About food allergies
If you have a food allergy, your immune system reacts to a particular food when the food enters your body. This food is called an allergen.
Your immune system reacts by releasing histamine and other substances into your body’s tissues. This leads to the symptoms of an allergic reaction.
Even tiny amounts of the food you’re allergic to can cause an allergic reaction. Some reactions can happen immediately, and others can happen several hours later.
Allergic reactions are common. But most reactions aren’t severe, and deaths are extremely rare.
Food allergies aren’t the same as food intolerances. A food intolerance is a reaction to the food you’re eating, but the reaction isn’t caused by your immune system. Food allergies are generally more severe and have more symptoms than food intolerances.
Immediate-onset food allergies: symptoms
The symptoms of immediate-onset food allergies usually appear within a few minutes. But sometimes symptoms can appear 1-2 hours after a child has eaten the food.
Mild to moderate symptoms of immediate-onset food allergies include:
- swollen lips, face or eyes
- changes in skin colour – red on lighter skin, and brown, purple or grey on darker skin
- tingling or itchy mouth
- stomach pain, vomiting or diarrhoea
- sneezing or a blocked nose.
A severe allergic reaction is called anaphylaxis, and it can also happen immediately. Signs and symptoms of anaphylaxis include:
- difficult or noisy breathing
- tongue swelling
- throat swelling or tightness
- difficulty talking or a hoarse voice
- a wheeze or persistent cough
- persistent dizziness or fainting
- paleness and floppiness (in young children)
- severe stomach pain, vomiting or diarrhoea.
Anaphylaxis is a life-threatening allergic reaction and needs urgent medical attention. If your child is having an anaphylactic reaction, first lay your child flat or keep them sitting. Don’t let your child stand or walk around. Next use an adrenaline injector like EpiPen or Anapen if one is available. Then call an ambulance – phone 000.
Delayed-onset food allergies: symptoms
The symptoms of delayed-onset food allergies appear more than 2-4 hours after a child has eaten the food. Sometimes symptoms appear many hours later.
Symptoms of delayed-onset food allergies include vomiting, diarrhoea, bloating and stomach cramps. Occasionally there might be mucus or blood in the poo.
Delayed-onset allergies aren’t usually life threatening.
Common food allergies
The most common food allergies are to:
- cow’s milk
- tree nuts like cashews, pistachios, walnuts, pecans or hazelnuts
Assessment and diagnosis of food allergies in children
Immediate-onset food allergies
Tests for immediate-onset food allergies include the following:
- Skin-prick test: your child’s skin is pricked with a special device that looks a bit like a toothpick and contains a drop of a specific allergen. If a hive comes up where your child’s skin has been pricked, your child might have an allergy.
- Blood tests: the IgE antibody test checks whether your child has a high level of IgE antibodies to a specific allergen. A high level means your child is likely to have an allergy. Your child might have this test if they can’t have skin-prick testing.
- Oral food challenge: sometimes your child will be given the possible allergen in a safe, supervised setting. Medical and nursing staff will watch to see whether an allergic reaction happens. This test carries a risk of anaphylaxis so only allergy and immunology specialists should conduct it in a place where anaphylaxis can be safely and quickly treated.
Only your GP, allergy and immunology specialist or paediatrician can order and assess allergy tests.
Delayed-onset food allergies
If your child has a delayed-onset food allergy, diagnosis usually happens through an ‘elimination and re-challenge’ test.
This involves removing possible allergy-causing foods from your child’s diet, then reintroducing them when your child’s allergy specialist thinks it’s safe to do so. You remove and reintroduce only one food at a time so it’s easier to identify the food that’s causing the issue.
Your allergy and immunology specialist or dietitian will guide this test.
You might hear about IgG food antibody testing, Vega testing, Cytotoxic testing, Alcat testing, pulse testing, iridology, kinesiology, VoiceBio analysis and stool or hair analyses. These aren’t scientifically proven as allergy tests. Tests that are backed up by science are most likely to work, be safe for your child, and be worth your time, money and energy.
Managing food allergies in children
There’s no cure for food allergies yet, but many children grow out of them. You can also take some steps to make it easier for you and your child to live with food allergies.
