Shellfish is one kind of seafood commonly seen on our table. It includes crustaceans such as shrimp, crab and lobster, and mollusks such as clams, mussels, oysters and scallops. Shellfish is one of the major allergens. People who are allergic to shellfish may develop asthma, nose allergies, allergic dermatitis, and migraines. In severe cases, it may be more likely to cause epilepsy or anaphylactic shock. After the food is processed or cooked, it is often difficult to identify the presence of shellfish by the appearance of the food. The best way to reduce food allergies is to avoid eating foods that contain allergens. Many countries include the European Union, the United States, New Zealand, Australia and Taiwan, all have regulations about food allergen labeling.

Allergy to shellfish, including crustaceans (e.g., crabs, prawns, shrimps) and mollusks (e.g., snails, oysters, scallops, squids) will have symptoms like dizziness, troble breathing, skin reactions and asthma, if severe, allergic shock.