Irritable bowel syndrome, pathophysiology. Illustration of a digestive system suffering from irritable bowel syndrome (IBS). IBS is also known as spastic colon or irritable colon syndrome. It causes abdominal pain and cramps, and irregular bowel habits such as constipation and diarrhoea. The condition is thought to be linked to anxiety and stress, which disturb involuntary muscle movement in the intestines. There is no cure, but laxatives, anti-diarrhoeal and anti-spasmodic drugs may help to alleviate the symptoms. Increasing the intake of fibre and water in the diet, and decreasing stress is also recommended.