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Food Allergy Symptoms: Understanding Your Child's Symptoms

Food Allergy Symptoms: Understanding Your Child's Symptoms

If your child has an unpleasant physical reaction whenever they eat a certain type of food or foods, it can be very worrying. That’s because these reactions, when severe, can sometimes be life threatening.

Having an unpleasant and potentially harmful physical reaction to a food is called food hypersensitivity, with up to 10 per cent of children thought to be affected (i). There are two types of food-hypersensitivity reactions: food allergies and food intolerances.

Food allergy

According to Allergy UK, food allergy affects three to six per cent of children in the developed world, with estimates suggesting seven per cent of breast-fed children are affected in the UK (i). Severe allergies include peanut allergy, the incidence of which has doubled among children in Western countries during the past 10 years (i). Food allergies are also common in children with family members who have allergies.

Food allergy is caused by an adverse reaction to a food protein and involves the immune system. There are two types:

  • An IgE-mediated food allergy happens when your immune system overreacts to a food protein and produces immunoglobulin E (IgE) antibodies. These antibodies travel to cells that release chemicals, which triggers an allergic reaction. IgE antibodies can be produced in response to non-food allergens too.

    With an IgE-mediated allergy, symptoms typically start immediately or within minutes of being exposed to the food in question, and can be severe enough to be life threatening (anaphylaxis). An estimated 0.25 - 0.95 per cent of children in the UK experience peanut and tree nut anaphylaxis (i). 

  • The other type of food allergy is a non-IgE-mediated food allergy. This is caused by a reaction that involves other parts of the immune system besides IgE antibodies – exactly how this type of allergy works is far less understood than IgE-mediated allergy.

    With a non-IgE-mediated food allergy symptoms don’t usually start quickly, but can develop between two hours and two days after exposure to the food. Non-IgE-mediated food allergies are, however, very rarely life threatening because they don’t cause anaphylaxis.

The most common foods that cause allergic reactions in children include:

  • Cow’s milk

  • Hen’s eggs

  • Shellfish (especially prawns)

  • Fish

  • Soya

  • Peanuts

  • Wheat

  • Tree nuts (eg hazelnuts, almonds, walnuts, cashews, pistachios and Brazil nuts)

Food allergy can sometimes develop in children who have other allergies. According to the British Society for Allergy & Clinical Immunology (BSACI), children who have eczema early on in their lives have a high risk of developing food allergy – particularly peanut allergy – with almost one in five developing an allergy to peanuts by the time they reach their fifth birthday. Young children with moderately severe or severe eczema also have a 30 - 50 per cent risk of being food allergic (ii).

Food intolerance

This is also an adverse reaction to a food, this time caused by a mechanism that doesn’t involve the immune system. According to the National Institute of Health and Care Excellence (NICE), food intolerance can be caused by enzyme deficiencies, pharmacological agents and naturally occurring substances (iii).

Lactose intolerance is a common example of an enzymatic food intolerance. It’s found in those who have either too little or no lactase, an enzyme that helps digest the milk sugar lactose. Pharmacological intolerances, on the other hand, involve reactions to natural substances in foods including histamine and salicylates (substances similar to aspirin).

Meanwhile, children with a food intolerance may experience symptoms straight after eating a food, or their symptoms – which can range in severity – may happen later. The good news is food intolerances are rarely life threatening.

Foods and substances in foods that can cause an intolerance reaction include:

  • Dairy foods (as they contain lactose)

  • Wheat (this may be an intolerance to gluten – a protein in wheat – or another substance found in wheat)

  • Monosodium glutamate (MSG)

  • Caffeine

  • Artificial sweeteners

  • Histamine (this is found in mushrooms, pickled foods, cured foods and Quorn)

  • Foods contaminated with toxins, viruses, bacteria or parasites

  • Some artificial food colours, preservatives or flavour enhancers


Food allergy symptoms

There is a range of symptoms – immediate and delayed – that can be caused by food allergy, affecting the skin, the gastrointestinal system and respiratory systems.

