These two allergies may seem similar, but they aren’t exactly the same. Some people are allergic to both fish (like tuna, cod or salmon) and shellfish (like lobster or clams), but more often a person is allergic to only one and can safely eat the other.
SHELLFISH ALLERGY. There are two groups of shellfish: crustaceans (such as crab, lobster, and shrimp) and mollusks (such as clams, oysters, scallops, and mussels). A severe response to crustaceans is more common than a severe response to the mollusks. Those who are allergic to one shellfish are almost always allergic to all.
People who suffer from shellfish allergies are the ones who need to be the most careful. Even a small bite may result in a severe reaction, leading to anaphylaxis. Unlike milk or eggs allergies, it often develops in adulthood and is a lifelong condition for almost all sufferers.
FISH ALLERGY. While less common than a shellfish allergy, a fish allergy is a reaction to a finned fish such as codfish, tuna, halibut, flounder, tilapia, or salmon. The allergy is more common in areas where fish is a staple of a local diet.
Symptoms may not only be triggered by eating fish but also by touching and smelling. Only a specialist can help to determine what specific types of fish a person is allergic to and advise on potentially non-allergenic types.
SYMPTOMS. Reactions to seafood differ. Sometimes the same person can have a different reaction at different times. Some common symptoms include skin rashes, hives, itching, eczema, wheezing, congestion, abdominal pain, vomiting, diarrhea, itchy, watery, or swollen eyes, and tingling in the mouth.
HIDDEN SOURCES. Fish and shellfish are rarely hidden on the labels; however, there are a few surprising places where fish and shellfish can be found: Ceaser salad dressing, Worcestershire sauce, imitation crab, meatloaf, fish stock, Bouillabaisse, and seafood flavoring. Fish gelatin is often used in pepperoni and hot dogs.
Allergy testing (a skin-prick test or a blood test) is the only sure way to tell if you are allergic to fish or shellfish.