What is a food allergy?

A food allergy is when the body's immune system reacts to a food as if it was toxic by causing symptomsMost of the time, an allergic reaction might cause mild to moderate symptoms (rash or a sore tummy), but in rare cases, it can cause a severe reaction called anaphylaxis. If a child reacts to a certain food the same way every time it’s eaten, they likely have an allergy to that food. 

The most common food allergies are to:  

  • cow’s milk 
  • eggs 
  • peanuts 
  • tree nuts like almonds and cashews 
  • soy  
  • fish 
  • shellfish  
  • wheat 
  • sesame seeds 

In New Zealand, these ingredients have to be listed on food labels, even if the product only contains very small amounts of them. 

Allergies often run in families, so a baby with whānau who have allergies are at a higher risk of developing food allergies. Babies with no family history can still develop food allergies. 

Babies with eczema also have a higher chance of developing a food allergy. 

Most children grow out of their allergies, but for some this can take years. Symptoms can be mild to severe, can start rapidly, or be gradual or delayed. 

How can I tell if my child has a food allergy?

Symptoms of a reaction to food normally develop right after or within hours of eating. 

Signs of a mild or moderate food allergy are: 

  • runny nose, sneezing, asthma, coughing or wheezing 
  • skin problems (itching and rashes) 
  • stomach cramps, diarrhoea, nausea, vomiting or colic-like symptoms. 

Signs of a serious food allergy are: 

  • swelling lips, mouth, tongue, face, and/or throat (act immediately and call 111)
  • dizziness, difficulty breathing, and/or collapse (act immediately and call 111)
  • pale and floppy (in young children).

How are food allergies diagnosed?

If you think your baby has a food allergy, go to your GP for advice. If symptoms appear within a few minutes every time your child eats a particular food, it makes it easy to identify which food is causing the reaction. But if the cause isn’t known, your child might need to see an allergy specialist for a skin prick or a blood test to identify which foods are causing the reaction. 

How do you treat food allergies?

There’s no cure for food allergies, but they can be managed 

  • If your baby’s diagnosed with a food allergy, don’t feed them that food.  
  • Remember some processed foods may contain traces of allergens.  
  • Anaphylactic reactions are treated with adrenaline, using an auto-injector like an EpiPen. 
  • Under management by an allergy specialist, some foods, like egg and milk, can be introduced gradually in baked products until they can be safely eaten raw. This is thought to help speed up the growing out of an allergy. 
  • Some allergy specialists use immunotherapy as a treatment for food allergy. This involves giving tiny amounts of that food protein to the patient, then slowly increasing that amount to desensitise the immune system to that food.  

Preventing allergies in babies

Delaying the introduction of the common allergy causing foods doesn’t prevent food allergy. Research shows that if you give your baby these foods before they turn one, it can greatly reduce the risk of them developing a food allergy.  

Even if you have a family history of food allergy or not, include common allergy-causing foods when you introduce other first solid foods, at around six months old. Add a new food every two to four days to give you time to notice any reaction.

Food allergies

Allergy New Zealand

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Information, education, and support for New Zealanders living with allergies.