there is no evidence that irritable bowel syndrome (ibs) is a forerunner of inflammatory bowel disease (crohn's disease and ulcerative colitis together referred to as ibd). having said that there are interesting observations that suggest that some of the factors causing ibs and ibd may be similar involving the intestinal immune system and bacteria within the intestine. the great differences between ibs and ibd makes it unlikely that they are caused by identical processes. it is more likely that the manifestations they share -- for example abdominal pain and diarrhea -- are a function of the ability of the intestine to respond to disease-causing processes no matter how different in a limited number of ways.
does ibs lead to crohn's disease or ulcerative colitis?