In IBS patients, this system goes awry and is unable to function normally in the excretion of fecal material. The colon is responsible for absorbing water from food that enters from the small intestine. Once the colon has had the chance to absorb enough water, nerves and hormones stimulate the muscles of the colon to contract. The contractions push fecal matter toward the rectum, which holds the feces until further muscle contractions excrete the material. In IBS patients, this process is disrupted, resulting in diarrhea or constipation.
Some patients experience both.
However, the disorder is not life-threatening and does not damage the intestines. IBS does not lead to more serious diseases such as cancer. For some patients, IBS is merely a slight inconvenience. But for others, the disorder disables them from participating in normal activities and travel. Some people may be more susceptible to developing IBS if their bowels react more strongly to stimulation, stress, diet or activity.