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Causes of Mucus in Diarrhea

Your stool always contains mucus, but when it contains amounts you can see it can indicate a gut health problem.
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Written by
Judy Kim, MD, MS.
Fellow, New York Presbyterian Hospital/Columbia
Last updated April 29, 2021

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Diarrhea with mucus can be caused by a viral infection, food poisoning, or a sign of a chronic problem in your intestines.

Mucus is produced by your intestines to keep your colon lubricated, which makes it easier for stool to pass. Stool normally has small amounts of mucus, but usually you do not notice it.

Diarrhea that looks like mucus or contains a larger amount of mucus may signal an underlying inflammatory condition, such as a food intolerance, gastrointestinal infection, irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), or hemorrhoids.

Pro Tip

Mucus in stool is not abnormal. Mucus is produced by the colon to help lubricate the stool. It becomes abnormal when you notice a lot more mucus than usual with ongoing diarrhea or if it is accompanied by blood. —Dr. Judith Kim

Causes

1. Irritable bowel syndrome

Symptoms

Irritable bowel syndrome (IBS) is a chronic digestive disorder. Symptoms can include abdominal cramping and bloating, diarrhea or constipation (or both), and having little control over when you need to go.

IBS may affect gut motility (how quickly it digests food) and gut inflammation, which increases mucus production in the intestines. Up to 50% of people with IBS say they have mucus in their stool. IBS can have flare-ups that can be more intense and uncomfortable than other times. Stress, diet, and other factors may cause flare-ups.

If you notice changes in your bowel movements, such as increased mucus, incontinence, or urgency, you should see a doctor to discuss these symptoms. Diet changes or medications may be recommended to help with your symptoms.

2. Bacterial infection

Symptoms

Bacterial infections can lead to increased mucus in the gut. The mucus may be yellow or greenish. Bacterial infections can be caused by foodborne illnesses, such as salmonella or E.coli, and other infections like Campylobacter, Shigella, and Yersinia.

Some infections can be treated with antibiotics. Gastroenteritis usually gets better on its own and it’s important to drink lots of fluids.

If you notice blood in your stool or your temperature is above 100.4°F, call your doctor. You may need to have a stool test to find out what type of infection you have. Your doctor may prescribe antibiotics.

If there is a lot of blood in your stool or you can’t keep any food or water down, you should go to the ER since there is a risk of serious dehydration.

Mucusy diarrhea questionnaire

Use our free symptom checker to find out what's causing your mucusy diarrhea.

Mucusy diarrhea symptom checker

3. Inflammatory bowel disease

Symptoms

  • Diarrhea or constipation, with stools that may have mucus or blood
  • Urgency or incontinence of stool
  • Abdominal cramps or discomfort

Inflammatory bowel disease (IBD) is a chronic condition that creates inflammation in the digestive tract. There are two types: ulcerative colitis and Crohn’s disease. Colitis affects the rectum and extends up through the entire colon, while Crohn’s looks like patches of inflammation throughout the colon or small intestine.

Both types of IBD can lead to frequent loose stools with mucus and blood. You may also have crampy abdominal pain, rushing to the bathroom, discomfort when having a bowel movement, and feeling like you haven’t completely emptied your bowel. If you notice these symptoms, you should see a gastroenterologist (digestive disease doctor).

Your doctor may recommend further tests or a colonoscopy to make a diagnosis. If you have IBD, you will need to start medications to help decrease the inflammation in your colon. Some patients may need surgery if their disease is severe.

Dr. Rx

If I hear that there is a small amount of blood only on the toilet paper, then I would think about hemorrhoids. If there is a lot of blood in addition to abdominal pain, I would be worried about inflammatory bowel disease or a different disease that needs a colonoscopy to better differentiate. —Dr. Kim

4. Food intolerance

Symptoms

  • Diarrhea, which may be streaked with mucus
  • Abdominal pain or discomfort
  • Gas or bloating

Food intolerances can lead to increased mucus in stool.

Some people may find certain foods cause abdominal discomfort and diarrhea. A common one is lactose intolerance, which is a reaction to lactose that’s found in dairy foods and drinks. Others include intolerance to gluten or spicy food. Treatment is to avoid these dietary triggers.

