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Crustaceans

Crustaceans es la entrada 2 de las catorce sustancias que el anexo II del Reglamento (UE) n.º 1169/2011 hace declarables. IgE-mediated food allergy, mainly to tropomyosin. Dónde se esconde, qué exenciones aplican y con qué reacciona de forma cruzada.

Esto es información de referencia, no un diagnóstico ni un plan de tratamiento. Un calendario de polen no puede decirle a qué es alérgico, y ninguna página puede declarar un alimento seguro para usted — solo la etiqueta del paquete en la mano y el clínico que conoce su historia. Cualquier cosa más allá de síntomas leves y de corta duración en boca o nariz — hinchazón que afecta la respiración o la deglución, urticaria lejos de la boca, sibilancias, vómito o desmayo — es una pregunta de emergencia, no de lectura.

Qué dice la ley

Anexo II, entrada2: “Crustaceans and products thereof”

Esa redacción lleva toda la obligación. La sustancia debe declararse siempre que se use en la elaboración de un alimento y siga presente en el producto acabado, incluso en forma alterada, y debe destacarse en la lista de ingredientes por tipografía — negrita, mayúsculas, cursiva, subrayado o un color contrastado. No hay requisito legal de un recuadro de alérgenos aparte, así que la lista de ingredientes es donde mirar.

Source: Reglamento (UE) n.º 1169/2011, anexo II y artículo 21 · checked 2026-09-06

Qué es realmente la reacción

Crustacean allergy means prawns, shrimp, crab, lobster, langoustine and crayfish. The dominant allergen is tropomyosin, a muscle protein that is heat-stable, so cooking does not make a crustacean safe and the steam from a boiling pot can be enough to trigger symptoms in a sensitive person. Reactions tend to be immediate and can be severe.

Who gets it, and does it last

Unlike milk and egg allergy, crustacean allergy usually begins in adulthood and usually persists. It is one of the more common causes of food-triggered anaphylaxis in adults across Europe.

Where it hides

• Fish stock, bouillabaisse and seafood soups
• Surimi and crab sticks
• Thai and Vietnamese pastes and curries containing shrimp paste
• Some kimchi
• Prawn crackers
• Glucosamine supplements made from shellfish

The August crayfish party is a fixture in Sweden and Finland, and prawns run through the salads, sandwiches and party food of the whole region. Shellfish stock also turns up in restaurant sauces that are not described as seafood dishes at all, which is the situation worth asking about.

Cross-reactions

Tropomyosin is shared across the arthropods and molluscs, which produces one of the best-known cross-reaction patterns in allergy: crustaceans with molluscs, and both with house dust mite and cockroach. A house dust mite allergic adult who reacts to their first plate of prawns is following a documented route. Crucially, crustacean allergy has nothing to do with fish allergy — they are unrelated animals with unrelated proteins, and "seafood allergy" as a single idea is not a clinical category.

The labelling detail

Crustaceans are entry 2 with no exemptions, so any crustacean-derived ingredient must be declared and emphasised however small the quantity. There is no threshold below which it stops being declarable.

Exemptions: none. Entry 2 has no carve-outs at all, so there is no processed fraction of it that escapes the label.

Precautionary wording — “may contain”, “made in a factory that also handles” — is a separate matter: it is voluntary, unstandardised and carries no threshold. How strictly to treat it is a clinical decision, not a reading of the label. The labelling explainer sets out the whole frame, including what happens in restaurants and bakeries where there is no pack at all.

Qué se lee mal

Two errors matter. Being allergic to prawns does not mean being allergic to fish. And an iodine allergy — or a reaction to iodinated contrast media in a hospital scan — is not caused by shellfish; the belief that it is has been examined repeatedly and has not held up.

Fuentes:Reglamento (UE) n.º 1169/2011, anexo II· Reglamento de ejecución (UE) n.º 828/2014 de la Comisión (declaraciones de gluten)· Nomenclatura de alérgenos WHO/IUIS· ventanas de temporada de los programas nacionales de vigilancia aerobiológica de Estonia, Finlandia, Suecia, Dinamarca y Noruega· patrones de reacción cruzada parafraseados de la literatura alérgica y material de EAACI· comprobado2026-09-06

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