an allergy or intolerance?

Any food containing protein has the potential to trigger an allergy; however, there are some more common triggers than others, including peanuts, tree nuts, fish and shellfish, cow’s milk, eggs, soya, and wheat.

How is food allergy testing done?

Food allergy testing includes various methods, such as the Skin prick test (SPT), where potential allergens are applied to the skin and reactions are assessed for 'IgE allergies.' Blood tests (RAST or ‘specific IgE’ test), analyze blood samples for IgE antibodies in response to suspected allergens. Food challenge tests and Food exclusion/reintroduction further contribute to identifying food allergies or intolerances in children under medical supervision.

How to test for food intolerance?

Food intolerance can be tested through elimination diets, where suspected trigger foods are temporarily removed and then reintroduced to observe reactions. Keeping a “food diary” helps track symptoms and identify patterns of intolerance. It also includes blood testing, and may also be used to measure immune responses to specific foods, but their efficacy is a subject of debate within the medical community.


[1] Better Health Channel (2012). Food allergy and intolerance. [online] Better Health Channel. Available at:

[2] Hirsch, L. (2015). What’s the Difference Between a Food Allergy and a Food Intolerance? (for Parents) - Nemours KidsHealth. [online] Available at:

[3] Cleveland Clinic (2017). Allergy or Intolerance: How Can You Tell the Difference? [online] Health Essentials from Cleveland Clinic. Available at:

[4] (n.d.). Diagnostic Tests for Allergy in Children. [online] Available at:

[5] Healthline. (2019). Allergy Testing for Children: What Age and What to Expect. [online] Available at:  [Accessed 15 Nov. 2023]

[6] (2018). Anaphylaxis: MedlinePlus Medical Encyclopedia. [online] Available at:

[7] Li, J. (2019). Food allergy vs. food intolerance: What’s the difference? [online] Mayo Clinic. Available at:


If you wish to receive priority alert on related articles, you may provide us your information: 

click here 

Chat with us on Messenger at