Causes of mucus in the stool

Updated February 21, 2017

The body often gives signs when something is wrong. If there is a problem in the digestive system, these signs can show up as changes in a person's bowel habits. Substances such as mucus might suddenly start showing up in the stool. While the cause may be benign, it can also indicate a medical problem that needs attention. It's important to know how to differentiate between normal causes of mucus in stool and causes that might mean you need to see a doctor.


Mucus is a sticky, jelly-like substance produced by various parts of the body. Often it is clear, although it can also appear to be whitish, greenish, or yellow in colour. Although mucus is most commonly associated with the respiratory system, it can also be produced by the intestines. Because of this, it sometimes shows up visibly in a person's stool.


Under normal circumstances, the intestines produce mucus to maintain moisture in the colon's lining and keep it lubricated. A small amount of this mucus can attach itself to stool, and it may be visible in the stool when it is expelled from the body.

Normal Causes

It is normal to have a small amount of mucus in the stool, since this is just a by-product of the beneficial mucus produced by the intestines. The Mayo Clinic says that it's also normal from the amount of mucus in stool to increase when you are suffering from constipation or diarrhoea or if the intestines are temporarily inflamed.

Abnormal Causes

Although mucus in stool is usually normal and harmless, the Mayo Clinic says there are times when it may be a sign of a bigger problem. It could indicate an underlying medical issue such as Crohn's disease or ulcerative colitis. Mucus in the stool may be abnormal if it occurs at the same time that your bowel habits change or if it lasts longer than a few weeks. If it is accompanied by blood in the stool or bleeding from the rectum, it may also be signalling a problem.


If you have mucus in your stool and believe that it might be a sign of a bigger problem, you should visit your doctor. He can take a history and perform an examination to see if there is a need for further tests. Then he can reassure you if the mucus is normal or give you a treatment plan if he finds an underlying medical condition.

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About the Author

Based in Kissimmee, Fla., Barb Nefer is a freelance writer with over 20 years of experience. She is a mental health counselor, finance coach and travel agency owner. Her work has appeared in such magazines as "The Writer" and "Grit" and she authored the book, "So You Want to Be a Counselor."