The Causes of Mucus in the Stool

Are you finding mucus in the stool? You may have a gastrointestinal infection or some other medical condition. Continue reading to learn about its most common causes and symptoms.
The Causes of Mucus in the Stool
Grecia Morillo

Written and verified by the doctor Grecia Morillo.

Last update: 26 September, 2022

The digestive system has several membranes throughout the intestines and these are responsible for secreting mucus in the stool to completely lubricate the digestive tract, which allows food to pass through easily, as confirmed in this study by the University of Costa Rica.

With normal amounts of mucus, the stomach is able to function properly and the body can constantly absorb nutrients and eliminate waste through stool.However, all of those processes change when mucus levels are higher than normal. Furthermore, this may take place due to an infection or other ailment, which in turn indicates something isn’t right in your digestive system.

Possible causes of excessive mucus in the stool

  • Amoebic dysentery, as shown in this study carried out by the University of Zulia in Venezuela.
  • Ulcerative colitis, as suggested in this study carried out by the Ramón y Caja University Hospital Clinic in Madrid.
  • Colon polyps, as confirmed in this study by the American Society of Colon and Rectal Surgeons.
  • Diverticulitis, as stated in this investigation, also by the Ramón y Cajal University Hospital, Madrid.

You might also be interested in reading: 5 Digestive Disorders that Can Cause Weight Gain

Learn more about the diseases that cause mucus in stool

1. Ulcerative colitis

A person with colitis.

Ulcerative colitis is an inflammatory condition that affects many people worldwide. Moreover, it manifests as a bad inflammation in the entire mucus membrane of the colon to the point of ulcers. The most frequently affected portion is the large intestine and anus.

This is due to an irritation in the intestines, which lack protection from acids. This doesn’t only cause general discomfort, but can also lead to also to specific symptoms such as large amounts of mucus in stool. Other symptoms are:

  • Diarrhea, sometimes with blood and pus
  • Weight loss
  • Pain in the rectum and abdomen
  • Weight loss
  • Fever
  • Fatigue

2. Bacterial infections

The presence of many kinds of bacteria in the colon and in different parts of the intestine is normal. These bacteria are helpful for digestion.

However, when the bacterial balance gets out of controlit can lead to the appearance of infections, causing not just diarrhea, but also symptoms such as mucus in the stool, or in some cases, blood streaks, which require immediate medical attention.

In turn, the action of some parasites such as Entamoeba histolytica and Giardia lamblia may be responsible for the appearance of mucus in the stool. In fact, a study conducted by La Salle University in Mexico showed that these parasites exert an irritative effect on the intestine, which increases mucus production.

Viruses can also lead to the presence of mucus in the stool, especially in young children. Furthermore, the most frequent etiologic agent of this type of infections in children is rotavirus, which can lead to the expulsion of mucus in up to 27 percent of the cases according to research.

3. Intestinal obstruction

A person with stool obstruction.

If you don’t drink sufficient amounts of water, over time your body may fail to regularly secrete gastric hormones and fungal infections.

The consequences are frequent episodes of constipation that eventually obstruct the digestive tract due to the constant mucus production in stools. Many of these cases require surgical intervention.

This study, lead by the Alamedilla Health Center in Salamanca, also suggests that mucus in stool could be an early warning side for the appearance of other health issues, such as Crohn’s disease. Moreover, symptoms suggestive of intestinal obstruction include the following:

  • Sudden absence of stool
  • A constant urge to defecate
  • Abdominal distention
  • Vomiting
  • Gas
  • Swelling of the belly

4. Diverticulitis

A person with diverticulitis.

Inside the colon there are small anatomical pockets known as diverticula, which appear due to a structural weakness. When inflamed, they cause an irritative condition called diverticulitis, which eventually leads to the appearance of mucus in the stool as well as other symptoms like abdominal pain and blood in the stool.

5. Colon polyps 

When polyps are present in any area of the colon, the irritation they cause simultaneously injures the mucus-secreting membranes causing them to be excreted directly with the stool and, in turn, signals that a consequential colonic cyst may be present behind the mucus.

