Overview

Shellfish allergy is an abnormal response by the body's immune system to proteins in certain marine animals. Marine animals in the shellfish category include crustaceans and mollusks, such as shrimp, crab, lobster, squid, oysters, scallops and others.

Some people with shellfish allergy react to all shellfish; others react to only certain kinds. Reactions range from mild symptoms — such as hives or a stuffy nose — to severe and even life-threatening.

If you think you have a shellfish allergy, talk to your doctor. Tests can help confirm the allergy so you can take steps to avoid future reactions.