Irritable Bowel Symptoms - Version 1.0 Irritable bowel symptoms, free ebook. Most individuals are surprised to learn they are not alone with symptoms of IBS. In fact, irritable bowel syndrome (IBS) affects approximately 10-20% of the general population. IBS is a very serious disorder in the digestive system and leads to symptoms such as cramping, abdominal pain, flatulence, bloating, and changes in bowel habits.