A Parent’s Guide to Finned Fish Allergy

Learn what finned fish allergy is, symptoms of fish allergy, how finned fish allergy is different from shellfish allergy, and how fish allergies are more common in adults than babies and young children.

Fish allergy is one of the 8 most common food allergies in the United States. But although children can develop a fish allergy at a young age, fish allergies are more common in adults, and around 40% of people with a fish allergy have their first allergic reaction to fish as adults. 

Fish allergies tend to be lifelong, and they have the potential to cause life-threatening anaphylaxis.

Here’s what parents need to know about fish allergies, also known as finned fish allergies. 

What Is a Fish Allergy?

Normally, our immune systems defend and protect us from harmful invaders, like certain viruses and bacteria. But when someone has a fish allergy, their immune system over-defends the body against certain types of finned fish proteins, and mistakenly treats these fish proteins as harmful invaders.

Their immune system makes special allergy antibodies called IgE antibodies to finned fish proteins to help fight them off. These IgE antibodies trigger symptoms of an allergic reaction whenever the person eats fish or a food containing fish.

Learn more from Food Allergy Research & Eduction about managing a fish allergy:

Types of Fish Allergy

When someone has a fish allergy, they may have an allergy to one or more specific types of finned fish. Since over 50% of people with one fish allergy are allergic to at least one other fish, allergists often recommend that people with one fish allergy avoid all types of fish. It may be possible for someone with one fish allergy to safely eat certain other types of fish, but they’ll need specific allergy testing to be sure. 

Some common types of fish allergy include: 

  • Salmon allergy
  • Tuna allergy
  • Catfish allergy
  • Cod allergy
  • Anchovy allergy
  • Bass allergy
  • Flounder allergy
  • Haddock allergy
  • Halibut allergy 
  • Herring allergy 
  • Mahi mahi allergy
  • Snapper allergy 
  • Pollock allergy
  • Pike allergy
  • Perch allergy
  • Tilapia allergy
  • Swordfish allergy
  • Trout allergy
  • Grouper allergy

This is not a complete list of the types of finned fish allergy. Allergies can develop to any type of fish—and there are over 20,000 species of fish in the world.

Symptoms of a Fish Allergy Reaction

Symptoms of a fish allergy usually develop seconds to minutes after eating finned fish, and almost always within 2 hours.

Symptoms of a fish allergy can include:

  • Hives (red raised bumps)
  • Skin redness
  • Vomiting
  • Itching
  • Itchy, watery eyes
  • Swelling of the face, lips, eyes, tongue, or throat
  • Runny nose
  • Congestion
  • Trouble breathing
  • Trouble swallowing
  • Wheezing
  • Nausea
  • Diarrhea
  • Abdominal pain
  • Dizziness
  • Fainting

Fish allergic reactions can range from mild to severe. When the symptoms of a fish allergic reaction are severe, and involve more than one organ system, the reaction is classified as anaphylaxis. And anaphylaxis can be life-threatening.

Swelling of the face, tongue or throat, wheezing, breathing difficulty, and significant cardiovascular symptoms may be signs of an anaphylactic reaction. Call 911, and give epinephrine (use an Epi-Pen) immediately, if your child shows signs of anaphylaxis. 

Finned Fish Allergy Testing

Finned fish allergies can be diagnosed through:

  • A blood test (where your child’s blood is checked for IgE antibodies that respond to fish proteins)
  • A skin prick test (where your child’s forearm is pricked with a needle containing fish protein, then monitored to see if an allergic reaction develops around the area where their skin was pricked)
  • An oral food challenge (where your child eats small amounts of fish under an allergist’s supervision, to see if they develop an allergic reaction. This is the most accurate way to diagnose a finned fish allergy.) 

These tests can be done with specific types of fish, to determine whether or not your child has a specific fish allergy. Remember, though, that there are thousands of types of fish, so it’s impossible to test for every type of fish allergy. 

Finned Fish Allergy Vs. Shellfish Allergy

A finned fish allergy is completely different from shellfish allergy, because finned fish and shellfish are in different biological categories. 

If your child has an allergy to a fish with fins (such as cod or tuna), this doesn’t always mean that they’ll also have an allergy to shellfish (like shrimp, crab, lobster, clams or mussels). Having to avoid finned fish doesn’t mean your child will need to avoid shellfish. And if they do have a shellfish allergy, that’s completely independent of their fish allergy.

This is why a “fish allergy” is also called a “finned fish allergy” — to show that a fish allergy isn’t an allergy to all seafood. 

