Food allergies

Food allergy and food intolerance are commonly confused as the symptoms can be similar. A food intolerance is an unpleasant reaction to a food, but it doesn't involve your immune system. 

Food intolerances can have various causes. Symptoms, such as bloating, headaches and tummy pain, may happen within hours to days after a food is eaten. A food intolerance is not life-threatening and doesn't include immediate, severe reactions such as anaphylaxis.

There are lots of expensive intolerance tests available (eg, hair test) but none of these are valid and should be avoided. Read more about the difference between food allergy and intolerance.

A food allergy can develop at any age, but it's most common in tamariki under 5 years of age. About 1 in 10 infants have a food allergy by 12 months of age. Read more about reducing food allergies in infants.

Some people will grow out of their food allergies (mainly allergies to milk or eggs) – it's estimated that 6–8% of school age children and 2–4% of adults have a food allergy. 

You have a slightly higher chance of getting a food allergy if you or a close family member have any allergies, asthma or eczema.

Developing a food allergy as an adult isn't common. Food intolerance is much more common in adults and can have a variety of causes. Read more about the difference between food allergy and intolerance.

Do food allergies last for life?

Most children who are allergic to cow's milk, soy, wheat or egg will ‘outgrow’ their food allergy. About 80% of children eventually tolerate these foods by 5 years of age.

However, peanut, tree nut, seed and seafood allergies tend to be lifelong allergies.

Although almost any food can cause an allergic reaction, the main foods causing food allergy in Aotearoa New Zealand are:

• dairy (cow's milk)
• eggs
• fish
• peanuts
• sesame
• shellfish (crustacea and molluscs)
• soy
• tree nuts (almonds, Brazil nuts, cashews, hazelnuts, macadamias, pecans, pine nuts, pistachios, walnuts)
• wheat
• kiwifruit.

You should always see a paediatric or allergy dietitian before removing any food groups (eg, dairy or wheat) from your, or your child's, diet unless there has been an immediate reaction to the food. Any avoidance of foods needs to happen with medical and dietitian supervision to make sure there's adequate nutrition for growth and development.

Image credit: Healthify He Puna Waiora

Symptoms, their severity and the time they take to develop may be different for each person, and from one episode to another.

Symptoms usually occur within 5 to 30 minutes of exposure to an allergen. However, some reactions can occur up to 2 hours later.

Most reactions will be mild to moderate but, in some cases, a food allergy can lead to life-threatening symptoms, known as anaphylaxis, which is a medical emergency. Some people experience anaphylaxis without first developing mild or moderate symptoms. Read more about anaphylaxis.

Mild to moderate symptoms include:

• hives/urticaria (swollen, itchy, pink/red bumps) or welts on your skin
• swelling of your lips, face or eyes
• abdominal or tummy pain
• vomiting (being sick).

Signs of a severe allergic reaction (anaphylaxis) include:

• swelling of your tongue
• swelling or tightness in your throat
• difficulty breathing or noisy breathing (wheezing)
• difficulty talking or a hoarse voice
• dizziness, loss of consciousness or collapse
• being pale and floppy (in young children).
  
  

Other reactions to food

Other reactions to foods can occur and are often mistaken for food allergy. These include food intolerances, toxic reactions, food poisoning, enzyme deficiencies, food aversion or irritation from skin contact with certain foods.

If an infant or young child has had a severe reaction, they should be treated in an emergency department. On discharge, the doctor will refer the infant or child back to their healthcare provider for follow up. This may include arranging tests and a referral to the paediatric service at your local hospital.

Your doctor or nurse practitioner should also provide parents/carers with a signed ASCIA Allergy (green) or Anaphylaxis (red) Action Plan and if a particular allergen (or food) is suspected to have caused the reaction, they should give advice about how to avoid it.

If you think you or your child has a food allergy, the first step is to see your healthcare provider. It's important to get a reliable diagnosis of food allergy before restricting a particular food in your or your child’s diet as this can affect their growth and development.