Keep track of what you’re eating in a food diary and bring it to your doctor who can help identify what is causing the symptoms. Trying an elimination diet where you stop eating trigger food groups may improve your symptoms.

An allergy doctor can help to pinpoint your allergies and intolerances through a skin test or blood test. Seeing a nutritionist can also help you create a diet plan that avoids your dietary triggers.

5. Hemorrhoids

Symptoms

  • Blood on toilet paper or blood or mucus in stool
  • Rectal pain
  • Itching in the anal area

Hemorrhoids are swollen veins in the rectum. You may feel or see some hemorrhoids outside the rectum (external hemorrhoids), while others are inside (internal hemorrhoids).

They are common and can cause bleeding, itching or pain. There can also be mucus in the stool or toilet paper.

Hemorrhoids can be caused by hard stools or straining when going to the bathroom. They often improve with over-the-counter medications, such as stool softeners, fiber, or topical creams (like Preparation H or witch hazel). Daily sitz baths are also helpful.

If your symptoms do not improve or you notice a lot of blood in your stool, see your doctor. If the hemorrhoids are severe, your doctor may recommend a colonoscopy or procedure to remove them.

Other possible causes

A number of conditions may also cause mucus in diarrhea.

Inflammatory

  • Infectious: Bacterial, viral, and parasitic infections can cause diarrhea that looks like mucus. They can directly infect the cells of the digestive tract and cause irritation that causes diarrhea. Common foreign invaders include rotavirus, norovirus, E. coli, salmonella, and giardia. When traveling in developing countries, diarrhea caused by bacteria and parasites is often called traveler's diarrhea.
  • Genetic: Many genetic conditions, such as cystic fibrosis, can cause chronic irritation that leads to diarrhea.
  • Autoimmune: Conditions with an autoimmune component can also cause diarrhea with mucus. This includes celiac disease, which is an immune reaction to gluten.

Environmental

Environmental causes can be related to certain exposures or lifestyle habits.

  • Diet: Not only can viruses and bacteria infect the digestive tract through contaminated food and drink, but a specific diet can also contribute to diarrhea that looks like mucus. Allergies to foods such as cow’s milk, soy, cereal grains, eggs, and seafood may cause chronic diarrhea.
  • Medications: Many medications have diarrhea as a side effect. For example, antibiotics destroy both good and bad bacteria and disturb the natural balance of bacteria in the intestines. That can lead to diarrhea with mucus or another infection, like C. Difficile colitis. Many other drugs that also destroy or distress the intestines, such as cancer drugs, can also cause diarrhea.

Mucusy diarrhea questionnaire

Use our free symptom checker to find out what's causing your mucusy diarrhea.

Mucusy diarrhea symptom checker

When to call the doctor

  • You continue to see mucus in stool even after changing your diet.
  • You see blood in the toilet or mixed with your stool.
  • You have abdominal or anal pain.

Pro Tip

Ask your doctor if you may need further evaluation with blood work or stool studies, especially if your symptoms are very bothersome or lasting a long time. —Dr. Kim

Should I go to the ER for mucus in diarrhea?

You should go to the emergency department if you have diarrhea with mucus and these symptoms:

  • You have severe abdominal pain or cramps.
  • You see significant blood in the stool.
  • You are feeling dehydrated and cannot drink enough liquids.

Treatment

At-home care

  • Make sure you are drinking enough liquids.
  • Avoid dietary triggers, such as dairy products if you’re lactose intolerant.
  • Take a sitz bath (sitting in warm water) or use topical creams if you have anal pain.

Other treatment options

  • Medications such as antibiotics or anti-diarrheal agents.
  • Procedures such as a colonoscopy to help with a diagnosis.
Share your story
Fellow, New York Presbyterian Hospital/Columbia

Dr. Kim is a Gastroenterology Fellow at New York Presbyterian Hospital/Columbia University where she also completed her residency training in Internal Medicine. She received her medical degree at Washington University in St. Louis and earned her BA in Biology at Harvard College. Her specialty is Gastroenterology, with a research interest in gastric cancer and clinical outcomes.

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