Shellfish is the most common food allergy for adults in the United States. Almost 7 million people, or just over 2 percent of all Americans share this allergic reaction. Of those, approximately 60 percent develop their allergy to shellfish after they become adults.
Food allergy basics
A food allergy is a reaction by the body’s immune system. Normally, the body treats food as something that is beneficial. But when someone is allergic to a food, the body sees that allergen as a threat, like a bacteria or virus. This triggers the immune system to release antibodies to fight off the threatening particles. Depending on how severe the allergy is, food allergy symptoms can include hives, swelling around the mouth, itchy skin, runny nose, and stomach problems including nausea and diarrhea. The most serious allergic reaction is anaphylaxis, which is a full body reaction that can make the tongue and airway swell and cause a sudden drop in blood pressure. Anaphylaxis makes it hard to breathe and can result in death.
Shellfish allergy basics
Shellfish allergies include mollusks such as clams, mussels, and oysters as well as crustaceans which include shrimp, lobster, and crabs. Octopus and squid are also included in shellfish allergy.
For purposes of food allergy designations, fish are considered to be creatures with fins. Although fish and shellfish are separate allergies, many people who are allergic to shellfish are also allergic to fish. Allergic reactions to shellfish most commonly result in hives, redness and swelling under the skin, and anaphylaxis or swelling in the airways.
Foods to avoid
The most common cause of shellfish allergy is shrimp. But it is important to note that if you are allergic to any type of shellfish, there is a good chance you will be allergic to other shellfish as well as fish. The protein found in shellfish that most often causes allergies is also found in dust mites and cockroaches, so you may also be allergic to these insects.