Shellfish Allergy

There are two types of shellfish: crustaceans (e.g., shrimp, crab, and lobster) and mollusks (e.g., clams, mussels, oysters, and scallops). Most shellfish reactions are caused by crustacea, and the reactions are often severe. People allergic to one group of shellfish are not always allergic to both types, but allergists usually recommend avoiding all varieties. Also, a shellfish allergy is different from a finned fish allergy, and an allergy to one does not imply an allergy to the other.

Various types of shellfish on a plate.

Always read ingredient labels to see if products contain shellfish or were processed with equipment also used for shellfish. If you are allergic, you may need to avoid seafood restaurants due to a high risk of cross-contamination.

Crustaceans to Avoid

  • Barnacle
  • Crab
  • Crawfish/Crawdad
  • Krill,
  • Lobster
  • Prawns
  • Shrimp 

Mollusks to Avoid:

  • Abalone
  • Clams
  • Cockle
  • Cuttlefish
  • Limpet, Mussels
  • Octopus
  • Oysters
  • Periwinkle
  • Scallops, Snails (escargot)
  • Squid (calamari)
  • Whelk (turban snail)

Although not technically mollusks, it may also be advisable to avoid sea cucumbers and sea urchins.

Other Possible Sources of Shellfish

  • Bouillabaisse
  • Cuttlefish Ink
  • Glucosamine, Fish stock
  • Seafood flavoring
  • Surimi

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Did You Know?

  • About 60% of shellfish allergies have been found to begin in adulthood.
  • People do not typically outgrow shellfish allergies.