What Causes Narrow Stools And How To Treat It?

Narrow stools
Medically reviewed by Dr. Mehvish Khan


The term “narrow stool” describes faeces smaller in diameter than usual and identifies several health problems. Narrow stools may be caused by constipation, irritable bowel syndrome (IBS), colon cancer, or other gastrointestinal conditions. Your healthcare provider can help identify the problem and provide effective remedies. See a doctor right away if your stools are kept thin.

What is Narrow Stool?

The narrow stool is referred to as pencil-thin, ribbon poop, or narrow-shaped stringy poop. In some cases, it’s both narrow and flat stool. It could be rigid or fluid. Its estimated diameter is somewhere between one to two inches.

Narrow stool that is a symptom on its own can be experienced in combination with additional gastrointestinal symptoms like nausea and cramping in the stomach.

In order to know what your springy narrow poop is trying to indicate, let’s have a look at the causes in detail.

Causes of Narrow Stool:

Causes of Narrow Stool can be both dependent and independent. Independent causes are in your control, like your dietary intake, but independent causes are out of your reach! Because it’s some infection or disease that makes your poop shape unusual.

Here are some most commonly known causes of narrow stool.

Low Fiber Diet:

Diet is the most influencing factor that can help maintain healthy bowel movements and frequency. When it comes to a thin narrow poop, it is most likely to be experienced by obstructions that develop in the colon due to chronic constipation. As a result, the stool size may be reduced, making it seem narrow and stringy. Constipation occurs more often if you eat a diet low in fiber.

As this cause is dependent upon your dietary intake, it can easily be managed by adding insoluble fiber to your diet.

Intestinal Infection 

Intestinal infection is considered an independent cause of where the body may experience altered bowel movements and skinny stools. Infection can be mostly in the colon, for example, gastroenteritis. Thin stools may result from a constricted stoma channel caused by inflammation of the intestines.

Inflammatory bowel syndrome (IBS):

Inflammatory Bowel Syndrome, a condition of the large intestine, may lead to abnormal bowel movements and frequency. It causes swelling in the intestine that ultimately alters the stool shape and turns it into a narrow pencil poop. 

Gastrointestinal parasite infections:

Parasites can be the silent enemy that is actually causing a disturbance. Gastrointestinal Parasites, also known as roundworms such as little worms, might cause thin and narrow stool or diarrhea. They can survive in your gut after living in the soil and getting into your diet. 

 Other Causes:

The following are also considered the causes of narrow stools:

  • Anorectal stricture is a dilated or constricted colon, Obstructing the rectum and anus.
  • A tiny growth or polyp in the colon, known as fecal impaction, or a mass of hard stools trapped there.
  • Colon inflammation carried on by Crohn’s disease or ulcerative colitis 
  • Abdominal Hernias
If the Cause of Narrow Stool is Still Unknown? Consult a Doctor and Figure Out the Root Cause!

Medical Conditions Associated with Narrow Stool:

Following are the common coexisting or related medical conditions with narrow stools. 


Hemorrhoids, often known as piles, are most likely swollen veins similar to varicose veins in the lower rectum and anus. Hemorrhoids can form under the skin around the anus (external hemorrhoids) or inside the rectum (internal hemorrhoids)

Narrow stools may result from haemorrhoids. Numerous factors might lead to haemorrhoids, including:

  • Straining when having bowel movements
  • Spend a lot of time on the toilet
  • Persistent diarrhea or constipation
  • Consuming low-fiber food
  • Lifting heavy objects repeatedly
  • Being overweight or obese
  • Pregnancy 

Usually, increased abdominal pressure causes hemorrhoids to form.


Diverticula are small, sharp-edged pouches that can develop in the lining of your digestive tract. They are most usually found in the lower part of the large intestine (colon). When diverticulosis significantly worsens, the lower colon may become highly fixed, twisted, and restricted. It can lead to constipation, thin or skinny poop, and the sporadic start of diarrhea.

Fecal Obstruction:

Fecal impaction, similar to constipation, occurs when a  bulk of dry stool is stuck or lodged in the rectum and blocks the path of stool and making evacuation difficult. Thin feces pass through the blockage.

Colorectal Cancer:

Narrow stools could indicate a cancerous gut tumor around the anus. Pencil-thin stool might be the only thing that can pass through the obstruction if it is big enough to stop the stool from moving through the intestine.

