What is a spastic colon? Spastic colon is another term for irritable bowel syndrome (IBS), a common condition with symptoms including cramping, constipation or diarrhea, bloating, and abdominal pain. The term ‘spastic colon’ comes from the idea that muscle spasms in the large intestine were to blame for abdominal pain and changes in bowel habits. However, IBS is now known to be influenced by more factors beyond muscle spasms, and the term ‘IBS’ is used to cover a wider range of gastrointestinal symptoms. If you have a spastic colon, learning some basic information about IBS may help you to find appropriate treatment.