Causes of Mucus in Stool

Mucus in stool is normal, but it's not usually visible to the naked eye. When it is—you may notice stringy clear, white, or yellow goop in the toilet or clinging to your poop—it could be a sign of a health concern that needs treatment.

Possible causes of mucus in your stool include irritable bowel syndrome (IBS), ulcerative colitis, Crohn's disease, and other digestive disorders. Bacterial infections, bowel obstructions, and anal tears (fissures) also can cause it.

This article explores some of the main reasons mucus can show up in your stool. It also explains when you should seek medical treatment and how a healthcare provider will figure out the cause.

Mucus in Stool Causes

Several conditions can lead to visible mucus in the stool, including:

• Ulcerative colitis
• Irritable bowel syndrome
• Crohn's disease
• Anal abscess or fistula
• Ostomy
• Bacterial infection
• Bowel obstruction
• Cystic fibrosis

Ulcerative Colitis

In ulcerative colitis, the mucus membrane of the large intestine 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 (IBS-D) than with constipation-predominant IBS or alternating type IBS (IBS-A).

Anxiety and stress may cause mucus in the stool when it coexists with IBS-D. That's also true of depression, which has long been associated with IBS symptoms and diagnosis.

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 a tear in the lining of the anus.

However, 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 (large intestine).

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. This 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 surgically drained.

Ostomy

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

With an ostomy, stool leaves the body through the stoma, not the rectum and anus. But the rectum still creates fluid. If mucus builds up, it can cause discomfort and pressure. This can be passed by sitting on the toilet.

Bacterial Infections

Some bacterial infections can cause mucus in the stool. These infections include:

• 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:

• Constipation
• Severe cramps
• Abdominal bloating
• Vomiting

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.

Cystic Fibrosis

Cystic fibrosis is a genetic condition that causes the body to make too much mucus. The mucus most often affects the lungs, but it can also impact the digestive tract.

The lifelong condition is usually diagnosed during childhood. Cystic fibrosis can also cause constipation and abdominal pain.

Other Causes

Mucus in stool 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.

When to Talk to a Healthcare Provider

If you haven't been diagnosed with a health condition that typically causes excess mucus in stool, it's a good idea to discuss what you're experiencing with a healthcare provider.

It's especially important to see your provider about the following:

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

If you have a health condition that affects your colon and your stool, make sure you keep track of any changes to your stool and discuss any changes with your healthcare provider.

The mucus produced by your colon protects the lining, creates a healthy environment for good gut bacteria, and eases the passage of stool. If the mucus layer is shedding too much, it could make the colon more vulnerable to harmful bacteria.

Diagnosis

If you are first noticing mucus in stool, see your healthcare provider. Diagnosing the cause will start with a thorough medical history. They will ask what your bowel movements were like in the past and what has changed.

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 why there is mucus in your stool. 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.

Treatment

Mucus in stool itself isn't harmful, but the cause may require treatment. What you need depends on what's affecting you.

If inflammation is the problem, for example, 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 to 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. 

Summary

Mucus is produced in the intestine, where it helps to foster a healthy digestive system. Mucus in stool isn't necessarily serious. But excess mucus could mean that something new is happening in your digestive tract.

A number of health conditions, including IBS or a bacterial infection, can ramp up your body's mucus production. So can anal fissures and bowel obstructions. Mucus may appear in a baby's stool too.

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 get a proper diagnosis and begin effective treatment.

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 or increasing, it's a good idea to mention that at your next healthcare visit.