Skin symptoms:

Immediate symptoms (IgE-mediated) include:

  • Itching

  • Redness/flushing

  • Acute urticaria (a raised, itchy rash, also known as hives or nettle rash)

  • Swelling under the skin (acute angioedema), most often affecting the lips and face, and the area around the eyes

Delayed symptoms (non-IgE-mediated) include:

  • Itching

  • Redness

  •  Atopic eczema (areas of skin that are itchy, dry, cracked, sore and red)


Gastrointestinal symptoms:

Immediate symptoms (IgE-mediated) include:

  • Swelling (angioedema) of the lips, tongue and palate

  • Itching in the mouth

  • Nausea

  • Abdominal pain

  • Vomiting

  • Diarrhoea - To find out remedies, read our article here

Delayed symptoms (non-IgE-mediated) include:

  • Loose or frequent stools

  • Blood and/or mucus in stools

  • Abdominal pain or colic

  • Refusing food

  • Constipation

  • Redness around the anal area

  • Pale skin and tiredness

  • Low weight or low weight gain


Respiratory symptoms

These usually happen immediately and alongside one or more skin or gastro-intestinal symptoms:

  • Nasal itching, sneezing or congestion

  • Chest tightness, wheezing, coughing or shortness of breath

If your child has any immediate symptoms after eating your GP can refer them for blood tests or skin prick tests to check for the presence of IgE antibodies.

There aren’t however any validated tests that can diagnose non-IgE-mediated food allergy. But if this is suspected you may be advised to do a food avoidance test, where certain foods are removed from your child’s diet for about four weeks, then reintroduced to see if a reaction happens.

Please note: it’s never advisable to do a food avoidance test involving a child without help from a specialist or dietitian, as there’s a risk it could cause nutritional deficiencies.

How to recognise anaphylaxis

Severe symptoms (anaphylaxis) that require urgent medical attention include chest tightness or wheezing (like an asthma attack) and swelling of the tongue and throat (as this can restrict a child’s airways). Anaphylaxis can also cause a sudden drop in blood pressure, causing shock, as well as dizziness, confusion, collapse, loss of consciousness and sometimes coma. If your child is experiencing severe symptoms, call 999 for an ambulance immediately.

If your child is diagnosed with a severe food allergy their GP may recommend that you take every precaution to make sure they don’t come into contact with the food in question, which means taking care when buying food or eating out. Your child may also be given adrenaline medication in the form of an auto-injector that will help protect them if they are or may be experiencing anaphylaxis.

How to spot a food intolerance

According to the NHS it’s hard to know how many people – including children – are affected by food intolerance, as many assume they have a food intolerance when their symptoms might be caused by something else (iv) (according to the BSACI about 20 per cent of the population alter their diet because they believe they have a food intolerance (v) ).  

In general, however, the symptoms – which are usually less severe than food allergy symptoms – include:

  • Stomach pain

  • Bloating

  • Wind

  • Diarrhoea

  • Skin rashes and itching

Tests are available for food intolerances but you can’t get them on the NHS, which points out that they aren’t based on scientific evidence. You can, however, try to find out if your child is affected by a food intolerance by keeping a diary of everything they eat and any symptoms that happen, including when the symptoms begin.

This record can help your GP decide if you should try putting your child on a food avoidance test with the help of a registered dietitian.

Preventing food allergy

If your child is diagnosed with a food allergy or food intolerance the only treatment is to avoid the food that’s causing the problem. However, it’s important to make sure their diet is still nutritionally balanced if any type of food or foods are cut from it.

Some children, on the other hand, will grow out of a food allergy, especially if they developed the allergy when they were very young – though some allergies, such as a peanut allergy, rarely goes away.

But is there anything you can do to stop a food allergy developing in your child? According to the BDA (the Association of UK Dietitians) and the BSACI, UK health departments currently advise the following for healthy babies (vi) :

  • They should be breastfed exclusively for around the first six months of their life.