Anal Cancer:

Skinny stool caused by HPV (human papillomavirus)may result from this rare form of cancer. Feeling bloated and rectal bleeding are common symptoms.

Crohn’s Disease and Ulcerative Colitis:

Changes in the stool can result from Crohn’s disease. The feces’ frequency, consistency, and appearance may differ from normal due to the inflammation (swelling and redness) and ulcers carried on by Crohn’s disease in the small or large intestine.

Twisted bowel (Volvulus): 

The term “Volvulus” means when an intestine loop bends around itself and obstructs the gut. In several disorders, Volvulus may transmit diseases like Hirschsprung disease. 

Risk Factors of Narrow Stools:

  • Age
  • A family history of the condition
  • Personal history of inflammatory bowel disease
  • A diet rich in red or processed meat
  • A sedentary lifestyle is a risk factor for colorectal cancer
  • A history of abdominal surgery, particular drugs, and specific medical diseases like Crohn’s Disease are risk factors for intestinal blockage.
Is Narrow Stool is Indicating Disease Risk? Talk to a Doctor and Get Diagnosed.


If you frequently see changes in the appearance of stool or it may be narrower than usual, your doctor can refer you to a rectal or colon specialist who can suggest various tests to diagnose the disease. Several methods could be recommended.

Fecal Occult Test:

A fecal occult test (FOBT) is performed to find hidden blood in stool samples. This test is carried out to check for colorectal cancer and other gastrointestinal conditions that may result in gastrointestinal bleeding. The FOBT test takes a tiny feces sample and checks in a lab to identify whether blood is present. The guaiac-based FOBT (gFOBT) and the fecal immunochemical test are the two types of FOBT assays (FIT). To detect the presence of blood in the stool, the gFOBT test uses a chemical called guaiac that is added to the sample, and the resulting combination will turn blue.

Stool Sample Test:

A doctor can also recommend doing a stool sample examination for infections. Using a stool culture, the doctor can check whether the intestines are contaminated with bacteria.

Little samples of stool are put by a technician in sterile plastic dishes with nutrients that promote the growth of particular bacteria. Growth will occur only if the targeted bacteria are already present in the stool sample.

Blood tests to detect infection:

The process of having blood tested is simple and common. Lab attendants examine particular biomarkers that analyze the blood changed composition. When inflammatory bowel disease is present, a blood test will show an increased white blood cell count, which could indicate inflammation.

Imaging tests

Following tests are required to get the right diagnosis 

  • CT Scan
  • Ultrasounds
  • X-ray imaging of your abdomen and pelvis

The doctor may occasionally use a CT scan or X-ray to obtain a better image of the colon and rectum. These examinations can reveal further information regarding the internal structure of the organs and other abnormalities.

Endoscopy or colonoscopy:

Medical techniques like endoscopy and colonoscopy can help identify the root cause of thin stools. In these procedures, a doctor may insert a long, flexible tube with a camera at one end into the colon and rectum to check their linings.

When a patient experiences thin stools, the doctor may detect a constriction or obstruction in the colon or rectum. The position and size of any blockage can be determined by means of endoscopy or colonoscopy.

The doctor may do a biopsy, which comprises collecting a microscopic tissue sample for analysis if an obstruction is found. It can help determine whether a tumor, scar tissue, or inflammation is the cause of the obstruction.

Flexible Sigmoidoscopy: 

Another medical diagnostic procedure that can be performed to find the cause of narrow stools is flexible sigmoidoscopy. Like a colonoscopy, this operation focuses on inspecting only the rectum and the bottom part of the colon, called the sigmoid colon.

During a flexible sigmoidoscopy, a doctor inserts a flexible tube that has a camera on its end into the rectum and sigmoid colon. Making it possible for the doctor to identify any irregularities, including inflammation, polyps, or tumors, on the lining of these organs.

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Narrow Stool Treatment:

Following treatment options are most commonly applied during clinical practices.


If enema and manual removal are failed, a doctor may advise laxatives. They increase the amount of water the colon produces, softening the impacted stool and facilitating removal.

Stool Softeners: 

Stool softeners are prescription drugs that ease constipation and improve bowel movements. Stool softeners make stools easier to pass by increasing the amount of water and fat in the stool. Stool softeners, which produce softer, easier-to-pass feces, can help reduce symptoms of narrow stool disease.