Avoid the food
It’s important for your child to avoid the food. This can be challenging, particularly as eating even tiny amounts can cause an allergic reaction. Your child also needs to avoid foods and cutlery that could have been in contact with the food they’re allergic to.
You can do 2 important things to help your child avoid the food:
- Read and make sure you understand all food labels. Be aware that some allergenic foods have different names – for example, cow’s milk protein might be called ‘whey’ or ‘casein’. But by law 10 allergens must be plainly stated on food labels – cow’s milk, soy, egg, wheat, peanut, tree nuts, sesame, fish, shellfish and lupin.
- Be careful when you eat out. Ask what ingredients each dish includes, how it was prepared, whether it has touched any other foods, and whether there’s any risk of cross-contamination. Most restaurants are happy to tell you, but they might not know about the ingredients in some foods like sauces. It’s best to avoid buffets and bain-maries (food warmers) because it’s very possible that ingredients have been transferred from one dish to another.
Have an action plan
Talk to your doctor about an ASCIA (Australasian Society of Clinical Immunology and Allergy) action plan. This will help you recognise and treat symptoms if your child eats something that causes an allergic reaction.
Know how to use an adrenaline injector
If your child is at risk of anaphylaxis, your doctor might prescribe an adrenaline injector like EpiPen or Anapen. These injectors make it easy to self-inject adrenaline. Your doctor will teach you and your child, if they’re old enough, how and when to use it.
Let people know about the allergy and its management
It’s important that family, carers, babysitters, early childhood educators and teachers know that your child has a severe allergy. It’s a good idea for them also to know how and when to use your child’s EpiPen or Anapen. They should also have a copy of your child’s anaphylaxis action plan.
Wear a medical bracelet
This lets people know about your child’s particular allergy. This can be important if your child has an allergic reaction and there are no people around who know about their allergy.
How long do food allergies last?
Most children grow out of food allergies by the time they’re in primary or secondary school, especially children who are allergic to cow’s milk, egg, soybean or wheat.
Allergies to peanuts, tree nuts, fish and shellfish are more likely to be lifelong.
If you think your child might have grown out of an allergy, see your GP or allergy and immunology specialist for an assessment. Don’t experiment at home to see whether your child has outgrown the allergy. Your doctor will let you know whether it’s safe for you to introduce the food at home or whether this should happen under medical supervision.
How to reduce children’s risk of food allergies
You can take some simple steps that might help reduce your child’s risk of developing food allergies.
Eat a well-balanced and nutritious diet while pregnant or breastfeeding
When you’re pregnant or breastfeeding, it’s important to eat a wide variety of healthy foods including fruit, vegies, grains, protein and dairy or calcium-enriched products.
Avoiding foods that commonly cause allergies – for example, eggs and peanuts – while you’re pregnant or breastfeeding won’t reduce the risk of your baby developing allergies. In fact, avoiding too many foods can be dangerous, because your baby won’t get important nutrients.
Breastmilk is best, so it’s recommended that you exclusively breastfeed your baby until it’s time to introduce solid foods at around 6 months old. It’s best to keep breastfeeding until your baby is at least 12 months old, if you can.
Talk to a doctor or nurse about infant formula
For parents bottle-feeding with infant formula, there’s no evidence that giving babies hydrolysed infant formula or partially hydrolysed infant formula (which is also called hypoallergenic or HA formula) instead of standard cow’s milk formula prevents allergies. But some evidence suggests that these formulas might help to manage cow’s milk allergy.
If you’re not sure what formula is best for your baby, talk to your child and family health nurse, GP or paediatrician.
Introduce allergenic solids from around 6 months of age
Introducing allergenic solid foods early can reduce the risk of your child developing a food allergy. All babies, including babies with a high allergy risk, should have solid foods that cause allergies from around 6 months of age.
These foods include well-cooked egg, wheat (from wheat-based breads, cereals and pasta), peanut butter, tree nut paste (like cashew or almond paste), soy products (like tofu), sesame, shellfish and other seafood.
Your baby doesn’t need to avoid any particular allergenic foods.
Allergy risk facts and factors for children
Most children with food allergy don’t have parents with food allergy. But if a child’s parents have a food allergy or other allergy problems like asthma, eczema or hay fever, the child has an increased risk of food allergies.
Babies with severe eczema in the first few months of life are at an increased risk of developing food allergy.