Fish and shellfish allergy

Greater numbers of people are now finding they are allergic or intolerant to fish and/or shellfish and at whatever stage you acquire this allergy it is likely that you will have it for life.

Many people who are shellfish-allergic may be able to eat fish, and vice versa. But you should be aware that there is a risk of cross-contamination in restaurants, markets and open fish counters so if you do suffer from either allergy it is important that you keep this in mind.

Fish allergy

The most common kinds of fish that people are allergic to are: Salmon Tuna Halibut

It is generally recommended however, that individuals who are allergic to one species of fish avoid all fish.

Shellfish allergy

An allergy to shellfish is more common and there are generally 4 types of shellfish that people can react to. These being:

• Crustaceans (e.g. crab, lobster, crayfish, shrimp, prawn)
• Molluscs – Bivalves (e.g. mussels, oysters, scallops, clams)
• Molluscs – Gastropods (e.g. limpets, periwinkles, snails)
• Molluscs – Cephalopods (e.g. squid, cuttlefish, octopus)

People who have reacted to one type of shellfish (e.g. crab) are likely to react to other members of the same group (in this case, other crustaceans). It is therefore important for you to avoid all shellfish within the group that you have an allergy. Allergy tests may help to predict which types of shellfish you will react to, but if in doubt it may be best to avoid all shellfish.

Symptoms

The symptoms of food and shellfish allergies can range from the relatively mild to life threatening. However the likely effects are:

• Nausea
• Diarrhea
• Abdominal cramps
• Wheezing
• Rhinitis
• Urticarial rashes
• Dramatic swelling
  

In severe cases, an allergy can lead to anaphylaxis where the symptoms could include a swollen throat (airway constriction), rapid pulse, shock and dizziness or lightheadedness. This can be life-threatening and it is important for people who may be at risk of having a severe allergic reaction to carry injectable epinephrine (such as an EpiPen or Anapen) with them at all times. It is also advisable to wear an identification bracelet stating the food sensitivity.

Food to avoid

In addition to avoiding the fish or shellfish you are allergic to, you should also be aware that traces of fish/shellfish can be found and used in many other products. Therefore, as well as scrutinising food packaging labels you need to be careful when eating out. This is particularly important if any of the food you eat is fried since the oil used to cook shrimp could also be used to cook fried chicken or French fries.

Common foods that should be avoided include:

• Paella
• Bouillabaisse
• Gumbo ( a Tex Mex dish)
• Frito Misto ( a mixed fried fish dish from the Med)
• Fruits de mer (seafood)
• Kedgeree
• Oriental foods since they tend to contain lots of different kinds of fish
• Stocks and soups since fish forms the base of many of these
• Surimi (a processed seafood product) that is usually made from white fish but may contain shellfish extract. Surimi can be present in processed foods e.g. pizza toppings
• Caesar salad dressing which will normally contain anchovies
• Worcestershire sauce since it may contain anchovies
• Fish sauce, words to look out for are Nuoc Mam and Nam Pla (it can also be made with shellfish)
• Menhaden, a type of fish caught along the Atlantic coast which is used in a variety of products including vitamins, soap, lipstick, paint, insect spray, and waterproofing
• Oriental sauces, pastes and prepared meals since many can contain fish/shellfish related ingredients.

The cod worm

The cod worm (Anisakis) is a worm-like parasite which is relatively common in Spain and can cause urticaria, stomach upsets or sometimes anaphylaxis when present in fresh cephalopods, hake, anchovy or cod. Some people who think they may have a seafood allergy may just be having an allergic reaction to the cod worm parasite. Therefore, if you react to a particular fish once, but later eat it with no problem this could be due to a cod worm allergic reaction.

It is therefore important that you speak to a health professional to confirm this.

Information written by the talkhealth medical panel

Last Reviewed: 12 January 2011
Next Review Date: 12 January 2013