Unlike other food allergies, which are typically first observed in babies and young children, an allergy to fish may not become apparent until adulthood; in one study, as many as 40 percent of people reporting a fish allergy had no problems with fish until they were adults.
Having an allergy to a finned fish (such as tuna, halibut or salmon) does not mean that you are also allergic to shellfish (shrimp, crab and lobster). While some allergists recommend that individuals with a fish allergy avoid eating all fish, it may be possible for someone allergic to one type of fish to safely eat other kinds. If you are allergic to a specific type of fish, your allergist can help you determine whether other varieties may be safe to eat.
Fish Allergy Symptoms
- Hives or a skin rash
- Nausea, stomach cramps, indigestion, vomiting and/or diarrhea
- Stuffy or runny nose and/or sneezing
- Anaphylaxis (less common), a potentially life-threatening reaction that impairs breathing and can cause the body to go into shock
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Fish Allergy Management and Treatment
- Avoid fish and fish products.
- Read food labels carefully.
- Treat symptoms of anaphylaxis with epinephrine (adrenaline).
For more information on fish allergy management and treatment click here.
Fish Allergy Symptoms
As with other food allergies, the symptoms of a fish allergy may range from mild to severe. They include:
Diagnosing Fish Allergies
Your allergist may diagnose an allergy to a specific kind of fish through a skin-prick test or a blood test.
In the skin-prick test, a small amount of a liquid containing protein from the fish being tested is placed on the back or forearm, which is then pricked with a small, sterile probe to allow the liquid to seep into the skin. If a raised, reddish spot forms within 15 to 20 minutes, that can indicate an allergy.
In the blood test, a blood sample is sent to a laboratory to test for the presence of immunoglobulin E antibodies to protein from the fish being tested.
If these tests aren’t definitive, your allergist may order an oral food challenge. Under medical supervision, you’ll eat small amounts of fish or a fish product to see if a reaction develops. Because of the possibility that a reaction could be severe, this test is conducted in your allergist’s office or at a food challenge center with emergency equipment and medication on hand.
Fish Allergy Management and Treatment
Managing a fish allergy includes strict avoidance of the fish to which you are allergic. Doctors typically advise people who are allergic to one type of finned fish to avoid all types. If you are allergic to a specific fish and would really like to have other varieties of fish in your diet, speak to your allergist about testing for those varieties. Do not change your diet without guidance from your allergist.
Fish is one of eight allergens with specific labeling requirements under the Food Allergen Labeling and Consumer Protection Act of 2004. Under that law, manufacturers of packaged food products sold in the U.S. and containing fish or a fish product as an ingredient must identify on the ingredient label, in clear language, the specific type of fish used.
Many prepared foods contain fish in some form. Fish is a common ingredient in Worcestershire sauce and Caesar salad and is sometimes found in imitation crab products in the form of surimi, a processed food made mainly from Alaska pollock. Fish is also prevalent in Asian cuisine, which uses fish-based stock for many dishes.
While an allergy to fish protein is most common, it is possible to be allergic to fish gelatin (made from fish skin and bones). People with a fish allergy should consult their allergist before taking fish oil dietary supplements.
If your allergist gives you the go-ahead to eat certain types of fish, take extra precautions to avoid eating fish that has come in contact with the type of fish that causes your allergic reaction. Be advised that some restaurants may substitute cheaper types of fish for what is on the menu (for example, what is listed as red snapper could really be tilapia). Since many types of fish look alike once they are filleted, dishonest suppliers to supermarkets may substitute cheap fish for more expensive types, according to an investigation by Oceana, a conservation nonprofit.
To avoid either cross-contact or the possibility of eating a mislabeled fish, be sure to tell whoever handles the fish you plan to eat about your allergy. Ask whether there is a risk that you will eat something that triggers your allergy.
Due to the high risk for cross-contact during food preparation, it is best to avoid seafood restaurants in general, even if you plan to order something other than fish. Stay out of areas where fish is being cooked, as proteins may be released into the air during cooking.
People with a fish allergy do not necessarily have to avoid shellfish (and vice versa); there appears to be no relationship between fish and shellfish allergies. However, an individual can be allergic to both fish and shellfish, just as someone can be allergic to both eggs and peanuts.
Treatment for fish allergy includes strict avoidance of the fish to which you are allergic. Because fish is often implicated in cases of food-induced anaphylaxis, allergists advise fish-allergic patients to treat symptoms of a reaction with epinephrine (adrenaline), which is prescribed by your doctor and administered in an auto-injector. Anaphylaxis can come on quickly and can be fatal unless epinephrine is injected as soon as you notice symptoms developing. Be sure to call for an ambulance, and alert the dispatcher that epinephrine has been used and more may be needed.
Only epinephrine can reverse the symptoms of anaphylaxis; for less severe symptoms, you may find that antihistamines are helpful.