Irritable bowel syndrome (IBS) or spastic colon is a symptom-based diagnosis. It is characterized by chronic abdominal pain, discomfort, bloating, and alteration of bowel habits. Diarrhea or constipation may predominate, or they may alternate.
As a functional gastrointestinal disorder (FGID), IBS has no known organic cause. Onset of IBS is more likely to occur after an infection (postinfectious IBS-PI), or a stressful life event,but varies little with age. The most common theory is that IBS is a disorder of the interaction between the brain and the gastrointestinal tract.
