About food allergies
If you have a food allergy, your immune system reacts to a particular food as though the food is toxic. This food is called an allergen. Your immune system tries to protect your body against the allergen by releasing chemicals like histamines into your body’s tissues.
Even tiny amounts of the food you’re allergic to can cause an allergic reaction. This reaction can be immediate or happen hours or even days later.
Around one in 20 children have food allergies. Most reactions aren’t severe and deaths are extremely rare.
Immediate-onset food allergies: symptoms
The symptoms of immediate-onset food allergies usually appear within a few minutes. But sometimes symptoms can appear up to two hours after a child has eaten the food.
Mild to moderate symptoms of immediate-onset food allergies include:
- swollen lips, face or eyes
- skin reactions like redness, hives or eczema
- tingling or itchy mouth
- vomiting, stomach pain or diarrhoea
- nasal congestion.
A severe allergic reaction is called anaphylaxis, and it can also happen immediately. Its symptoms include:
- breathing difficulties or noisy breathing
- tongue and throat swelling or tightness
- a wheeze or persistent cough
- difficulty talking or a hoarse voice
- persistent dizziness or fainting
- paleness and floppiness (in young children)
- low blood pressure.
Delayed-onset food allergies: symptoms
The symptoms of delayed-onset food allergies appear more than 2-4 hours after a child comes into contact with the food and sometimes many days later.
Symptoms of delayed-onset food allergies include vomiting, diarrhoea, bloating and stomach cramps. This usually isn’t life threatening.
Common food allergies
The most common food allergies are to nine main foods:
- cow’s milk
- hen’s eggs
- tree nuts like cashews, pistachios, walnuts, pecans or hazelnuts
Diagnosing food allergies in children
Immediate-onset food allergies
Tests for immediate-onset allergies include the following:
- Skin-prick test: your child’s skin is pricked with a small device that looks a bit like a toothpick and that contains a drop of a specific allergen. If your child is allergic, a red lump might come up where the skin has been pricked.
- Blood tests: the serum specific IgE antibody test uses your child’s blood to see whether she’s sensitive to specific allergens. Your child might have this test if she can’t have skin-prick testing because she has severe eczema or has taken an antihistamine in the five days before the test.
- 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 should be conducted only by medical specialists in a setting where anaphylaxis can be safely and quickly treated.
Delayed-onset food allergies
If your child has a delayed-onset food allergy, diagnosis usually happens through an ‘elimination and rechallenge’ 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 reintroduce only one food at a time so it’s easier to identify the food that’s causing the allergy.
Managing food allergies in children
There’s currently no cure for food allergies, 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 any foods or cutlery that could have been in contact with the food she’s allergic to.
You can do two important things to help your child avoid the food:
- Read labels on all foods. 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 – these are the nine foods listed above, plus 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.
Have an action plan
You should 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 auto-injector
If your child is at risk of anaphylaxis, he might be prescribed an adrenaline auto-injector like EpiPen®. These auto-injectors make it easy to self-inject adrenaline. Your doctor will teach you and your child (if old enough) how and when to use it.
It’s important that key people – like family, carers, babysitters and your child’s school – know how and when to use your child’s adrenaline auto-injector.
Consider a medical bracelet
Your child might wear a medical bracelet that lets people know she has an allergy.
How long do food allergies last?
Most children grow out of their food allergies by adolescence, especially children who are allergic to milk, egg, soybean or wheat.
Allergies to peanuts, tree nuts, fish and shellfish are more likely to be lifelong. Allergy to gluten, known as coeliac disease, is also lifelong.
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 other allergy problems like food allergy, 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.
How to reduce your child’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 every day 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 he’s ready to start eating solid foods at around six months old. It’s best to keep breastfeeding until your baby is at least 12 months old.
Introduce solids from around six months of age
You should start to introduce solid foods to your baby from around the age of six months, but not before four months. Introducing solids before four months or after six months is associated with an increased risk of food allergy.
You can introduce new foods gradually (every 2-3 days). You don’t need to avoid any particular allergenic foods.