When I was younger, I was told I was allergic to shrimp after I had some severe reactions, and I've avoided seafood ever since. Do I still need to avoid other shellfish, such as crabs and lobster?
All shellfish are closely related, and they all include similar allergy-causing proteins called "tropomyosins." This is especially true of shellfish that are in the same family. (There are two main families of edible shellfish: crustaceans, which include shrimp, lobsters, crabs and crayfish, and mollusks, which include oysters, scallops, clams and mussels.)
There is a high probability that anyone who is allergic to one type of shellfish is allergic to most or all types of shellfish in the same family. There is also a decent probability that they are allergic to types in the other family. Don't try to taste different types of seafood to see if you can tolerate them if you've already determined that you're allergic to one kind of shellfish. Shellfish allergies tend to be severe, and they are among the most common food causes of anaphylaxis, a potentially life-threatening reaction. Food allergy testing at an allergist's office is a better way to find out if you are able to eat some kinds of seafood. You can find an allergist through your doctor or through a service, such as UCompareHealthCare.
Sources:
Adkinson, N. Franklin, et al. "Chapter 36: Allergen Structure and Function." Middleton's Allergy: Principles and Practice. 6th Ed. Philadelphia: Mosby, Inc., 2003. Zhang, Yan, Hiroaki Matsuo, and Eishin Morita. "Cross-reactivity among Shrimp, Crab and Scallops in a Patient with a Seafood Allergy." Journal of Dermatology. Mar. 2006. 33(3), 174-77(4). 27 Dec. 2008.
