Mayo Clinic Health Manager
Get free personalized health guidance for you and your family.
Get StartedCauses
By Mayo Clinic staffAll food allergies are caused by an immune system malfunction. Your immune system identifies certain shellfish proteins as harmful, triggering the production of antibodies to neutralize the shellfish protein (allergen). The next time you come in contact with proteins in shellfish, these antibodies recognize them and signal your immune system to release histamine and other chemicals that cause allergy symptoms.
Histamine and other body chemicals cause a range of allergic signs and symptoms. Histamine is partly responsible for most allergic responses, including runny nose, itchy eyes, dry throat, rashes and hives, nausea, diarrhea, difficulty breathing, and in some cases, anaphylactic shock.
There are several types of shellfish, and each kind contains different allergy-causing proteins.
Crustaceans include crabs, lobster, crayfish, shrimp and prawns.
Mollusks include:
- Bivalves, such as clams, mussels, oysters and scallops
- Gastropods, such as limpets, periwinkles, snails (escargot) and abalone
- Cephalopods, such as squid, cuttlefish and octopuses
Some people are allergic to only one type of shellfish, but can eat others. However, some people with a shellfish allergy must avoid all shellfish.
- Sicherer SH. Seafood allergies: Fish and shellfish. http://www.uptodate.com/home/index.html. Accessed April 22, 2009.
- Sampson HA. Food-induced anaphylaxis. http://www.uptodate.com/home/index.html. Accessed April 22, 2009.
- Sicherer SH. Food allergen avoidance. http://www.uptodate.com/home/index.html. Accessed April 22, 2009.
- Burks W. Clinical manifestations of food allergy. http://www.uptodate.com/home/index.html. Accessed April 22, 2009.
- Wood R. The natural history of childhood food allergy. http://www.uptodate.com/home/index.html. Accessed April 22, 2009.
- James JM, et al. Respiratory manifestations of food allergy. http://www.uptodate.com/home/index.html. Accessed April 22, 2009.
- Marcus EN. Marine toxins. http://www.uptodate.com/home/index.html. Accessed April 22, 2009.
- Burks W. History and physical examination in the patient with possible food allergy. http://www.uptodate.com/home/index.html. Accessed April 22, 2009.
- Burks W. Diagnostic tools for food allergy. http://www.uptodate.com/home/index.html. Accessed April 22, 2009.
- Seafood allergy. American Academy of Allergy, Asthma & Immunology. http://www.aaaai.org/patients/advocate/2006/winter/seafood.asp. Accessed April 22, 2009.
- Seafood allergy. Asthma and Allergy Foundation of America. http://www.aafa.org/display.cfm?id=9&sub=20&cont=518. Accessed April 22, 2009.