Combined Shellfish & Finfish Screen

Testing for Allergies:

Cod, Prawn/Shrimp, Salmon, Scallop, Squid, Tuna



Allergies to finfish and shellfish are relatively rare, but can cause a range of symptoms including wheezing, coughing and dizziness, hives, facial swelling and, in severe cases, anaphylaxis.


What is a finfish or shellfish allergy?

Your body mistakenly treats fish and/or shellfish as a threat and releases antibodies that cause the reaction.

Which fish or shellfish?

It is rare to be allergic to all fish or shellfish. As proteins vary from species to species, so can the allergies – so being allergic to one type of fish or shellfish does not automatically mean you will be allergic to others.

What are the symptoms?

Range from vomiting, wheezing and coughing to facial swelling, hives and, in worst cases, anaphylaxis.

How do I know if I’ve got it?

A simple blood test is all you need. Book yours now.

Did You Know?

Although shellfish and finfish are relatively rare forms of food allergy within the UK, the reactions to them can be amongst the most severe.

What is a finfish or shellfish allergy?

Like all food allergies, a shellfish or finfish allergy is caused by your body’s immune system mistakenly reacting to the proteins within the food, and treating them as a threat. In response to that "threat" your body releases antibodies which trigger the allergic reaction.

Having a finfish allergy (by which we mean cod, salmon, tuna etc) does not mean you will necessarily be allergic to all finfish. And having a shellfish allergy does not automatically mean you will be allergic to all forms of shellfish (crustaceans like crab and lobster, but also molluscs such as squid or scallop). There is little evidence even to suggest that having an allergy to shellfish makes you more likely to have a finfish allergy (or vice versa).

The problem with seafood allergies

Finding precisely what species of fish or shellfish you are allergic to can be surprisingly complex. That’s because, perhaps more than any other food allergen, cross contamination is common among fish and shellfish. Because of the way products are handled and stored at fish markets and even in supermarkets, it’s easy for proteins to become mixed. If you suffer a reaction to a particular form of seafood, it can be difficult to know for certain whether the cause was the food itself, or some residual protein carried across from another species.

That’s why testing can be so vital – because the fish or shellfish allergy you think you have may not be the one you actually have. It’s all the more important to determine precisely what your allergy is because, although rare, allergic reactions to finfish and shellfish can be severe.

What are the symptoms of a finfish or shellfish allergy?

Whilst the proteins that trigger the reactions in seafood can be very different, the reactions themselves can be almost identical. Severity varies, but symptoms may include:

  • Wheezing and shortness of breath
  • Persistent coughing
  • Vomiting
  • A raised, red, itchy rash anywhere on the body (hives)
  • Swelling around the face, particularly the eyes, lips, tongue and roof of the mouth
  • Dizziness

In the most severe cases, finfish or shellfish allergies can trigger anaphylaxis. This combination of breathing difficulties and feeling faint is commonly called anaphylactic shock and it can be fatal if left untreated. If you suspect anaphylaxis, dial 999.


The simplest "treatment" is to avoid seafood. In cases of extreme sensitivity, even touching fish or shellfish, or simply breathing the air in a fish market, may be enough to trigger a reaction.

Because of the issues with cross contamination noted above, you may be advised to avoid all finfish or shellfish if diagnosed with an allergy.

If you are at risk of a serious allergic reaction, talk to your GP about carrying an adrenaline auto-injector, which can help reduce the severity of an anaphylactic reaction.

How do I get tested?

Better2Know’s fish allergy testing covers a wide range of finfish and shellfish including:

  • Cod
  • Prawn/Shrimp
  • Salmon
  • Scallop
  • Squid
  • Tuna

The simple blood test results in a positive or negative result, giving you reassurance about your allergy.

Contact Better2Know today on the number above to book your screen.