An experienced GP, nurse practitioner, paediatrician or allergy dietitian will take a history of reactions, do an examination and possibly arrange for allergy tests.

A diagnosis will be based on clinical history, such as:

• the food eaten
• whether this has previously been tolerated
• what sort of symptoms (eg, a rash or sore tummy) have happened, and
• how long after the food was eaten the symptoms developed.

If necessary, your healthcare provider may refer you for skin prick testing or order blood tests for allergen specific Immunoglobulin E (antibodies) to help to identify or exclude potential food allergy triggers. Sometimes a medically supervised food allergen challenge is done to confirm or exclude food allergy.

Currently, there's no cure for food allergy – avoiding the food is the only way to prevent a reaction. This can be challenging, especially when some foods may contain small amounts of the allergen. Your doctor, nurse or allergy dietitian can provide advice about avoiding food allergens.

Adrenaline is used to treat severe allergic reactions (anaphylaxis). It can be administered with an auto-injector such as an EpiPen(external link) to slow down or stop a severe allergic reaction. If you have a food allergy and are thought to be at higher risk of developing anaphylaxis, your doctor, pharmacist or nurse can teach you how to inject adrenaline using an EpiPen. You will also need to have an anaphylaxis action plan that documents what to do if you have anaphylaxis and when to call for help. Read more about anaphylaxis.

If you have a mild or moderate allergic reaction, treatment aims to relieve your symptoms. Antihistamines are the most commonly used medicines. Antihistamines relieve itching or hives on your skin and may need to be taken for a few weeks to reduce the build-up of histamine in the body. Examples include cetirizine and loratadine. You will also need to have an action plan that outlines what to do when you have an allergic reaction. Read more about antihistamines.

Gradual introduction of cooked allergenic foods

Researchers continue to explore new ways of more effectively treating food allergies. Treatment of milk and egg allergies now includes recommendations on introducing milk and egg in baked products, following a ‘ladder’, until the raw version of the food can be eaten safely. This has been shown to promote earlier tolerance. The allergen containing food (eg, milk or egg) is reintroduced in a stepwise approach. However, it's important that any reintroduction of foods is always led by a specialist or allergy dietitian. 

Oral immunotherapy

Oral immunotherapy treatment (OIT) is a potential treatment for food allergy. It involves giving tiny and increasing amounts of the food protein to ‘desensitise’ the immune system to that food. Results from preliminary research into immunotherapy look promising. However, more research is needed to understand the safety, benefits, cost-effectiveness, impact on quality of life and long-term outcomes. This kind of treatment should only be provided under the supervision of a clinical immunology or allergy specialist. Read more about oral immunotherapy treatment(external link).

To prevent the symptoms of food allergy you need to completely avoid the allergen. After you have identified the allergen/s you (or your child) react to, you must remove them from your (or your child’s) diet.

Here are some of the ways to minimise the risk of being exposed to a particular food allergen:

• Tell others, such as restaurant staff, about the food allergy when eating away from home.
• Don't share or swap food or utensils with others.
• Ask about food ingredients when offered food by others.
• Be aware of cross-contamination of food allergens when preparing food.
• Wash hands and surfaces to prevent cross-contamination.
• Know how to identify your food allergen and check food product labels – see the section below.
• Have a travel plan for any trips away from home – read more about travelling with food allergies.
• If the allergy is to egg, know which vaccines to avoid, eg, the yellow fever vaccine, Q fever vaccine and the Rabipur brand of rabies vaccine. Your doctor, nurse or pharmacist can provide advice and more details about these vaccines.

The Australia and New Zealand Food Standards Code requires common food allergens to be declared on a food label if the allergen is contained in the food as an ingredient, part of an ingredient, a food additive or a processing aid. Allergen information must be declared in a specific format which is known as Plain English Allergen Labelling (PEAL).

