Why You Have Fiber Strings in Your Poop

By Jennifer Nadel, MD
Medically reviewed checkmarkMedically reviewed
April 11, 2022

Though not always pleasant, keeping an eye on your stool’s appearance can be an important preventive health measure. 

A change in stool texture or consistency, like finding stringy or pencil-thin stools, can be a sign of an underlying problem.

A change in stool can also simply be a result of your diet. 

Understanding the possible causes of stringy, fiber-like stools can help you determine whether to seek medical attention.

In this article, I’ll explain the possible causes of stringy stools, other symptoms that may present, and when you may want to reach out to a healthcare provider for help with your digestive health.

What Is Stringy Poop?

Stool regularity and appearance can be important indicators of overall bowel health, and good bowel health can support a healthy digestive tract and body. 

Stringy stool is also sometimes referred to as “pencil-thin” stool.

Stringy or pencil-thin stool will look different from a well-formed stool, but it’s not necessarily a sign of an underlying condition. 

In some cases, stringy stool can be a result of your diet or how your muscles contract in the large intestine when working to concentrate waste.

Causes of Stringy Poop

Stringy poop isn’t always cause for concern.

There are several possible causes, some of which may require medical attention.


Many people experience constipation from time-to-time.

Symptoms and signs of constipation include:

  • Having fewer than three bowel movements per week
  • Having lumpy or hard stools
  • Straining to have bowel movements
  • Feeling like there’s a blockage in the rectum
  • Feeling like you’re unable to completely empty the stool from your rectum
  • Needing help to have a bowel movement, like using your hands to press on your stomach

For many, simple lifestyle changes can alleviate constipation, including incorporating more fiber into their diet, exercising more regularly, and staying hydrated.

But some people who experience chronic constipation may require different interventions, such as prescription or over-the-counter (OTC) medication and bowel retraining.

Undigested food in stool

Eating a high-fiber diet can result in seeing undigested food in stool, some of which may be stringy in appearance, like banana.

This isn’t usually cause for concern but if you’re experiencing any other symptoms, like nausea or fever, reach out to your healthcare provider as soon as possible.

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Irritable bowel syndrome (IBS)

Irritable bowel syndrome (IBS) refers to a group of abdominal symptoms that can occur together. 

Symptoms of IBS can include:

Stringy stool can also be caused by IBS.

Though experts aren’t sure what causes IBS, speaking with a provider about your history and symptoms can help them to make appropriate recommendations for lifestyle changes, medicines, probiotics, and other therapies that can help.


Stringy stool can also be a sign of an intestinal infection.

Gastrointestinal infections that can cause stringy stool include:

  • Giardia (giardiasis)
  • Salmonella
  • Gastroenteritis
  • Shigellosis

You can catch these infections through contaminated food or water or, in some cases, after close contact with someone who is sick.

The symptoms of an intestinal infection will vary depending on the type of infection you have.

Possible symptoms include:

Treatment will also vary depending on the type of infection present.

In the case of a parasitic infection (like giardia), your provider may recommend taking a prescription anti-parasitic medication to clear the infection. 

Other infections, like salmonella, may clear up on their own within a few days.

However, if you’re experiencing any severe symptoms, it’s important to reach out to your provider for treatment guidance. 

Colorectal cancer

In rare cases, stringy stool can also be a sign of colorectal cancer. 

Additional symptoms can include:

  • A change in regular bowel movements that lasts for more than a few days
  • A feeling like you need to have a bowel movement that isn’t relieved by having one
  • Bright red rectal bleeding 
  • Blood in stool, which may appear dark brown or black
  • Cramping or abdominal pain
  • Weakness
  • Fatigue
  • Unintentional weight loss
  • Night sweats

It’s important to note that these symptoms can also indicate a problem that isn’t cancer. In the case of colorectal cancer, it may take a while for any symptoms to develop.

Treatment of colorectal cancer will vary depending on the stage and your overall health.

Chemotherapy, radiation therapy, targeted drug therapy, and surgery may be options recommended to you by your healthcare and cancer care team.

Other medical problems

Other rare medical conditions can also cause stringy stools, including: 

  • Fecal impaction: This is when hardened stools remain in the bowels and cannot be passed with regular bowel movements. Fecal impaction can be particularly dangerous in the elderly. If you believe you have a fecal impaction, it’s important to see a medical provider who can evaluate your symptoms and recommend the proper treatment plan.
  • Colon polyps: These growths on the lining of your colon or rectum don’t always cause symptoms. But when they do, symptoms can include blood in stool and a change in stool. In most cases, your provider will use a special tool to remove the polyps from your colon during a colonoscopy. 
  • Trapped abdominal hernias: When a hernia (a bulging of the contents of the intestines through a weak area in the lower abdominal wall) gets trapped and cannot be pushed back into the abdominal wall, you may experience bowel obstruction and/or stringy stool. This is a medical emergency and if this happens, you need to go to the closest emergency department.  
  • Stricture: An anorectal stricture refers to a narrowing between the rectum and anus which can cause changes to stool, including stringy stool.
  • Twisted bowel (volvulus): Volvulus describes when a loop of intestine twists around itself, causing bowel obstruction. Several conditions can cause volvulus, including Hirschsprung disease, an enlarged colon, and pregnancy. However, volvulus is most common in older men with a history of chronic constipation. This is a medical emergency and treatment often requires surgery.


Finding stringy stool every now and then is not usually a serious medical concern.

However, if you’re having stringy stool for more than a week, or if you’re experiencing additional symptoms, make an appointment with your provider as soon as possible. 

Additional symptoms that may warrant urgent or emergent medical attention include:

  • Blood in stool
  • Black, tarry stools
  • Stool that is very light or pale in color
  • Floating stools that appear greasy or fatty
  • Unintentional weight loss
  • Very dark-colored urine
  • Fever
  • Fast or rapid heartbeat
  • Nausea
  • Vomiting
  • Abdominal pain
  • Distended abdomen
  • Slow reflexes
  • Severe, persistent abdominal pain, or abdominal pain that begins in the upper abdomen and spreads to the back or lasts for several days

When working with your healthcare provider, they may recommend one or more of the following tests to determine the cause of your stringy stool and which treatment plan, if any, is right for you:

  • Fecal occult test to check for blood in stool
  • Stool sample test to check for an infection
  • Blood test to check for other diseases or conditions
  • Imaging of your abdomen and pelvis such as a CT scan, ultrasound, or x-ray 
  • Colonoscopy or endoscopy

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When To See a Doctor

In most cases, having stringy stool is not cause for concern.

However, if you’re in pain or experiencing other symptoms, it’s important to speak to a medical professional as soon as possible. 

How K Health Can Help

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Download K Health to check your symptoms, explore conditions and treatments, and, if needed, text with a clinician in minutes. K Health’s AI-powered app is based on 20 years of clinical data.

K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Jennifer Nadel, MD

Dr. Jennifer Nadel is a board certified emergency medicine physician and received her medical degree from the George Washington University School of Medicine. She has worked in varied practice environments, including academic urban level-one trauma centers, community hospital emergency departments, skilled nursing facilities, telemedicine, EMS medical control, and flight medicine.

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