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Oyster allergy


Information provided in co-operation with the Informall project.

Oysters are eaten either raw or cooked. They can be used as ingredients in soups and sauces, such as Chinese oyster sauce. Their scientific name is Crassostrea gigas.

Oyster allergy

Allergy to shellfish such as oyster is less well known than allergy to crustaceans. As with most food allergies, symptoms are usually mild such as oral allergy syndrome, but severe symptoms such as anaphylactic shock can also occur after consumption. Note that oysters are not currently listed in annex IIIa of the EU directive on labelling of foods and thus individuals allergic to molluscs must be alert to the possibility of oyster or other molluscs as hidden allergens.

Since oysters are bivalve molluscs, allergy to oyster is most commonly associated with allergy to other bivalves such as clams, mussels, and scallops. Reaction is also likely after ingestion of more distantly related molluscs such as limpet, snails, winkles and whelks (gastropods) or cuttlefish, octopus and squid (cephalopods). Thus, after a diagnosis of allergy to one mollusc, patients are normally advised to avoid all molluscs. Whilst most individuals with allergy to shrimps (crustacea) can tolerate molluscs, individuals with allergy to both types of shellfish have been reported. However, individuals allergic to finfish (such as cod or salmon) do not generally have allergies to shellfish.

The main allergenic protein in oyster is tropomyosin.

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