Unfortunately, polyps in the colon usually cause very unspecific symptoms, which makes their diagnosis difficult. Among the main clinical manifestations are the following:

  • Rectal bleeding
  • Changes in the general appearance of the stool
  • Periods of diarrhea or constipation
  • Abdominal pain

Read the following article: 12 Symptoms of a Damaged Gut Flora

6. Crohn’s disease

Mucus in the stool.

Due to it being a chronic illness, having Crohn’s means that you will always experience symptoms because it has an immunological origin. While you can treat some of the clinical symptoms, there is no definitive cure.

Furthermore, one of the symptoms of Crohn’s is mucus in stool that results from a frequent inflammation of the colon and inflammation of the mucus-secreting glands, which requires palliative treatment. Other common symptoms of the condition include the following:

  • Abdominal pain
  • Fever
  • Fatigue
  • Loss of appetite and weight loss
  • Watery diarrhea that may be bloody

7. Food allergy

A very frequent pathology that can lead to the presence of mucus in the stool is food allergy. Many people are intolerant to certain foods, so their ingestion can precede the appearance of some of the following symptoms:

  • Constipation or diarrhea
  • Rashes
  • Abdominal distention

8. Anal fissures can lead to mucus in the stool

An anal fissure is a small tear in the skin and mucosa lining the anus. They can be the result of chronic constipation, large stools and anal sex. This condition conditions the appearance of mucus and blood in the stool. Other common symptoms include:

  • Pain while pooping
  • Discomfort and itching in the anal area
  • Sensation of rectal fullness or tenesmus
  • Small lump near the anal sphincter

Usually, this type of lesion resolves spontaneously after a couple of days. Studies affirm that the first line treatment is based on hygienic measures that include sitz baths and washing with neutral soaps, as well as the use of anesthetics and topical corticoids to relieve pain.

9. Irritable bowel syndrome

People with irritable bowel syndrome (IBS) are prone to intermittent mucus in the stool. Thus, this symptom is more frequent in IBS with predominant diarrhea. Similarly, the following manifestations are common:

  • Abdominal cramping
  • Abdominal distention and bloating
  • Change in the frequency and form of bowel movements

Research affirms that treatment includes lifestyle modifications and dietary changes, as well as the use of probiotics and pharmacotherapy aimed at improving intestinal motility and sensitivity. In general, prompt treatment decreases the risk of complications and improves quality of life.

When should you be concerned about mucus in the stool?

Finally, the presence of a small amount of mucus in the stool is normal in most cases, especially in people prone to constipation. This is because the rectum is a sensitive area that may experience slight lesions that explain this clinical manifestation.

However, if the mucus becomes abundant, appears more frequently and is accompanied by any of the symptoms described above, seek medical attention as soon as possible. This is because many of the above conditions can be detrimental to your health when not properly treated.

After knowing many of the causes of mucus in the stool, it’ll be much easier to determine the cause if you’re currently afflicted by it.

Likewise, if you know the reason, you can decide what type of treatment guided by your doctor will go best with the condition you’re facing. This way you’ll maintain the health of your large intestine at its maximum capacity and without any type of alterations in between.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

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  • Maroto N., Hinojosa J.. Colitis ulcerosa. Rev. esp. enferm. dig.  [Internet]. 2005  Ago [citado  2022  Mar  21] ;  97( 8 ): 602-602.
  • Rodríguez Palomo David, Alfaro Benavides Andrea. Actualización de la Fisiología Gástrica. Med. leg. Costa Rica  [Internet]. 2010  Sep [cited  2022  Mar  11] ;  27( 2 ): 59-68.
  • Aller de la Fuente R.. Enfermedad diverticular del colon. Rev. esp. enferm. dig.  [Internet]. 2005  Jun [citado  2022  Mar  21] ;  97( 6): 458-458.
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  • Porcel Ruiz J, Hernández Blaya R, Muñoz Galindo Á, Granados López B. Obstrucción intestinal como comienzo de la enfermedad de Crohn. Medicina General y de Familia. 2015;4(1):22-24.
  • Alonso-Coello P, Marzo-Castillejo M, José Mascort J, José Hervás A, et al. Guía de práctica clínica sobre el manejo de las hemorroides y la fisura anal (actualización 2007). Gastroenterología y Hepatología. 2008;31(10):668-681.
  • Camilleri M. Management Options for Irritable Bowel Syndrome. Mayo Clin Proc. 2018 Dec;93(12):1858-1872.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.