  • Start introducing solid foods when your baby is around six months old (but not younger than four months), including foods that are part of your family’s normal diet that are commonly associated with food allergies, alongside continued breastfeeding. At first, start them on pureed foods, including small amounts of vegetables, fruit, starchy foods, protein and pasteurised dairy – never add salt of sugar.

  • Do not exclude eggs and peanuts from your baby’s diet, as this may increase their risk of developing a food allergy. Aim to have introduced eggs and peanuts to their diet by the time they are a year old, and continue to feed these to your baby as part of their usual diet. If, however, your baby has severe eczema, speak to your healthcare professional before introducing eggs and peanuts into their diet.

  • Never give whole nuts, coarsely chopped nuts or chunks of peanut butter to children under the age of five, as they can cause choking.


Introducing allergenic foods

There are a few things you can do when you start giving your baby foods that are known to cause food allergies, including:

  • Start with a very small amount – a quarter or half a teaspoon, for example – then increase the amount slowly over the next few days.

  • Don’t start giving your baby two new foods on the same day, introduce each new food one at a time.

  • Once your baby is used to eating a new food, continue giving it to them regularly as part of their normal diet (at least once a week).

  • If your baby refuses to eat a new food, just try again on another day.

  • Be on the look-out for any signs of a food allergy or intolerance – if you spot any reaction, stop giving them the food that’s causing it and see your GP for advice. This can be easier if you start giving them new foods on days when they are well.

  • If you think your baby may be allergic or intolerant to cow’s milk, always speak to a healthcare professional before using any alternatives, including infant formula alternatives, as some may not be suitable.

Natural support for allergy and intolerance

There aren’t any nutritional supplements that treat food allergy and intolerance in children or adults. However, certain supplements may help, including those that support your child’s immune system, such as the following:

Multivitamin and mineral

A multivitamin and mineral supplement can help make sure your child is getting all the major nutrients their growing body needs. Look for a supplement that includes the right level of vitamin D, as this helps support normal immune function. Indeed, a daily vitamin D supplement is recommended for all children by the government organisation Public Health England (vii). PHE experts say that if your child is aged one to four years old they should have a daily 10mcg vitamin D supplement, with babies under a year old needing a daily 8.5 - 10mcg vitamin D supplement (though if they have more than 500ml of infant formula a day, they don’t need any additional vitamin D).

Look for a supplement that’s formulated for children, including sugar-free chewable products or tablets that dissolve in water to make a fizzy drink.

Vitamin C

A good-quality multivitamin and mineral will also give your child vitamin C and zinc, both of which also help support immune function (viii). You can also make sure your child is getting plenty of vitamin C by including foods in their diet including oranges, strawberries, kiwi fruit, tomatoes, peppers and broccoli. Good sources of zinc include dairy foods, bread and cereal products.

Live bacteria

If your child is having digestive symptoms, a live bacteria supplement may be useful. Look for products that contain live bacteria such as Lactobacillus acidophilus and Bifidobacterium. Meanwhile natural soluble fibre supplements – such as those that contain an active ingredient called fructo-oligosaccharides (FOS) – can also help boost children’s digestive systems by helping to maintain normal intestinal health (note: these are usually suitable for children aged four years and older).


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  8. , , Essential role of vitamin C and zinc in child immunity and health. J Int Med Res. 38(2):386-414. Available online:


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Disclaimer: The information presented by Nature's Best is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. Self-treatment is not recommended for life-threatening conditions that require medical treatment under a doctor's care. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications.

Our Author - Christine Morgan


Christine Morgan has been a freelance health and wellbeing journalist for almost 20 years, having written for numerous publications including the Daily Mirror, S Magazine, Top Sante, Healthy, Woman & Home, Zest, Allergy, Healthy Times and Pregnancy & Birth; she has also edited several titles such as Women’ Health, Shine’s Real Health & Beauty and All About Health.

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