Irritable bowel syndrome (IBS) is a common disorder of the intestines that leads to crampy pain, gassiness, bloating and changes in bowel habits. Some people with IBS have constipation (difficult or infrequent bowel movements), others have diarrhea (frequent loose stools, often with an urgent need to move the bowels) and some people experience both. Approximately 35 million Americans are impacted by IBS.