What Can Cause Mucus in Stool?

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It's normal for stool to have stringy, clear, white or yellow mucus in it. But when there is enough to be seen with the naked eye, it could be a sign that something in the digestive system is changing.

Mucus in the stool is a common symptom of some digestive conditions. Irritable bowel syndrome (IBS) and ulcerative colitis (one form of inflammatory bowel disease, or IBD) can cause it. So can bacterial infections, anal tears or fissures, a bowel obstruction, or Crohn's disease (the second main form of IBD).

If you notice blood in your stool, or if you have pain, it's a good idea to get in touch with a healthcare provider right away.

This article explores some of the main reasons mucus can show up in your stool. It also explains when you should seek medical treatment.

Causes of mucus in stool
Verywell / Nusha Ashjaee 


Several organs in the body produce mucus. In your lungs, for example, mucus helps to trap foreign particles you may have inhaled. Your large intestine also produces mucus. It protects the lining of your colon, creates a healthy environment for good gut bacteria and eases the passage of stool.

Mucus in the stool is not harmful in and of itself. But too much could be a sign of a disease or condition that needs treatment. If the mucus layer is shedding too much, it could make the colon more vulnerable to harmful bacteria.


Several conditions can lead to visible mucus in the stool. Here are some possibilities:

Ulcerative Colitis

In ulcerative colitis, the mucus membrane of the large intestine (colon) is inflamed. It develops small sores called ulcers. These ulcers can bleed and produce pus. They can also make enough mucus to be seen in the stool.

Irritable Bowel Syndrome

IBS often causes an excess of whitish mucus in the digestive system. It's more often associated with diarrhea-predominant IBS than with constipation-predominant IBS or alternating type IBS (IBS-A).

Men with IBS tend to have mucus in the stool more often than women with IBS.

Researchers aren't sure exactly why the condition results in so much extra mucus. Extra mucus with IBS does not mean there's a major problem or that the disease is becoming more serious.

Crohn's Disease

Passing mucus in the stool is less common in people with Crohn's disease. It can sometimes mean that you're developing an anal fissure or tear in the tissue of your anus.


Health conditions that cause inflammation in the bowel can create extra mucus in the stool.

Anal Abscess or Fistula

An abscess is an infection that creates a pocket of pus inside the body. It's a problem that occurs more often in people with Crohn's disease, particularly in the perianal area.

In about 50% of cases, an abscess gets large enough to form a tunnel between two organs, or between the skin and an organ. That kind of abscess is called a fistula. The abscess or fistula may drain mucus into the stool.

Abscesses and fistulas need treatment. Your healthcare provider may prescribe antibiotics or other medications. In some cases, the abscess will need to be drained.


Some people who have had ostomy surgery (either ileostomy or colostomy) may pass mucus from the rectum.

Stool leaves the body through the stoma, not the rectum and anus. But the rectum still creates fluid. You may still need to pass mucus by sitting on the toilet. If mucus builds up, it can cause discomfort and pressure. 

Bacterial Infections

Some bacteria can cause mucus in the stool, including:

  • Campylobacter
  • Salmonella
  • Shigella
  • Yersinia

Bacterial infections may also cause diarrhea, fever, and abdominal cramps.

Some bacterial infections get better on their own without treatment. Others may need antibiotics. If you think you may have a bacterial infection, especially after traveling abroad, call your healthcare provider.

Bowel Obstruction

If something blocks your bowel, you may notice excess mucus in your stool. Bowel obstructions can also cause:

A bowel obstruction could be caused by several conditions, including:

  • Impacted stool
  • Adhesions (scar tissue)
  • Hernia (tissue that bulges through a weak or torn muscle)
  • Gallstones
  • Tumor
  • Swallowing an object that isn't food

Obstructions are typically treated in the hospital. Sometimes the blockage has to be removed surgically.


If you have had surgery, an infection, or a blockage in your bowel, you may see mucus in your stool.

Cystic Fibrosis

Cystic fibrosis is a genetic difference that causes the body to make too much mucus. This condition most often affects the lungs, but it can also impact the digestive tract. The condition is usually diagnosed in childhood. Cystic fibrosis can also cause constipation and abdominal pain.

