Seafood (fish, mollusc, and crustacean) allergy factsheet

Introduction

Allergic reactions to seafood can be common. They can develop at any age but are seen more in older children and teenagers. 

Seafood is generally split into:

Fish

Including, but not limited to:

  • Anchovies
  • Barramundi
  • Cod
  • Eels
  • Flake
  • Flathead
  • Rays
  • Salmon
  • Sardines
  • Tuna

People with fish allergies are also more likely to be allergic to crocodile meat.

Molluscs

Including, but not limited to:

  • Abalone
  • Calamari, squid and octopus
  • Clams
  • Cuttlefish
  • Escargot or snails.
  • Jellyfish
  • Mussels
  • Oysters
  • Pipis
  • Scallops
  • Sea urchin

Crustaceans

Including, but not limited to:

  • Balmain and moreton bay bugs
  • Crabs
  • Crayfish
  • Krill
  • Lobster
  • Prawns and shrimp
  • Scampi
  • Yabbies.

People with a crustacean allergy may also be at risk of an allergy to edible insects, like crickets and mealworms. 

Some children are allergic to one or both categories, and others may be allergic to specific animals in each group. 

For example, your child may be allergic to salmon but can eat prawns without issues.

Seafood allergy is usually lifelong. Only around 20% of children will grow out of their allergy.

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

 Signs and symptoms

Allergic reactions to seafood can be fast, happening within minutes of exposure, or they can take up to 2 hours.

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, see your local doctor as soon as possible. 

See your local doctor as soon as possible if symptoms do not get better or you are concerned.

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.

Delayed reaction

Some children can develop a delayed reaction that takes hours or days. Symptoms of a delayed reaction can include:

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 that your child was exposed to seafood
  • what type of seafood it was
  • time of reaction
  • type of reaction
  • amount of seafood your child ate or was exposed to
  • type of exposure –touching, eating or breathing in fumes.

A specialist doctor can diagnose a seafood allergy based on your child’s:

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

Some children will grow out of their seafood allergy. 

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

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 the type of seafood they are allergic to 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 seafood

Seafood is a common ingredient in food dishes like noodle soups, curry, stir-fries, and rice, and it can be difficult to avoid. 

Some foods will visibly include seafood, such as sushi, calamari, or fish cakes. 

Seafood can also be found in other foods and products like:

  • sauces, broths, and stocks - for example, oyster and fish sauce, shrimp paste dashi, Worcestershire sauce
  • spreads, dips, and salad dressings
  • cooking oil when previously used to cook seafood, for example, in a deep fryer
  • pet food
  • supplements like fish and krill oil.

It is important for your family and your child to learn about which foods and products contain their seafood allergen and what seafood group they are allergic to. Talk to your child’s doctor about what seafood they can eat safely.

Seafood, 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 shown in bold each time they appear in an ingredient list. Packaged foods may have a warning on the label that "may contain traces of fish/crustacean/mollusc".

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

Talk to your child’s doctor about whether these foods are safe.

Tell staff about your child’s specific seafood allergy to avoid exposure when eating out.

If you cannot confirm that a food does not contain or has not touched your child’s specific seafood allergen, it is safest for your child to avoid it.

Education

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

Parents of younger children will need to read ingredient lists and learn to identify seafood allergens in foods and drinks.

Older children can be supported in learning to read ingredient lists and identify seafood allergens in foods and drinks. 

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.