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Allergic reactions to various shellfish, crustacean (shrimp, crabs, lobster, and craw fish) and mollusk (clams, oysters, scallops) are common. A shellfish allergic person must be very careful about all types of shellfish. Most of the time shellfish are not "hidden" in foods, but occasionally different shellfish may be included in Asian dishes unbeknownst to a waiter in a restaurant.

Mollusks and Crustaceans

Unless instructed otherwise by an allergist, people with shellfish allergies should avoid both mollusks and crustaceans because most shellfish allergies are caused by similar proteins. Some patients, though, can be determined through testing not to be allergic to one family and may eat that family safely.

People who are allergic to mollusks should avoid:

  • Clams
  • Oysters
  • Mussels
  • Abalone
  • Scallops
  • Cockles
  • Quahogs
  • Squid (Calamari)
  • Octopus
  • Whelks
  • Snails (Escargot)
  • Limpets

People who are allergic to crustaceans should avoid:

  • Shrimp
  • Lobster
  • Crawfish (Crayfish or Crawdads)
  • Prawns
  • Crab
  • Langoustines
  • Sea Urchin

Contact Information

Allergy and Inflammation - Research
Department of Medicine
Beth Israel Deaconess Medical Center
Center for Life Science, 9th floor
330 Brookline Avenue
Boston, MA 02215