Have you ever known someone who was on a date at a nice seafood restaurant that ordered something like lobster, crab, or shrimp, and then had to be rushed to the hospital? Chances are strong that it wasn't someone trying to skip out on the bill, but a person that has an allergy to shellfish.
There is such a thing as a seafood allergy, but a shellfish one is more specific to sea creatures that have a shell of some kind, i.e. lobster, crab, shrimp, oysters, clams, and even octopus and squid. The reaction is most common when a person ingests shellfish, but can also occur if someone is exposed to steam coming off cooked or cooking shellfish. A person could also have a reaction simply by handling shellfish, like during preparation.
Severe reactions are common with shellfish. People with a severe reaction could go into anaphylactic shock causing their throat to swell and possibly make it very difficult or impossible to breath. If a person does not have a shot of epinephrine on hand a trip to the local emergency room is mandatory.
Some of the more common and less severe reactions include different parts of the body swelling up (i.e. lips, face, tongue, etc.) wheezing, nasal congestion, breaking out in a rash, itching, stomach pain, gastrointestinal distress, dizziness, and/or a tingling sensation in the mouth.
Anyone can have a shellfish allergy, but they are more common in adults than in children. For adults, a shellfish allergy is more common in women than men, but in children it is found more in boys than in girls. Those with other allergies are more likely to have one to shellfish than someone who has no allergies at all.
A family history of allergies in the family can be a good indicator. Sometimes a reaction that can be perceived as an allergic reaction to shellfish is actually a food poisoning or some kind of bacterial/viral infection. Blood or skin test need to be conducted to prove the existence of a shellfish allergy.
Like with most food allergies, avoidance is the best way to treat it. Antihistamines can help if a person has a mild reaction, but epinephrine is necessary for severe reactions.