Fish & Shellfish Allergy

Being allergic to fish and or shellfish can be a little more tricky to live with compared to other food allergies. This type of allergy can become apparent in childhood or develop in later life. Unfortunately, for those diagnosed in childhood with a seafood allergy, it is likely to be a serious lifelong threat. It can be limited to one type of fish or shellfish or it can apply to several different types at the same time. Some people may find that while they are allergic to salmon, they can quite safely eat cod. The same rule goes for shellfish. An allergy to prawns does not necessarily mean an allergy to clams.

Seafood allergies are fairly easy to diagnose with a skin prick test. While the test is often run as a combination test whereby most shellfish can be tested for at the same time, it is sometimes necessary to run individual skin prick tests if a particular shellfish allergy is suspected. The test is the same for fish, although certain combinations of the more commonly eaten fish are run initially to eliminate them as suspects. As with the shellfish tests, testing for fish allergies can be done with individual fish proteins.


Great care must be taken when dining out. Oil that is used to fry fish or prawns may well be the same oil used to fry poultry or chips. In some restaurants raw seafood might be prepared on the same surface as other raw ingredients. Don’t be afraid to let the restaurant owner know that you have an allergy to seafood. If it cannot be guaranteed that cross contaminated of raw foodstuffs will not occur, do not eat there.

There are some individuals allergic to fresh seafood that are able to safely eat fish or shellfish that has gone through the canning process. The process would appear to disrupt the offending seafood protein in such a way that the immune system no longer finds it a threat and an allergic response is not set off. A good example of this would be canned tuna or canned prawns.

For some people, eating fish that has gone off or is beyond its best by date can cause an immune response very similar to that of an allergic response to seafood. The reaction is caused by the build up of histamines in the spoiled fish. Symptoms are respiratory difficulties, rash and swelling. If this occurs after the first time you eat seafood it is most likely an allergy and you should see your GP. If you have eaten it before without any trouble, you may want to consider the idea that what you ate was not fresh enough.

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Guide to Food Allergies