Nearly 60% of shellfish allergy sufferers are adults. It is an allergy that often doesn’t manifest until adulthood, too.
Shellfish can cause dangerous anaphylactic reactions to highly sensitive people.
Like some of the other top allergens, those with severe immediate reactions to shellfish are often required to carry an EpiPen in case of an accidental exposure.
There are two classes of shellfish that cause allergies: mollusks and crustaceans. Clams, mussels, and oysters are examples of mollusks and shrimp, lobster and crabs are examples of crustaceans. These two groups are not biologically related but people that have an allergic reaction to one generally have a reaction to the other kind too. So, many people who are allergic to any shellfish are advised to avoid all shellfish. The protein that experts believe causes shellfish allergies is called tropomyosin. It is also present in dust mites and cockroaches. Jewish kosher law forbids the eating of shellfish. Allergy sufferers may be able to find suitable products free from cross-contamination from kosher manufacturers.
Asian sauces (ask restaurant staff, if in store, check labels).
Fruits de mer
Sliced fish soup
Surimi is a processed fish product that is a main ingredient in imitation crab or shrimp products. It is made from white fish (usually pollock or hake, but can be cod, swordfish, tilapia, even shark). Surimi may or may not contain shellfish. Call the manufacturer with your concerns before consuming surimi. Surimi is produced in many countries and processing practices vary. Processing equipment that also processes shellfish on the same lines will be cross contaminated.
Shellfish protein can be released in cooking steam so those with shellfish allergies should not be exposed to boiling shellfish.
It is also advisable to avoid all kinds of shellfish once you have reacted to one kind. The chances of reacting to another kind of shellfish are very high.
Glucosamine, a dietary supplement, is usually made from the shells of crustaceans. The proteins that cause shellfish allergies are not found in the shells. Recent studies have shown that glucosamine is safe for people with shellfish allergies, but if you are concerned, buy vegetarian glucosamine.
Omega-3 supplements are generally made from seafood. The most common source is cod liver oil, but check ingredients on the label before you take them.
Do not eat at a seafood restaurant if you have a fish or shellfish allergy. Ordering non-seafood items in a seafood restaurant is dangerous due to cross-contamination.
According to the Mayo Clinic, octopus and squid are also considered shellfish and should be avoided.
Crawfish (Crayfish or Crawdads)