Symptoms and conditions
Mucus in stool: causes, what is normal and when to worry
A small amount of mucus in the stool is normal. The bowel makes it to protect its lining and help stool pass. Visible mucus on its own, with no other symptoms, is most often harmless and is common in irritable bowel syndrome. Mucus with blood, fever, weight loss or diarrhoea that lasts more than two weeks needs a medical assessment.
In short
- Mucus is a normal product of the bowel lining. You usually do not see it.
- Clear or white mucus without other symptoms is rarely a sign of disease.
- Mucus with blood, pus, fever or persistent diarrhoea suggests infection or inflammation.
- A stool test and, where needed, a colonoscopy find the cause.
What is mucus, and why is it there?
Mucus is a slippery gel made by cells in the lining of the intestine. It coats the lining, keeps bacteria at a distance and lubricates the passage of stool. It is clear, white or slightly yellow.
What causes visible mucus?
Irritable bowel syndrome
The commonest cause. Mucus is passed with or around the stool, along with pain and altered bowel habit, but without blood. See IBS.
Constipation and straining
Hard stools irritate the lining of the rectum, which responds by making more mucus.
Gut infections
Bacterial and amoebic infections cause loose stools with mucus, often with blood, cramps and fever. These are common in India and are treatable.
Inflammatory bowel disease
Ulcerative colitis and Crohn’s disease cause mucus with blood, urgency and night-time stools. See inflammatory bowel disease.
Polyps and growths
Certain polyps, and occasionally a cancer of the rectum, produce a great deal of mucus. See colon polyps.
After antibiotics
A particular infection that follows antibiotic use causes watery diarrhoea with mucus.
Food intolerances
Lactose intolerance and coeliac disease can increase mucus along with loose stools.
How do I tell harmless from worrying?
| More likely harmless | Needs a check |
|---|---|
| Clear or white mucus | Mucus with blood or pus |
| Comes and goes | Present daily for more than two weeks |
| No fever, normal weight | Fever, weight loss, poor appetite |
| Sleep is undisturbed | Waking at night to pass stool |
| A long history of similar symptoms | A new symptom after the age of 45 |
When should I see a doctor?
See a doctor if you have
- Blood or pus with the mucus
- Diarrhoea for more than two weeks
- Fever or severe abdominal pain
- Weight loss or a low blood count
- Stools that wake you at night
- A family history of bowel cancer or colitis
Which tests are done?
- Stool tests for infection, parasites and a marker of inflammation
- Blood tests for anaemia and inflammation
- Colonoscopy with tissue samples when inflammation, polyps or a growth is suspected
What can I do myself?
If you have mucus alone and feel well:
- Soften the stool with fibre and fluids, and avoid straining
- Note whether it follows particular foods, such as milk
- Avoid unnecessary antibiotics and painkillers
- See a doctor if it persists beyond two to three weeks or any warning sign appears
Do not treat suspected infections yourself with leftover antibiotics. The wrong antibiotic can prolong the illness.
Questions patients ask me
Is mucus in the stool a sign of cancer?
Rarely. Bowel cancer far more often shows as bleeding, a lasting change in bowel habit or anaemia. Persistent mucus with any of these should be examined.
Is mucus in the stool normal in IBS?
Yes. It is a recognised feature of IBS and does not mean the bowel is damaged.
Can stress cause mucus in the stool?
Stress can worsen IBS, and with it the passing of mucus. It does not cause inflammation or infection.
Does mucus mean I have worms or an infection?
It can, particularly with loose stools, cramps or fever. A stool test answers the question, and treatment depends on what is found.
Sources
This page is written for patients and is based on the guidelines and studies below. It is for education and does not replace a consultation.
- American College of Gastroenterology guideline on irritable bowel syndrome. Lacy BE et al. Am J Gastroenterol. 2021. doi:10.14309/ajg.0000000000001036
- American College of Gastroenterology guideline on ulcerative colitis in adults. Rubin DT et al. Am J Gastroenterol. 2019. PubMed 30840605
- American College of Gastroenterology guideline on colorectal cancer screening. Shaukat A et al. Am J Gastroenterol. 2021. PubMed 33657038