The PEAL regulations require:

• The same consistent names to be used for the common food allergens which include egg, fish, lupin, milk, mollusc, crustacea, peanut, sesame, soy, wheat, gluten and all the individual tree nuts (cashew, almond, Brazil nut etc).
• A ‘summary statement’, beginning with the word ‘contains’, that lists the allergens in the food.
• The summary statement must be located next to the ingredient list – it can be above, below or on either side of it.

For more information see the Food Standards(external link) Australia New Zealand website or Allergy New Zealand food allergen labelling(external link).

Videos

You can watch 2 videos about reading food labels for food allergens on this Food Allergy Aware webpage(external link).

Despite your best efforts to avoid particular foods, you may be exposed to a food allergen accidentally.

Be prepared for this:

• Have an allergy action plan(external link) (see below).
• Carry your adrenaline autoinjector with you at all times if you're at risk of anaphylaxis.
• Wear a medical alert bracelet or necklace so medical staff know what to do in a medical emergency.
• Learn the signs and symptoms of mild to moderate and severe allergic reactions (anaphylaxis) and know what to do when a reaction occurs.

Allergy action plans

An action plan documents and outlines the steps to follow if you have an allergic reaction, whether it's mild or serious. If you are thought to be at risk of anaphylaxis and have been prescribed an adrenaline autoinjector you need an action plan for anaphylaxis.(external link) If you're not thought to be at high risk of anaphylaxis and haven't been prescribed an adrenaline autoinjector, you need an action plan for allergic reactions.(external link)

Your healthcare provider can discuss these plans with you and you can complete them together. Find out more about the ASCIA action plans(external link).  

Support

• Allergy NZ(external link) provides information, education and support for people with allergy, parents of children with allergy, teachers and healthcare providers. 
• Allergy Today (external link)is a bi-monthly e-newsletter sharing the latest news and expert advice for managing allergies.
• Free Allergy NZ membership(external link) is available.

Here are some tips to help you support your child with a food allergy:

• Prevent contamination by washing your hands, and your child's hands, with soap and water before touching food.
• Prepare and serve foods with clean utensils and other kitchen items and on clean surfaces.
• When they're old enough, teach your child to read food labels.
• Teach your child how and when to use an adrenaline autoinjector, and to tell an adult if they're having an allergic reaction.
• After the diagnosis, focus on foods your child can safely have, rather than what they can't have.
• Start with plain foods with simple ingredients. From there you can look for new recipes that use safe ingredients (see the recipes in the more information section).
• Educate family, friends and others who will be with your child about your child's allergies.
• Be sure to tell your child's school and anyone responsible for your child about their food allergies. Read more allergy tips for children starting school.
• For children with eczema, limiting their diet to try and reduce eczema doesn't work and can lead to poor nutrition. It can also increase the chance of them developing food allergies. Regular use of steroid creams and moisturisers are the best way to manage eczema.

How you can teach your child to manage their food allergies

Teach them to:

• Identify allergens: Help your child recognize the foods that trigger their allergies. Use simple, clear language and pictures (if needed) to reinforce which foods are safe and which are not.
• Know where allergens are likely found: Educate your child about common foods that may contain their allergen, such as certain nuts, dairy, eggs, gluten, or shellfish. Talk about hidden sources of allergens in processed foods, sauces, or snacks.
• Not to share food and drinks: Encourage your child to never share food or drinks with others, especially in environments such as school, parties, or social gatherings. Sharing food can unknowingly lead to cross-contamination.
• Ask questions: Teach your child to always ask an adult (or a trusted teacher or caregiver) whether a food contains their allergen before eating it. Emphasise the importance of being cautious, even if the food looks safe.
• Avoid eating foods they're not sure about: Remind your child that if they're ever uncertain whether a food contains their allergen, it's safest to avoid it and ask an adult for clarification.
• Handle situations at parties, school, or camp: Prepare your child for social settings where food may be shared. Provide them with safe snacks to bring along and let them know it's okay to politely refuse food from others. Teach them how to explain their allergy to friends or caregivers and encourage them to speak up if they feel uncomfortable.

By teaching your child these skills, you'll help empower them to make safe choices and build confidence in managing their allergies independently.