Fishing for Answers: Seafood Allergies Impact Few, But Can Be Deadly if Undiagnosed

Americans are eating more fish and seafood than ever. Seafood, a high-protein, low-fat food, offers many choices for grilling, frying, baking and fresh food dining. Unfortunately, for a percentage of people, different types of fish and shellfish, no matter how it's cooked, can trigger dangerous allergic reactions.

"Fish and shellfish are among the most common foods that trigger severe allergic reactions," says Dan Atkins, MD, a National Jewish physician who treats people with food allergies.

For someone with extreme sensitivity, anaphylaxis may occur, resulting in a sudden drop in blood pressure and swelling of the bronchial tissues, causing severe breathing difficulty. These reactions can arise in seconds and can be deadly. Severe anaphylactic shock is fatal if not treated immediately.

General allergic symptoms—occurring within a few minutes to a few hours of eating shellfish—include tingling and swelling in the mouth and throat; runny nose, sneezing, nausea, vomiting, diarrhea, swelling, hives and difficulty breathing.

"If someone has a life-threatening reaction to one crustacean, such as shrimp, testing will usually show that other crustaceans—crab, lobster and crayfish—will also cause a reaction," Dr. Atkins says. "This relationship is known as cross-reactivity."

Raw or cooked, fish can still cause allergies. "For most sufferers it doesn’t matter how fish is prepared," he says, "since the allergenic proteins in cod, shrimp, lobster or any other fish that causes allergic reactions are not destroyed by cooking."

Minimal exposure to seafood can cause symptoms for some people. "Handling fish, or inhaling fish vapors while walking through a fish market or in a restaurant can cause a reaction in extremely sensitive individuals," Dr. Atkins says. Exposure can occur by eating another food cooked on the same surface as fish or absorbing fish protein through a cut.

The good news about food allergies is that only 1 to 2 percent of adults has a true food allergy of any kind. If you suspect you’re among this group, meet with your personal physician and, if necessary, devise a treatment plan. Precautions can be taken to avoid triggering a reaction: avoid contact with the food, inform those around you about your food allergy and wear a medical alert bracelet. Have a plan for treatment of reactions. Know the medicines used to treat reactions and carry them at all times.

"Food allergies may be misdiagnosed without a careful patient history and an appropriate evaluation," Dr. Atkins notes. "If you had just eaten shrimp before a reaction, the assumption might be made that shrimp is the cause of the reaction. It may be, but other potential causes such as another food or ingredients in sauces eaten at the same time need to be considered. Testing is necessary to determine the source of the problem.