Allergy - Seafood allergy (includes fish and shellfish)

What is seafood allergy?

Seafood allergy is a reaction that happens soon after a child is exposed to seafood or foods containing seafood. Both fish and shellfish allergy is more common in adults than in children and tend to be lifelong.

An allergy to one type of seafood does not mean a child has an allergy to all types of seafood. A child who is allergic to only one or two types of seafood may be able eat other types of seafood without an allergic reaction. Steam formed by cooking fish can cause allergic reactions in very sensitive children. This means the whole family may need to avoid eating seafood, or the seafood may need to be cooked outside.

How is seafood allergy diagnosed?

You can have your child tested with a blood or  skin prick test. Not every child with a positive allergy test will develop symptoms of an allergic reaction after being exposed to seafood. If you think that your child has a seafood allergy, you should not give your child seafood, unless you have been advised to do so. Your doctor may also suggest that your child has a challenge with seafood in hospital to prove that they will not react

What are the symptoms of fish allergy?

Reactions can range from mild to severe.

Mild to moderate reactions may include any one of the following:

• hives or welts

• selling of the tongue

• swelling of the lips/face/eyes

• tingling of the mouth

• abdominal pain or vomiting.

Severe reactions (anaphylaxis) may include any one of the following: 

• difficulty/noisy breathing

• swelling of the tongue

• swelling or tightness in the throat

• difficulty talking and or hoarse voice

• wheeze or persistent cough

• persistent dizziness or collapse, pale and floppy (in young children).

Sometimes symptoms of a severe reaction happen without symptoms of a milder reaction first. It is rare (but possible) for severe symptoms to occur alone without hives and/or vomiting.

What is an Epipen?

An Epipen, also called an autoinjector is an emergency device that injects a dose of adrenaline into the muscle in the leg. They are used to treat severe reactions to nuts (anaphylaxis). The drug adrenaline reverses the severe allergic reaction and can be lifesaving.

Should my child carry an adrenaline autoinjector?

All allergists agree that children who have had a serious reaction involving their breathing should have an adrenaline autoinjector. The need for other children to have an adrenaline autoinjector depends on many factors which you can discuss with your doctor. If you have an adrenaline autoinjector it is very important that you understand how and when to use it and that you have a written anaphylaxis action plan from your doctor.

What sorts of fish can my child be allergic to?

There are 2 main types of fish which can trigger allergic reactions:

• fish  with backbones

• fish without a backbone often called shellfish

Fish with backbones

From an allergy point of view, these fish may be divided into 6 groups:

Group 1   shark, flake and sweet William

Group 2   sardines, pilchards and anchovies

Group 3   salmon, pike and trout

Group 4   cod, hake and haddock

Group 5   tuna, mackerel, snapper, pink snapper, perch, barramundi, bream, flathead and whiting

Group 6   sole, flounder, halibut

There are many different types of fish. The names given to fish can vary from place to place so make sure that the fish you buy is correctly named.

If your child is allergic to a fish in one of the groups it may be possible to find a fish in another group which does not cause an allergic reaction .Your doctor can sort this out with allergy skin tests using small pieces of the fresh fish followed by an oral challenge.

Fish without backbones (or Invertebrates)

• Crustaceans e.g. prawns, shrimps, lobster, crayfish, crab, yabbies, bugs

• Molluscs e.g. snails, abalone, mussels, clams, oysters, pipis, cockles

• Cephalopods e.g. octopus, cuttlefish, squid, calamari

• Gastropods e.g. sea slugs, garden slugs and snails

The  allergens in invertebrates(fish without backbones) are not destroyed by cooking. If your child is allergic to any of these invertebrates, all invertebrates should be avoided. Children who are allergic to invertebrates may not be allergic to fish with backbones.

What foods have fish in them?

Fish is used in fish fingers, calamari rings, fish burgers and fish nuggets. It may be difficult to find out what type of fish is in a specific product and the fish used may vary from time to time.

Fish is part of many dishes, sauces, salad dressings, pastes and cracker biscuits.

Glucosamine supplements (used for arthritis) may be derived from crustaceans and should be avoided by people with allergies to crustaceans.

Possible foods with fish are:

Tips for avoiding fish and seafood

Check the following for exposure to fish and seafood:

• BBQ surfaces which haven’t been cleaned after cooking fish.

• Cooking oil that fish has been cooked in before.

• Batter which has had fish dipped into it.

• Seafood platters which contain a mixture of fish and seafood.

• Pet food that your child may access.

Contacts for more information:

• The Sydney Children’s Hospital Network website has more fact sheets on Allergies: www.schn.health.nsw.gov.au/parents-and-carers/fact-sheets
• Australian Society of Clinical Immunology and Allergy (ASCIA) www.allergy.org.au
• The patient support group Anaphylaxis Australia offers valuable updates and tips for dealing with food allergies (www.allergyfacts.org.au).
• Food Standards Australia and New Zealand for information on food labelling www.foodstandards.gov.au