Shrimp and shellfish allergy
Hives after a prawn curry, or a tight throat after paella? Shrimp is one of the most common food allergens in adults, and reactions often start in adulthood rather than childhood. Our test checks for IgE antibodies to shrimp and prawn, through ten shellfish markers, as part of 300 allergens and allergen components including house dust mite.
- Group
- Food
- Also known as
- prawn, shellfish, crustacean, tropomyosin, Pen m 1
Where you meet it
- Shrimp, prawns and langoustines, fresh or frozen
- Paella, curries, stir-fries, sushi and dim sum
- Fish sauce, shrimp paste, prawn crackers and some stock cubes
- Seafood mixes and surimi products
- Steam and cooking fumes where shellfish is boiled
Tropomyosin: the protein behind most shrimp results
The main shrimp allergen is tropomyosin, a muscle protein that survives cooking. Crustaceans such as shrimp, crab and lobster have very similar tropomyosin, which is why people sensitised to one are often sensitised to others.
House dust mites and cockroaches also have a tropomyosin that looks similar. Some people show shrimp IgE because of mite sensitisation, and some react to shellfish for that reason. A doctor can tell the two apart using your history and component results.
What people commonly report
Reactions people describe after shellfish include itching in the mouth, hives, swollen lips or face, vomiting, stomach cramps and wheezing. They usually start within minutes to two hours. Some people react to the steam from cooking shellfish.
Shellfish reactions can be strong. Swelling of the lips, tongue or throat, trouble breathing or feeling faint is an emergency. Call 112 (EU) or your local emergency number. Do not wait for a test.
Shellfish is not fish
Shrimp is a crustacean. Fish such as cod belong to a different group with different main allergens. Sensitisation to one does not imply the other, although some people have both. Molluscs, such as mussels, squid and oysters, also contain tropomyosin, but the overlap with crustaceans is less consistent.
A common myth links shellfish allergy to iodine or contrast dye. The allergen is a protein, not iodine. If you are worried about contrast for a scan, tell the doctor doing it.
How our test checks shrimp
The lab measures IgE to whole shrimp extracts and to single shrimp and prawn proteins, including tropomyosin. Crab, lobster, clam and squid extracts are on the same panel. Your lab report gives each a measured value and class, from Negative to Very high, on the same report as your house dust mite and cockroach results. That shows sensitisation, not a clinical allergy. Do not decide what to eat based on the result alone; talk it through with a doctor.
- Black tiger prawn: Pen m 1 (tropomyosin), Pen m 2 (arginine kinase), Pen m 3 (myosin light chain), Pen m 4 (sarcoplasmic calcium-binding protein)
- Giant freshwater prawn: Mac r 1 (tropomyosin) and Mac r 2 (arginine kinase)
- North Sea shrimp: Cra c 6 (troponin C)
- Whiteleg shrimp: Lit v 7
- Whole extracts: white shrimp and northern prawn
Known cross-reactions
- Crab, lobster and crayfish
- Crustaceans share very similar tropomyosin. Sensitisation to several crustaceans at once is common.
- House dust mite
- Mite tropomyosin resembles shrimp tropomyosin. Mite sensitisation can show up as shrimp IgE, with or without reactions to eating shrimp.
- Molluscs
- Squid, mussels and oysters also contain tropomyosin. The overlap with shrimp is real but less predictable.
Sources
- EAACI Molecular Allergology User's Guide 2.0. Pediatric Allergy and Immunology, 2023.
- Seafood allergy: A comprehensive review of fish and shellfish allergens. Molecular Immunology, 2018.
- Shellfish and House Dust Mite Allergies: Is the Link Tropomyosin?. Allergy, Asthma & Immunology Research, 2016.
Page last updated
300 allergens. One test.
A finger-prick sample at home, sent by post. A detailed lab report typically 5 days after the lab receives your sample, and our plain-English guide to reading it. €300, €1 per allergen.
Questions
If my result shows shrimp, will crab and lobster show too?
Often, because crustaceans share very similar tropomyosin. Crab and lobster are on the panel, and your results show each one separately. A doctor can tell you what the pattern means for you.
Why would house dust mite affect my shrimp result?
Mites have a tropomyosin that looks like shrimp tropomyosin, so antibodies can recognise both. That is a lab association, not proof you will react to shrimp.
Is shellfish allergy the same as an iodine allergy?
No. Shellfish reactions are to proteins such as tropomyosin, not to iodine. If you are worried about contrast for a scan, tell the doctor doing it.
Can shellfish sensitisation start in adulthood?
Yes. Shellfish is one of the food allergens most often first reported by adults. If you have had a reaction, see a doctor rather than relying on a test alone.