All About Food Allergies – A Guide For Parents

General Medical

Tammy George

 Young boy with red hair eating orange slices

Discovering your child has a food allergy can be a worrying time for parents. Food allergies can range from mild to life threatening and there’s no way of knowing if the next contact will be worse than the last. In Australia and New Zealand around 10% of infants and 5-10% of children have a food allergy. Only 2% of the adult population suffer from a food allergy.

Food Allergy Vs Food Intolerance – What’s the Difference?

Many people use the term ‘food allergy’ when they have a food intolerance. Find out what separates the two: 

What is a Food Allergy?

A food allergy is when the body’s immune system overreacts to a food substance when eaten, inhaled or touched. The immune system overreacts by producing antibodies called immunoglobulin E (IgE).

The antibodies travel to cells that release chemicals, causing an allergic reaction. This can vary from sneezing and itching through to a life threatening anaphylaxis where the patient can stop breathing.

What is a Food Intolerance?

A food intolerance causes a range of symptoms that involve the digestive system including irritable bowel syndrome (IBS), stomach pain, gas, bloating and diarrhoea. Food intolerances don’t involve the immune system and therefore don’t usually cause severe, life threatening allergic reactions such as anaphylaxis.  

Common Food Allergies

Almost any food can cause an allergy but the following foods are the most common causes of allergic reactions in children. These nine foods cause 90% of food allergic reactions.

  • Peanuts

  • Tree nuts

  • Egg

  • Cow's milk

  • Soy

  • Wheat

  • Fish

  • Shellfish

  • Sesame

Food Allergy Reactions

A mild reaction to a food allergy may be redness on the skin, while a severe reaction is anaphylaxis where a person experiences trouble breathing. Unfortunately, food allergy reactions can be different every time a child comes into contact with the same food so it’s important to identify and treat allergies. An anaphylactic reaction is more likely to occur after eating peanuts, tree nuts, shellfish, milk and eggs.

Spread of foods that are common allergies.

Depending on the food allergy, the reaction can vary from person to person. There are four main areas of the body that are impacted by allergies:


The skin can show signs of a food allergy via small red bumps (hives), eczema, swelling, redness, itchy or swollen lips, mouth or tongue. 

Gastrointestinal Tract

A food allergy can cause stomach pains, vomiting or diarrhea. 

Respiratory System

A runny or stuffy nose, coughing, wheezing, sneezing and shortness of breath can be signs a child is allergic to the food. 

Young girl blowing her nose due to an allergic reaction.

Cardiovascular System

A food allergy can affect the cardiovascular system and cause a child to feel lightheaded or faint.

Natural Substances in Foods

Some naturally occurring substances are used to add flavour and change the smell of food but can trigger symptoms in some people. The most common substances that cause food intolerance reactions include: 

Monosodium Glutamate (MSG)

Monosodium glutamate (MSG) stimulates nerve endings and is used in some Chinese foods and processed snack foods. It can be found as additive number 621 or 625 in Australian packaged foods. Glutamates also occur naturally in foods including tomatoes, soy sauce, mushrooms, camembert and parmesan cheeses.


Amines are naturally occurring chemicals caused by bacteria that break down amino acids. Amines include tyramine, putrescine, spermine, spermidine, and cadaverine occur naturally in mango, red wine, pineapple, avocados, bananas, vegetables, nuts and some meats. They can cause small blood vessels to expand triggering migraines, flushing and nasal congestion in people who are intolerant.


A group of chemicals, salicylates are derived from salicylic acid that are found naturally in some herbs, fruits and spices. They’re also produced synthetically and used in aspirin, toothpaste and preservatives.


Lactose intolerance occurs when a person has insufficient lactase enzymes to digest the lactose in cows’ milk and other dairy products. It can cause bloating, gas, stomach upsets and diarrhoea after eating dairy foods.

Young girl drinking a glass of dairy milk.

How Food Allergies Are Diagnosed

Allergy testing may be recommended by a GP if a child is thought to be suffering from a food allergy with one or more of the following symptoms:

  • Anaphylaxis

  • Severe reaction to insect bites

  • Itchy skin, eczema

  • Itchy eyes, nose or throat

  • Runny nose or congestion

  • Vomiting, cramping or diarrhoea

Skin Testing

A skin prick test, also called a puncture or scratch test, checks for immediate allergic reactions on the skin to many different substances at once. It's performed by placing a tiny amount of allergens on the skin by pricking the surface.

Young boy getting a skin test for allergies

The test shows as positive if there’s swelling or itching around the pricked skin site. Reactions usually occur within 20 minutes and the small hive-like appearance will disappear within half an hour. A skin test may include a range of allergens including food, pollens, dust and pet dander.

Challenge Test

Most commonly used for testing foods and medicines, the challenge test involves eating a small amount of an allergen. The test is usually conducted by a doctor or allergist who can provide treatment if the child has a severe reaction.

