Narrow or Thinning Stool
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Try one of these related symptoms.
Thin stools
Long and thin poop
Stringy poop
Pencil thin stools
Poo became thin
Narrow stools
About the Symptom
Decrease in poop size or shape causing your poop to look narrow or pencil-like.
When to See a Doctor
Seek professional care if you experience any of the following symptoms
- Thin narrow stool
Possible Causes
Generally, Narrow or thinning stool can be related to:
- Colon Cancer
Cancer of the large intestine which is the final part of the digestive tumors. It often grows from non-cancerous polyps in the intestine. Both polyps and colon cancers can be found during colonoscopy (camera test of colon). Symptoms can include blood in stool, diarrhea or constipation or both, or abdominal pain but many times there are no symptoms and the cancer is found on colonoscopy. It can be easily treated in early stages, so the general population is encouraged to get screened with colonoscopy and sometimes stool tests. Risk factors include a family history of colon cancer or polyps, or a personal history of abnormal polyps, low-fiber high-fat diets, some inflammatory bowel diseases, diabetes, obesity, and lack of exercise.
- Colonic Polyp
Colonic polyps are benign growths that appear on the inner lining of your large intestine. Some have a chance of becoming malignant or cancerous over time.
Related Serious Diseases
Sometimes, Narrow or thinning stool may be related to these serious diseases:
- Diverticular Bleeding
The walls of the intestines sometimes have small pouches called diverticula. Risk factors include chronic constipation, aging, and obesity.
Doctor's Diagnostic Questions
Your doctor may ask these questions to check for this symptom:
- Is your stool thin and narrow like a pencil?
- Are your stools greasy and smelly?
- Is there mucus in your stools?
- Have you noticed any changes in the shape of your stool?
- How often do you experience an abnormal stool shape?
Reviewed By:
Samantha Nazareth, MD (Gastroenterology)
Board-certified gastroenterologist. Experience managing gastrointestinal conditions (GERD, IBS, ulcerative colitis, Crohn’s, celiac disease, NASH) within healthcare organizations (three ambulatory surgical centers, single-specialty practice, multi-specialty practice and solo practice).
Aiko Yoshioka, MD (Gastroenterology)
Dr. Yoshioka graduated from the Niigata University School of Medicine. He worked as a gastroenterologist at Saiseikai Niigata Hospital and Niigata University Medical & Dental Hospital before serving as the Deputy Chief of Gastroenterology at Tsubame Rosai Hospital and Nagaoka Red Cross Hospital. Dr. Yoshioka joined Saitama Saiseikai Kawaguchi General Hospital as Chief of Gastroenterology in April 2018.
Content updated on Feb 6, 2025
Following the Medical Content Editorial Policy
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