• Allergies

Can You Develop a Fish Allergy Later in Life? What to Know

Published: March 17, 2025
Updated: March 17, 2025
4 mins

As people age, the immune system may change and react to certain foods and allergens differently. Some of the most common allergens among adults in the U.S. are finned fish, tree nuts, shellfish, and peanuts. Unlike most allergies, a fish allergy can often develop later in life. 

Today, fish is one of the top food allergens affecting adults in the United States. Varying degrees of severity can make the allergen more difficult to manage than others. Some people may experience symptoms from the aroma of cooked fish, while others may only experience them from eating certain types of fish.

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What is a Fish Allergy?

A fish allergy is an immune response to proteins in fish. An allergic reaction occurs when the immune system perceives certain proteins in fish as a threat. People often confuse a fish allergy with a shellfish allergy. 

While the two are often prepared together, the proteins in each type of seafood are different. However, most seafood does contain the protein parvalbumin. Those with a fish allergy may also be allergic to other metabolic enzymes in fish like tropomyosin.

The following are a few foods that may trigger fish allergy symptoms:

• Cod

• Tilapia

• Catfish

• Whiting

• Flounder

• Perch

• Haddock

What are the Symptoms of Fish Allergy?

The severity of symptoms varies for those with a fish allergy. Initially, you may not notice moderate symptoms like mild itchiness in the mouth and throat.

Other symptoms of a fish allergy someone may experience:

• Swelling in the lips

• Hives

• Vomiting

• Nausea

• Dizziness

• Drowsiness

• Redness

• Trouble breathing

Those with a severe allergy may also experience symptoms from the distant smell of fish or non-seafood items that have made contact with fish. Anaphylaxis is a life-threatening reaction to allergens. 

Be sure to seek emergency assistance immediately if you have trouble breathing or experience the following severe symptoms:

• Throat constriction

• Wheezing

• Weak pulse

• Paleness

• Fainting

Who is Most Likely to Develop a Fish Allergy?

If multiple people in your immediate family have a fish allergy, you may be more likely to develop one later in life. However, it is still possible to develop an allergy if no one else in your family does. 

Different countries also consume different types of fish. If you live in the U.S., a healthcare provider may be more likely to confirm a fish allergy from exposure to cod, salmon, catfish, and tuna. You may not know you are allergic to fish if symptoms are only triggered by eating other fish species like carp, trout, and herring, which may be more common in Europe and Asia. 

Differences Between Childhood and Adult Allergies

Fish allergies are more common in adults and teenagers than in young children. However, children may be more likely to outgrow a fish allergy as they enter adulthood. Adults with a fish allergy are less likely to see it change over time. However, there are rare cases where a fish allergy can turn into fish intolerance over time as an adult.

A fish allergy is more commonly diagnosed in adults in North America. In other places around the world where fish is a staple of more dishes, you may encounter more fish allergies in both adults and children. For example, fish allergies are more common in children in China, the Philippines, and Vietnam. 

On the other hand, childhood fish allergies are much lower in countries like Norway, Ghana, and Germany. While these countries still may have some staple fish dishes, exposure may be lower for other reasons.

How to Treat Symptoms of a Fish Allergy

The best way to treat a fish allergy is to avoid fish as much as possible. When eating out, mention your fish allergy to restaurant staff, even if your dish doesn’t contain fish products. This can help prevent accidental exposure. Another tip is to thoroughly read through ingredient lists on all of the foods you purchase.

A healthcare provider may recommend carrying an Epipen (epinephrine auto-injector) with you if you have a fish allergy. Those with a fish allergy can use an Epipen to keep symptoms at bay until medical attention arrives. Antihistamines like Benadryl may help to reduce mild symptoms.

However, a healthcare provider may also recommend wearing a medical alert bracelet if exposure to fish is potentially fatal. 

How Do You Know if a Food Has Fish?

The U.S. Food and Drug Administration (FDA) requires that products clearly state on the label whether a food contains fish. However, oftentimes a manufacturer will list the type of fish instead of the word “fish.” Products with the warming “may contain fish” or “produced in a plant that uses fish in other products” indicate that the risk of cross-contamination is high even if fish is not a direct ingredient in the product.

Not all fish sources may trigger symptoms in those with a fish allergy. Some fish products, like gelatine in vaccines, may not cause an allergic reaction in someone with a fish allergy. Still, let a healthcare provider know about all of your allergies before receiving a vaccine or being prescribed a medication.

Foods that May Cross-React with Fish

Other seafood options, like shellfish, are often cooked in close corridors with finned fish. It’s common for people with a finned fish allergy to not be allergic to shellfish. However, eating shellfish like shrimp, crab, and lobster can have a higher risk of cross-contamination. 

Other foods fish may cross-react with and cause allergy symptoms that you may not be aware of including the following:

• Salad dressing

• Hot dogs

• Deli meats

• Worcestershire sauce

• Marshmallows

• Wine 

• Beer

How a Fish Allergy is Diagnosed

Don’t hesitate to seek emergency care when symptoms appear. A healthcare provider can give you tips on the proper precautions and managing exposure. If you suspect you have an undiagnosed fish allergy, a healthcare provider or licensed allergist can run a skin prick or blood allergy test. 

A skin prick test determines if you have a food allergy by placing a small amount of allergen on the surface of the skin. If a visible reaction appears, a healthcare provider may determine you have an allergy to the allergen. However, this is a chance of a false positive or false negative.

How to Manage a Fish Allergy

Some people may have an allergy to one type of fish and not others. The most common fish allergens in the United States are tuna, salmon, and halibut. The likelihood of coming into contact with one type of fish over another may vary regionally in the U.S. and internationally. 

Even if you are not diagnosed with an allergy to one type of fish, exercise caution when consuming all types of fish. Most healthcare providers may advise against consuming other types of fish to prevent the risk of cross-contamination. If your allergy is severe, it may be best to avoid eating at seafood restaurants.

Where Can I Learn More About Food Allergies?

Food allergies can affect the kinds of restaurants a person frequents, how food is prepared, and the overall dining experience. At LifeMD, a healthcare provider can give you guidance on how to manage a fish allergy and how to keep yourself safe from potential exposure.

Get started today taking action to protect yourself from potential allergens.

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