Blood Test

A blood test isn’t commonly used but may be needed when a skin test can’t be performed due to a skin condition or medications being taken.

Conditions Linked to Food Allergies

Children who suffer from food allergies are often susceptible to other environment allergens. If the child has eczema or asthma or has a family history of either condition, they are more likely to suffer from a food allergy. However, a sibling with a food allergy makes a child only slightly more likely to develop one.

Sometimes a child may show symptoms that look like they’re allergic to a food but it may be that they suffer from another condition that caused the symptoms. A child may be lactose intolerant and has trouble digesting dairy products or can’t tolerate the protein gluten and the doctor diagnoses Celiac disease.

In some cases, a food allergy is suspected but the symptoms related to adverse reactions to food from food poisoning, toxic reactions, enzyme deficiencies, food aversion or irritation from skin contact.  

Treatments for Food Allergies

Unfortunately, there are few treatment options for food allergies. For mild symptoms, antihistamines can be given and for severe reactions, adrenaline.


Allergic reaction symptoms such as hives or a runny nose can be treated with antihistamines. They work by blocking the effects of histamines which your immune system has released from mast cells in your skin, lungs, nose, mouth, gut, and blood. Some antihistamines aren’t suitable for children under two years of age.


When a person suffers a severe allergic attack, they need adrenaline to narrow blood vessels to counteract low blood pressure and open the airways to assist with breathing difficulties.

Boy in class at school with Epipens on his desk.

The adrenaline is administered via an EpiPen (epinephrine auto-injector) and may be needed when a child suffers from shortness of breath, swelling, trouble breathing, or symptoms affecting two or more body parts. The EpiPen should be kept with the child at all times in case they suffer from anaphylaxis.


Some children are suitable for immunotherapy which involves exposing a food allergy sufferer to larger amounts of the allergen over time to try and change the immune system’s response. Immunotherapy can be successful in reducing the severity of reactions and the need for medication.

Immunotherapy for food allergies is new and isn’t yet part of clinical practice but has been used for insect bites, dust mite and grass pollen where the patient has severe symptoms and the cause is difficult to avoid.   


For many children, the best option is prevention. For their parents that means reading food labels to check if a product contains the allergen and if so, avoid giving it to their child.

Research into Food Allergies

Some of the advice around food allergies today contradicts the advice given 10 years ago. Research has improved our understanding of why allergies occur in some children and how to reduce the incidence but there is still a lot we don’t know.

Reasons for the Increase in Incidence of Food Allergy

Food allergies are 200 percent more prevalent today than they were 20 years ago. There has been no clear reason identified why the number of children are affected by food allergies compared to a generation ago but research is still ongoing.

The possible reasons for the increase in allergies being studied include:

Hygiene – less exposure to infections and bacteria in early childhood, the use of antibacterial soaps and sanitisers  

Diet – people are eating more processed foods today which impacts gut microbiome

Climate Change – crops are grown differently to account for temperature change that may provoke an immune system response

Environment – Exposure to chemicals, pollution and allergens

Food introduction - delayed introduction of highly allergic foods

Avoiding Foods that Cause Allergies

Recent studies have shown that delaying the introduction of some solid foods until after the age of 12 months can increase the chance of developing food allergies. It’s recommended that babies be introduced to solids between four and six months of age.

Women feeding a baby boy sitting in a highchair.

By their first birthday, all babies should have been introduced to common allergenic foods including peanut butter, cooked egg, dairy and wheat. If a baby is at high risk of an allergy, their first introduction to the food can be to rub a small amount on the inside of their lip and wait for 10 minutes to see if any allergic reaction occurs rather than giving the baby a larger portion to eat.

Pregnant and breastfeeding mothers are recommended to keep eating foods that most commonly cause allergies, unless they have an allergy.

Kids Outgrowing Their Food Allergy

Thankfully most kids grow out of food allergies, but not all will as it depends on what foods they’re allergic to. Around 80% of children will grow out of their allergy to milk, wheat and soy by the age of five. Roughly two thirds will outgrow an allergy to eggs. Other food allergies like nuts are harder to outgrow.


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Tips for Dealing with Food Allergies

Having a child with a food allergy takes time to adjust to the new normal. It’s important to take precautions but also continue to do the things you enjoy as a family.

  • Take potential food allergies seriously – speak to a GP even if the symptom is mild

  • Educate your child about only accepting food from their parents

  • Seek medical attention before conducting any dietary avoidance to prevent possible malnutrition and food aversion.  

  • Know the symptoms and be prepared with medication to treat them swiftly

  • Try to keep your fear and worry in check – don’t always focus on the worst-case scenarios

Tammy George

Please note: Tammy's blog is general advice only. For further information on this topic please consult your healthcare professional.

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