Soy allergy factsheet

Introduction

Products like soy milk and tofu are made from soybeans. 

Most children will grow out of their soy allergy, but some will have it for life.

Like any other allergy, it is important to talk to your child's doctor before reintroducing foods that have caused an allergic reaction.

 Signs and symptoms

Allergic reactions can be fast and happen within minutes of exposure to soy.

Reactions can include:

  • hives or welts on the skin
  • redness of the skin
  • vomiting and stomach ache
  • tingling and swelling of the mouth, lips, face, and eyes.

If your child is showing signs of an allergic reaction for the first time, if symptoms do not get better, or if you are concerned, see your local doctor as soon as possible.

Anaphylaxis

Some children can have a more severe allergic reaction called anaphylaxis.

Signs of anaphylaxis include: 

  • wheezing, difficult, or noisy breathing 
  • swelling of the tongue
  • swelling or tightness in the throat
  • a persistent cough
  • difficulty talking or a hoarse voice
  • dizziness
  • becoming pale and floppy in young children
  • collapsing.

If your child has signs of anaphylaxis, you should:

  • follow your child’s ASCIA action plan for anaphylaxis if you have one
  • use an EpiPen or Anapen, if available
  • call Triple Zero (000) for an ambulance.

Diagnosis

If you think your child has had an allergic reaction that is not anaphylaxis, write down the following and see your local doctor as soon as possible:

  • time your child was exposed to the soy product
  • time of reaction
  • type of reaction
  • amount of soy product eaten.

A specialist doctor can diagnose a soy allergy based on your child's:

  • medical history
  • signs and symptoms
  • results from allergy tests.

Some children will grow out of their soy allergy. 

A food challenge can be done to figure out whether your child has grown out of their allergy and whether soy can be reintroduced to their diet safely. Food challenges are done under the supervision of a doctor in a medical setting. 

Treatment

Your child's doctor will find the best possible treatment for their allergy based on their individual health needs. In most cases, your child must carefully avoid soy in their diet. 

Your child’s doctor will develop an ASCIA Action plan to share with anyone who cares for your child, including parents, carers, childcare and schools. 

ASCIA Action plans are used to manage allergies and allergic reactions safely.

Children at risk of anaphylaxis will also need an adrenaline autoinjector, also known as an EpiPen® or Anapen®.

 Management

Common sources of soy

Soy is a common ingredient in food, so it can be difficult to avoid. 

Some foods will visibly include soy, like tofu, tempeh, or edamame.

It can also be in other products like:

  • infant formula
  • foods labelled as vegetarian, dairy-free, plant-based or vegan
  • bread and other baked goods that are made using soy flour
  • mayonnaise, margarine, packaged sauces, gravy mixes and flavourings
  • pre-prepared meats with filler - for example, hot dogs, burger patties and chicken nuggets

Products like soy sauce, miso, and tamari are commonly used in noodle soups, curry, stir-fries, and fried rice.

Soy is also commonly used to replace dairy in products like yoghurt and milk. It is important to always check the package and ingredient list of all foods. 

Infant formula and soy allergy

If your baby is exclusively breastfed, they will not usually have soy in their diet until you start introducing solids at around six months old.

Most common infant formulas are made from cow's milk or soy products. 

Formula-fed Babies who have both a cow's milk and soy allergy will need special infant formula that a doctor can prescribe.

Soy, food labels and eating out

It is important to always check the package and ingredient list of all foods your child eats.

In Australia, allergens are bolded each time they appear in an ingredient list. Packaged foods may have a warning on the label that they "may contain traces of soy."

This means the food is made in a facility that also makes foods that contain soy. Talk to your child’s doctor about whether they should avoid these foods.

Always tell the staff that your child has a soy allergy when eating out. This will help you find safe foods and avoid contamination. 

If you cannot confirm that food does not contain soy, it is safest for your child to avoid it.

Talk to your child’s doctor about what foods containing soy are safe if you are unsure.

Education

Some children are more at risk of having a soy allergy. Risk factors include:

The most important thing you can do is support your child in avoiding soy in their diet. You can also educate your child, family, and friends about allergies, reactions, and what to do in an emergency.

Parents of younger children must read ingredient lists and learn to find soy in foods and drinks.

Older children can be supported in learning to read ingredient lists and find soy in foods. 

This can help keep children safe and encourage them to be more independent and confident about their diet and health as they grow.

Resources and more information

The Australian Society of Clinical Immunology and Allergy (ASCIA)

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The Australian Society of Clinical Immunology and Allergy (ASCIA)

Biography
Provides resources including fact sheets, e-training and information on locating allergy specialists.
Related Links
Allergy & Anaphylaxis Australia - Your trusted charity for allergy support

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Allergy & Anaphylaxis Australia

Phone1300 728 000
Biography
Provides valuable updates and tips for dealing with food allergies.
Related Links
Food Standards Australia and New Zealand (FSANZ)

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Food Standards Australia and New Zealand (FSANZ)

Biography
Part of the Australian Government's Health portfolio and provides detailed information on food labelling.
Related Links
Last updated Tuesday 18th June 2024

Disclaimer

This factsheet is provided for general information only. It does not constitute health advice and should not be used to diagnose or treat any health condition.

Please consult with your doctor or other health professional to make sure this information is right for you and/or your child.

The Sydney Children’s Hospitals Network does not accept responsibility for inaccuracies or omissions, the interpretation of the information, or for success or appropriateness of any treatment described in the factsheet.

© Sydney Children’s Hospitals Network 2024


This factsheet was produced with support from John Hunter Children's Hospital.