Irritable bowel syndrome (IBS) is a common gastrointestinal disorder that affects both the small and large intestines. Symptoms of IBS include abdominal cramping, bloating, and changes in bowel habits. It is considered a disorder of how your gut and brain work together. IBS does not cause permanent harm to the digestive tract or increase the risk of colorectal cancer. However, it can significantly affect a person's quality of life.