Still, people with finned fish allergies should avoid going to seafood restaurants. Even if they order a dish with only shellfish, or without any seafood, there’s a high risk of cross-contamination (a high risk that finned fish got mixed in the dish accidentally, which could cause a finned fish allergic reaction). 

And even touching finned fish, or being exposed to the steam from finned fish cooking, could trigger a fish allergy reaction—another reason to avoid places where seafood is being cooked.

Fish Allergy Trends

Finned fish allergies are one of the top 8 food allergens in the United States.

Fish allergies can develop at any age. Around 0.5%-0.6% of children have a fish allergy. 

Overall, though, fish allergies tend to be adult allergies. Around 40% of people with a fish allergy had their first allergic reaction to fish as adults. 

And according to a study by Dr. Scott Sicherer and others, fish allergies are more common in adults than children, and far more common in children ages 6-17 than in young children ages 0-5. 

Also, fish allergy is a lot less common in young children than allergies to peanut, egg, and milk (the top three childhood food allergies). 

But no matter when they develop, fish allergies usually aren’t outgrown. Rather, fish allergies tend to be lifelong. 

Which types of fish most commonly cause allergic reactions? According to Dr. Sicherer’s study, salmon, tuna, catfish, and cod allergies are the most common fish allergies. 

Since fish is one of the top 8 allergens, U.S. federal law requires all packaged food products that contain fish to clearly state that they contain fish on the label. Fish products must also clearly state which type of fish they contain (ex. “Contains: Salmon.”)

Managing Fish Allergy

People with fish allergies need to strictly avoid the type(s) of fish they are allergic to, because eating any amount of finned fish could potentially trigger an allergic reaction. As mentioned above, many allergists will recommend avoiding all fish, unless a specific fish allergy test shows that your child doesn’t react to a certain type of fish. 

Avoiding Hidden Fish

Even with the requirements for fish to be labeled on packaged foods, avoiding fish can be difficult. This is because many foods contain hidden fish. Always read the labels carefully to keep your child safe!

Some foods that may contain hidden fish include:

  • Barbecue sauce
  • Caesar salad/Caesar dressing 
  • Worcestershire sauce
  • Thai fish sauce (Nam pla)
  • Bouillabaisse (a stew-like seafood dish that contains both finned fish and shellfish ingredients) 
  • Caponata (eggplant relish)

You’ll also need to avoid fish gelatin (made from fish skin and bones), fish oil, fish broth, fish stock, and fish sticks.

Even “artificial” or “imitation” fish, or “artificial” or “imitation” shellfish (like “imitation crab”) may contain very real finned fish. So, avoid products like these. (The fish in these “imitation” products is sometimes called surimi, and it’s made from pollock.)

Avoiding Cross-Contamination and Fish Mislabeling

You’ll need to avoid cross-contamination, or the accidental mixing of a food containing fish into a food without fish. Watch out for foods that were processed on the same equipment as foods that contain fish (these foods will say “may contain fish” or “processed on equipment that also processes fish” on their labels.) 

As mentioned above, avoid seafood restaurants, as they also pose a high risk of cross-contamination (and as their steam from cooking fish may trigger an allergic reaction). 

Thai, Chinese, Japanese, Vietnamese, and Indonesian restaurants are also high-risk for people with fish allergies. Fish features heavily in these cuisines, so there is a high cross-contamination risk at these restaurants as well. 

And anywhere that fries fish in oil could pose another risk of cross-contamination. Proteins from the fish could remain in the oil and mix with the other food. If fish is fried in oil, your child will need to avoid any food that was cooked in the same oil as the fish. 

In addition, restaurants of all kinds sometimes mislabel fish on their menus (to serve cheaper types of fish). So, even if an allergist has cleared your child to eat a type of fish, it’s best to avoid all finned fish at any restaurant.

At any restaurant, be sure to alert your waiter and the chef that your child has a fish allergy, including the specific type(s) of fish they are allergic to. This will help you avoid cross-contamination and mislabeled fish.

Even grocery stores and supermarkets sometimes sell mislabeled fish at their fish counters (because of dishonest suppliers), so it’s best to avoid all fish from these counters when your child has a fish allergy.

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All health-related content on this website is for informational purposes only and does not create a doctor-patient relationship. Always seek the advice of your own pediatrician in connection with any questions regarding your baby’s health.

These statements have not been evaluated by the Food and Drug Administration. Products are not intended to diagnose, treat, cure or prevent any disease.

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