Mucus in diarrhea can be caused by a variety of conditions, including ulcerative colitis (UC), infections of the intestinal tract, or irritable bowel syndrome(IBS). Although uncommon, a bowel obstruction may also result in excess mucus in the stools. Only a physician can make a firm diagnosis, so it is important for sufferers to report any unusual symptoms to a health care professional.

The large intestines normally make mucus in order to help stools pass more smoothly. This substance is generally the consistency of jelly and can be brown, clear, or yellow in color. Bloody mucus or mucus with pus is not considered normal, and should be investigated further to rule out any serious health problems. Most conditions that affect the colon are not life-threatening, but they can cause considerable discomfort if left untreated.

One common cause of mucus in diarrhea is UC. The mucus results from inflammation in the colon which can lead to an ulcer. Excess mucus is often produced, and the ulcer can sometimes rupture and leak pus or blood from the rectum along with the passing of stools. This can be a serious condition, primarily if blood is visible, and should be investigated by a doctor as soon as possible.

Inflammation can also occur due to an infection of the intestines. This is most commonly caused by eating foods that are not cooked thoroughly. Diarrhea and mucus overproduction generally both subside once the immune system takes care of the underlying infection.

Irritable bowel syndrome is a chronic condition which often causes diarrhea, constipation, gas, bloating, and stomach pain. Mucus in diarrhea is also common. There are treatments available to treat this problem. Along with dietary changes and exercise, IBS symptoms can often be alleviated entirely for long periods.

Any visible mucus, whether accompanied by diarrhea or not, should be looked into by a doctor. In some rare cases a bowel obstruction may be to blame. Even more rarely the obstruction is the result of colon or colorectal cancers. Although unlikely, this is a serious condition that is potentially life-threatening. Treatment is needed as soon as possible if cancer is suspected.