Water Irrigation: 

A short tube irrigating the colon is pushed into the rectum. A machine that emits water through a tube is connected to the hose. After the irrigation, your doctor will massage your abdomen to help another tube remove the waste from your rectum.

Increasing Water Consumption: 

Drinking more water is a quick and efficient way to ease the symptoms of a narrow bowel movement. Water is necessary to keep a soft bowel movement and avoid constipation, which can result in pencil poop and difficulty in releasing.

Fiber-rich diet

You can promote regular bowel movements and avoid constipation by increasing your diet with high-fiber meals, including fruits, vegetables, and whole grains. It is very important for narrow stool disease because constipation worsens symptoms.


Surgery might be necessary in some cases of narrow stool illness, particularly if a physical obstruction or structural issues are responsible for the symptoms.

For the treatment of narrow stool disease, the following surgical methods could be used.

Bowel resection:

In this procedure, a segment of the bowel that has been obstructed or narrowed is removed. Reconnecting the remaining intestinal ends restores normal bowel function.


This treatment includes making lengthwise incisions and then suturing the incisions to increase the diameter of the gut to enlarge a narrowed segment of the colon.

Colostomy or ileostomy: 

In some circumstances, a temporary or permanent opening (stoma) may be made in the abdomen to allow stool to flow through a constricted or blocked part of the colon.

Anticholinergic medicines: 

Acetylcholine is a neurotransmitter in the body involved in various biological activities, including regulating bowel movements. Anticholinergic medications are a type of medicine that suppresses this neurotransmitter’s action. Anticholinergic drugs may occasionally be used to treat symptoms of thin stools.

Anticholinergic drugs treat constipation by relaxing the smooth muscles of the intestines, which might promote more frequent bowel movements.


Painkillers are commonly not advised for treating narrow stools since they can worsen the symptoms of constipation and narrow stools. Opioids and other painkillers can slow the passage of stools through the digestive tract and lead to constipation, making feces more difficult to pass. In some circumstances, non-opioid painkillers, physical therapy, or other non-pharmacological treatments may reduce pain.


Narrow stool disease may be treated with specific antidepressants. Narrow stool disease can be treated with tricyclic antidepressants (TCAs), a particular class of antidepressantsTCAs function by preventing the brain from absorbing certain neurotransmitters, which can help in mood regulation and anxiety reduction. Moreover, these drugs might stimulate regular bowel motions and ease constipation.

Radiation and Chemotherapy: 

The treatment plan for colorectal and anal cancer is determined by the cancer’s stage, where the tumor is located, and other circumstances like the patient’s age and general health. Radiation therapy, chemotherapy, and surgery are frequently used in combination for treatment.

When to Consult a Doctor

If your bowel motions change or you have prolonged thin stools, consult your doctor; it can signify a more serious medical problem that needs to be investigated and treated. Call your doctor immediately if your bowel changes are accompanied by severe stomach discomfort or rectal bleeding.

Narrow Stool May Indicate a Serious Disease, Talk to Our Doctor to Find Out

FAQS about Narrow Stools Answered by Your Doctor Online

What Medications Can Cause Thin Stools?

NSAIDs, often called nonsteroidal anti-inflammatory drugs, include aspirin, ibuprofen, and naproxen. These medications may disrupt the digestive tract’s lining and cause bleeding, which may cause thin stools.
Heparin and Warfarin can also increase the risk of gastrointestinal bleeding, resulting in narrow stools. Antibiotics like penicillin or clindamycin may alter the normal bacterial balance in the gut, changing bowel patterns and causing thin stools by taking supplementing iron. Thin stools may arise from constipation brought on by iron supplementation. Antacids with aluminum hydroxide may result in constipation, which might cause pencil poop.

What is a normal stool supposed to look like?

The color of normal faeces ranges from tan to espresso and is always brown.

What does a healthy bowel movement look like?

Although the appearance of a good bowel movement might vary, it should typically be easy to pass and smooth.

Can stress and anxiety cause thin stools?

According to research, high-stress levels can disturb the digestive system, resulting in thin stools.

Can polyps cause narrow stools?

Polyps could be a condition that could impact how stool passes through or leaves the colon, causing narrow stool.

What does green poop mean?

Green poop is usually due to consuming green meals, such as leafy green vegetables, taking iron supplements, and having insufficient bile in your faeces.

Why is there thin stool and gas?

IBS patients suffer from diarrhea, faeces that change in texture and shape, gas, bloating, and constipation.

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