Fish allergy

What is fish allergy?

In fish allergy, the immune system reacts to proteins in fish. The most important is parvalbumin, a protein in fish muscle that withstands heat and is found in almost all species of fish. In cod it is called Gad c 1. Because parvalbumin is so similar between species, most people with fish allergy react to several kinds of fish.

Fish allergy often starts in childhood and is usually lifelong.

Symptoms

• Itching and swelling in the mouth
• Hives and redness
• Vomiting and stomach ache
• A runny nose, coughing and breathing difficulties
• A severe allergic reaction (anaphylaxis)

Some people react even to the steam when fish is being cooked.

Where fish is found

Fish is found in fish fingers, fish balls, sushi, surimi (crab sticks), fish roe, fish sauce in Asian dishes, Caesar dressing with anchovies and some stocks. Fish is one of the allergens that must always be declared on the ingredients list.

Cross-reactivity

Because of parvalbumin, allergy to cod often means allergy to salmon and other fish. The amount of parvalbumin differs between species, however – tuna and mackerel contain less, and some people with fish allergy tolerate them after investigation by a doctor. Fish allergy and shellfish allergy are different allergies.

How to get tested

Cod (allergen code f3) is included in our Fish and shellfish allergy test, together with salmon and shrimp. The test shows whether you have IgE antibodies to cod.

Frequently asked questions

Can I take fish oil if I am allergic to fish?

Purified fish oil, such as omega-3 supplements, generally contains no or very little protein. Still, talk to your doctor if you have had severe reactions.

Do people outgrow fish allergy?

It happens, but it is uncommon. Fish allergy is more often persistent than milk and egg allergy.