I know this is ironic, but I suffer from lots of nausea, but I rarely puke. I've never thrown up from my Crohn's, but I have from the stomach flu. I hate it so much, that I really have to be sick before I do it. My brother who also has CD doesn't get near as much nausea, but he throws-up more often than I do. I think he just wants to get rid of the feeling and quick. Ugh! I can't do that.
