It's not known why some people react to particular proteins and others do not. Researchers are beginning to analyze the chemistry of these proteins, Bielory says, but most of the allergens are not yet well-defined. The only way to safely handle the problem is to abstain. For those who yearn for a Maine lobster claw dipped in butter, but have had an allergic reaction in the past, Bielory says taking an antihistamine before indulging will not work. He advises those who have had extreme reactions in the past to carry an epinephrine injector system in case they inadvertently eat something that contains shellfish protein, such as fish stock, which may be used as a base in soups.
Skin tests are more sensitive, especially in patients with a history of a systemic reaction.
For those whose reactions have been severe, it's particularly important to remember to read packaged food labels for seafood flavorings or unexpected sources of the allergen. You should also remember that any dish prepared in a seafood restaurant may be cross-contaminated with shellfish during handling or cooking.