The causes for excessive mucus in the stool include irritable bowel syndrome and ulcerative colitis, according to About.com. Other causes for excessive mucus in the stool include anal fissures, bacterial infections, bowel obstruction or Crohn's disease.
Ulcerative colitis is a condition in which the mucus membrane of the colon becomes painful and develops small ulcers, explains About.com. The ulcers bleed and produce mucus and pus. With irritable bowel syndrome, there is an increase of mucus production in the intestines. This mucus passes into the stool and often occurs in diarrhea-predominant irritable bowel syndrome instead of other forms of the condition, though all forms of irritable bowel syndrome cause the production of small amounts of mucus.
Crohn's disease is a condition that doesn't necessarily cause mucus production, but it may cause anal fissures, which do cause excess mucus production, states About.com. Bacterial infections often cause extra mucus in the stool and can cause other symptoms such as fever, diarrhea and abdominal cramps. Sometimes this resolves on its own, but other infections may be serious and require antibiotics.
A bowel obstruction can also cause mucus in the stool, and also causes constipation, abdominal distension, vomiting and cramps, claims About.com. There are many things that may cause a bowel obstruction, including adhesions, gallstones, a hernia, tumor or swallowing an item that is not food. Typically, the treatment for a bowel obstruction is surgery.