Mucus in Infant Stool

Mucus in the stool of an infant could mean the baby has an infection. It's important to find out if it is truly mucus, because normal baby poop comes in all colors. Mucus in baby stool might be stringy or slimy and look green.

Talk to your baby's doctor about changes in poop. If there is an infection, it will need to be treated right away.

Other Causes

Mucus can accompany constipation. It may resolve on its own when the constipation is treated.

Dehydration can also lead to excess mucus in the stool. It is likely to go away on its own unless dehydration is a chronic problem. In these cases, treating the underlying problem may resolve the issue of too much mucus.


Mucus in the stool could be caused by short-term conditions such as constipation or diarrhea. It could also be caused by a long-term disorder such as cystic fibrosis. If you see changes in a baby's stool, speak with a healthcare provider.

When to Talk to a Healthcare Provider

If you haven't been diagnosed with a health condition where excess mucus is a typical symptom, it's a good idea to discuss the problem with a healthcare provider even if it feels a little awkward. It's especially important if you're also seeing symptoms like these:

  • Blood in the stool
  • Diarrhea
  • Abdominal pain
  • Constipation
  • Vomiting

If you have a health condition that causes mucus in your stool, it's important to keep track of any changes to your stool.

Make a note of what time of day it happens and try to estimate how much mucus is present. You may also want to note whether it's more or less than in the past. You can discuss this information with a healthcare provider if you notice any changes in your body's patterns.


If mucus in your stool is new, diagnosing the cause will start with a thorough medical history. A healthcare provider will ask what your bowel movements were like in the past. You'll need to explain how they've changed recently.

Your healthcare provider may also order some tests to help pinpoint the cause. Stool cultures, blood tests, and imaging studies like CT scans, MRIs, or X-rays are often used as diagnostic tools.

In some cases, a healthcare provider may need to do other testing, such as an endoscopy, to figure out what is happening. Endoscopy is a test in which a small camera on a flexible tube is used to see the inside of the colon and rectum. In many cases, though, it's not necessary to do invasive testing to find the cause.


Your treatment will depend on the cause. If inflammation is the problem, treatment will focus on reducing the inflammation before it causes other symptoms.

When the mucus is caused by IBS or IBD, getting those conditions under control will help reduce mucus production in the large intestine. Excess mucus might mean a current treatment is no longer working well and a change needs to be made. 


A little mucus in the stool is normal. Mucus is produced in the intestine, where it helps to foster a healthy digestive system. If you can see mucus, however, it could mean that something new is happening in your digestive tract.

A number of health conditions can cause excess mucus. Irritable bowel syndrome, ulcerative colitis, Crohn's disease, bacterial infections, and cystic fibrosis can all ramp up your body's mucus production. So can anal fissures, bowel obstructions, ostomies, abscesses, and fistulas.

It's important to talk to your healthcare provider if you're noticing mucus in a baby's stool. It's also a good idea to seek medical care if mucus happens along with abdominal pain, blood in your stool, vomiting, and diarrhea or constipation.

You may need tests, including stool cultures, blood tests, imaging studies, or endoscopy to find out what's going on. A good diagnosis is the basis of effective treatment, so these tests will be worth your time.

A Word From Verywell

If you have IBS or ulcerative colitis, mucus in your stool isn't necessarily cause for alarm. But if mucus is new, whether you have a digestive health condition or not, it's a good idea to mention at your next healthcare visit.

Frequently Asked Questions

  • What does white mucus in stool mean?

    White mucus in stool is a symptom of irritable bowel syndrome (IBS). Common symptoms of this disease include abdominal pain often related to a bowel movement, a change in overall bowel movements (either diarrhea or constipation), and bloating. If you have these symptoms plus white mucus in your stool, contact your healthcare provider for a diagnosis.

  • How does Crohn's disease affect stool?

    Crohn's disease can affect stool in some people by causing diarrhea. Ileocolitis is the most common form of Crohn's disease. It causes inflammation of the terminal ileum (the end point of the small intestine) as well as the colon.

  • What does bloody mucus in stool mean?

    There are a number of reasons why blood or bloody mucus might be found in stool. It could be caused by hemorrhoids, anal fissures, polyps, gastroenteritis, angiodysplasia (caused by weakened blood vessels in the gut), or, less often, cancer. If you're not certain of the cause, check in with a healthcare provider as soon as possible.

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7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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