Food allergy

What are food allergies?

Food allergies involve an immune response to certain foods. Symptoms of food allergy include wheezing, stomach upsets and skin rashes. The most common food allergens are egg, milk and peanut (75 per cent), with most of the rest caused by nuts, fish, shellfish, wheat and soy products. Anaphylaxis is a severe allergic reaction and can be life-threatening, although risk of a fatal reaction is extremely small.

Symptoms

Food allergy symptoms start within minutes of eating the food or up to two hours later. An allergic reaction can occur with only tiny amounts of a food, but resolve over the course of hours. The reactions will not reoccur if the trigger is avoided. Here are some common symptoms:

• Skin reactions: Hives (most common), swelling and a rash around mouth – this can also be seen with strawberry, citrus and tomato consumption, but this is an intolerance rather than an allergic reaction.
• Gastrointestinal reactions: Vomiting, nausea, diarrhoea, stomach cramps, itchiness or swelling of the mouth.
• Respiratory reactions: Wheezing, sneezing and a runny nose.
• Cardiovascular reactions: Dizziness, pale skin, confusion and loss of consciousness (fainting).

Diagnosis

Food allergies are best determined on the story surrounding a bad food reaction. Testing for food allergies (blood or skin prick) should be used to confirm a suspected immediate food allergy:

• A positive tests means your child is likely to be allergic to the food in question.
• A negative result means your child is very unlikely to be allergic to the food. Occasionally, if the story is compelling, then a supervised challenge may be necessary.
• Blood and skin prick testing are not useful for other food reactions.

Testing other foods

Foods that are regularly eaten without reaction should not generally be tested. Testing to foods that have not been ingested may be beneficial if negative. This means there is a very low risk of reaction if this food is eaten. However, there is a risk of false positive results with both skin and blood testing for food allergies. This is particularly high in children with other allergic diseases like eczema, so caution must be taken with interpretation of results.

The only way to be certain about food allergy is if there is a reaction on eating the food. There is now strong evidence the prolonged avoidance of food (peanut) increases the risk of allergy.

Managing food allergies

• If your child is allergic to a certain food, it must be avoided at all times.
• In infants and young children, be careful when eliminating foods from their diet to ensure nutritional needs are still being met. A doctor should always supervise any dietary restrictions, perhaps with the help of a dietician.
• It can be difficult to ensure your child does not accidentally eat the banned food. It will require vigilance on your part. This can be easier to do when your child is young and at home with you. When in the care of others, appropriate education of carers will reduce your child’s risk.
• Your child must never share food with other children.

Read food labels

• Always read food labels.
• Become familiar with technical or scientific names. Some examples include:
  • Milk (casein, sodium caseinate, whey, milk solids)
  • Egg white (albumin)
  • Wheat (gluten)
  • Peanuts (peanut butter, mandalona, peanut flour, ground nuts, peanut oil, vegetable oil, vegetable shortening, vegetable protein, vegetable almond paste).
• Try phoning a food manufacturer to confirm what ingredients are contained in their product.
• A dietician may be able to help if you are uncertain about the contents of a particular food.
• Labels such as “may contain” generally do not have any of the stated food protein and may be suitable for consumption. Ask your doctor or dietitian if you have concerns.

Take safety precautions

• Always ask about ingredients when you and your child eat out at restaurants or at other people’s homes.
• If the person is uncertain or there is any doubt, do not feed the food to your child.

Inform and educate

• Any person looking after your child, such as family members, neighbours, friends and teachers must know:
  • About your child’s allergies
  • What precautions to take
  • What to do if accidental ingestion does occur.
• If your child has had a severe reaction (anaphylaxis) or is allergic to peanuts/treenuts, they could consider wearing a MedicAlert bracelet.

Medications

No matter how careful you are, the chances are your child will have an accidental ingestion at some point. If your child has only had mild reactions they will probably not need any medications. Antihistamines can sometimes help to reduce symptoms.

For children who have had a severe reaction or are allergic to peanuts/treenuts, an EpiPen® (adrenaline) should be prescribed.

Some things to remember with the EpiPen® include:

• An EpiPen® can be life-saving and must be carried with your child at all times.
• You and anyone who looks after your child must know how to administer it and be comfortable doing so.
• The EpiPen® must not be left in heat (e.g., in a car) and is sensitive to light.
• They should not be used if discoloured or cloudy – periodically check that it is has not expired.
• Consider having an EpiPen® both at home and at school.

The EpiPen® must be given immediately after anaphylaxis occurs and your child should be taken straight to a hospital or doctor, preferably by ambulance.

The effects of the EpiPen® can start to wear off after about 20 minutes. A second dose can be given if symptoms continue beyond this and you have not yet reached the hospital or doctor.

When to seek help

See your GP if your child has any common symptoms.

In an emergency, call Triple Zero (000) and ask for an ambulance.

If you're not sure whether to go to an emergency department, call 13 HEALTH (13 43 25 84) and speak to a registered nurse.

More information

• Allergy and Anaphylaxis Australia
• Australasian Society of Clinical Immunology and Allergy
  • Food allergy
  • Other adverse reactions to food
  • Allergy prevention.

Developed by the Immunology and Allergy Department, Queensland Children’s Hospital. We acknowledge the input of consumers and carers.

Resource ID: FS281. Reviewed: January 2018.

Disclaimer: This information has been produced by healthcare professionals as a guideline only and is intended to support, not replace, discussion with your child’s doctor or healthcare professionals. Information is updated regularly, so please check you are referring to the most recent version. Seek medical advice, as appropriate, for concerns regarding your child’s health.