Unreliable Diagnostics for Fish Allergies


Diagnostics are important for food allergies because they help determine whether symptoms confirm an allergy or a different concern, and they can specify the allergen. A diagnosis helps you know your child’s allergy so you can manage it and work to prevent reactions.

Parents rely on a diagnosis being accurate, because food allergies can be life-threatening. Unfortunately, current news in the field of food allergy diagnostics is that fish allergy testing is not reliable. Fish is one of the top 8 most common food allergens, and inaccurate testing could be dangerous.

The Problem

One of the ways to diagnose a food allergy is to perform a skin prick test. But an evaluation of the fish preparations used in this type of testing varied in the amount of major allergens they contained. The allergens were not even detected in some of the preparations. Another problem is that people can be allergic to some types of fish but not others. There are only commercial preparations for four out of the hundreds of fish species that have allergens.

This information was discovered through an evaluation by the Australian Institute for Tropical Health and Medicine of James Cook University.

Potential Consequences

What could happen from unreliable fish preparations is that skin prick test results won’t necessarily be valid. The results might show that your child does not have a fish allergy, yet it’s possible for this result to be a false negative. If the preparation doesn’t contain any of the allergen or not enough to create a reaction, the results could be incorrect.

If someone doesn’t know they are allergic to fish and eats it, they could potentially face severe and even life-threatening allergic reactions.

Fish Allergy Symptoms

A fish allergy is not as common as other food allergies, yet it is a serious one that often causes anaphylaxis. This severe allergic reaction can lead to death, because it affects the ability to breathe and can send someone into shock.

Anaphylaxis from finned fish happens often, yet it is less common than other symptoms of fish allergy. These include:

  • Hives on the skin

  • Asthma

  • Digestive symptoms, including stomach cramps, nausea, indigestion,  diarrhea or vomiting

  • Headaches

  • Nose congestion or running; sneezing

If you have noticed any of these symptoms after your child has eaten fish or a fish product, they may have an allergy to fish. If a skin test comes up false but you still notice reactions to fish, the results may have been incorrect.

Alternative Testing

If your child got a negative result from a skin test but you suspect they may have a fish allergy, you could talk to your allergist about an oral food challenge. Your child eats a small amount of the allergen under medical supervision to see if there is a reaction in safe conditions. This method is safer than trying the food at home, because the medical staff will be on hand and prepared to provide medication and emergency care if needed.


If your child seems to react to fish or another food, talking to a doctor or allergist is important so you can confirm whether there is an allergy. Getting a diagnosis is the first step, yet this news shows that the skin prick testing may not always be accurate. It’s worth trying the skin prick testing to see if the result is positive, but keep in mind that it’s possible for the result to be a false negative. Follow your gut and look for reactions, and if you think your child has an allergy or you notice symptoms, make sure you follow up with your doctor and provide as much information as possible.

Learn more about fish allergies and what ingredients to look for on food labels here.