What are some signs that tell you that you have a shellfish alleregy?

Stereotypical signs: Shellfish allergy is typically of the anaphylactic variety. Within seconds, minutes or an hour or two after eating even a small amount you have lip & tongue itching or swelling, difficulty breathing, cough, choking, nausea, vomiting, hives, and eyelid & facial swelling. You may have some but not all of these symptoms. Symptoms starting after 1 hour usually exclude lip, tongue & choking.