As a young adult I ate Lobster for the first time. I swelled horribly the next day. I went to military clinic and was told I had a reaction to the Lobster, given injection and sent home. The Dr. told me to try a small bit of shell fish once a month, increasing it a little at a time. If I swelled as bad as before then don't eat shellfish. I did that and the swelling decreased each time I ate it. I now can eat all I want and no reaction. I didn't get sick, just swollen.