Why does eating shellfish make some people sick?

Many people are allergic to shellfish and can have life threatening reactions. It would be extremely important that they avoid all shellfish (shrimp, crab, lobster and crayfish). People allergic to these foods are usually not allergic to clams, mussels and abalone which are in a different family.
Discovery Health
Administration

Shellfish such as clams, oysters, mussels and scallops filter water through two shells to feed on algae, plankton and tiny life forms called flagellates. Sometimes the flagellates eat toxic alkaloids, which makes them toxic. A shellfish that eats those will accumulate toxins inside and then pass those on to whoever eats that shellfish. No amount of heat during cooking will destroy those bacteria once a shellfish becomes toxic. Whichever kind of alkaloids the flagellates consumed determines which toxins are present and which type of shellfish poisoning you'll have. Symptoms range from vomiting and diarrhea to short-term memory loss and dementia.

Continue Learning about Seafood Allergy

Seafood Allergy

Seafood Allergy

If you're allergic to fish or shellfish, you must avoid fish and food containing fish products. Some sufferers also experience symptoms if their food came into contact with the same grill where fish was cooked, the same utensils t...

hat handled fish or the same cooking oil that fried their French fries and a batch of shrimp. With a shellfish allergy, lobster, crab, oysters, clams, scallops, abalone, shrimp, sea urchin, crayfish and mussels all are problematic. With a fish allergy, regular fish, as well as foods containing fish such as Worcestershire sauce, Caesar salad and imitation seafood, are off limits.
More

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.