I personally do not believe one has anything to do with the other. I believe I have a very strong immune system. I get a cold for a few days maybe once every three years, and I haven't had the flu in about thirteen years (which was the only time I can recall ever having been ill more than two or three days). Maybe I just don't expose myself, or perhaps I am just lucky. Everyone's body has different responses and reactions however.Anyway, I would think the fact that IBS is categorized as functional is enough to show that there has been no observable link between IBS and the immune system. I am no expert, but I don't even see how the two could be related. The only advice I can offer is to talk your doctor.