What are the common causes of pencil thin stools?

Reviewed by Yoshinori Abe, MD

Internal Medicine

Pencil-thin stools are narrow, ribbon-like bowel movements that can result from changes in bowel function, including those following surgeries such as a hysterectomy. While often benign, they may also reflect other underlying issues affecting the colon or rectum. In many cases, pencil-thin stools are not a sign of serious illness, but persistent changes in stool shape should not be ignored.

Because stool changes can have many causes—ranging from harmless dietary shifts to conditions requiring medical attention—understanding your specific symptoms is essential. Rather than guessing or worrying, take a few minutes to complete a free, instant, and confidential online symptom check. It can help you identify possible causes, decide whether to see a doctor, and confidently plan your next steps.

Reviewed for medical accuracy: 07/15/2026

Important Next Steps

Discover causes of pencil-thin stools See if your stools need care Find out if pencil-thin stools signal something serious Learn OTC options for thinner stools Find a doctor for stool concerns Discover home remedies for stool changes Understand likely causes of pencil-thin stools

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Explanation

Pencil thin stools, sometimes referred to as low caliber stools, can occur for a variety of reasons. According to the medical literature, these types of stools are not always indicative of a serious condition.

Post-Surgical Changes: One study suggests that changes in bowel function, such as those that may occur after a hysterectomy, can lead to alterations in stool shape and consistency.
Misconceptions: Another source emphasizes that low caliber or pencil thin stools are not definitive signs of specific diseases, contradicting common misconceptions that they are always linked to severe conditions.

It's important to note that while pencil thin stools can occasionally be a sign of a health issue, they are not inherently alarming and can result from benign changes in bowel habits. If you're experiencing changes in your stool or have concerns about your digestive health, you can check your symptoms with Ubie's free AI-powered tool to better understand what might be causing them.

(References)

Borhan-Manesh F. (2009). "Low caliber stool" and "pencil thin stool" are not signs of .... Digestive diseases and sciences, 18683051.
Aneese AM, Manuballa V, Amin M, & Cappell MS. (2017). Bladder urothelial carcinoma extending to rectal mucosa .... World journal of gastrointestinal endoscopy, 28690772.
van Dam JH, Gosselink MJ, Drogendijk AC, Hop WC, & Schouten WR. (1997). Changes in bowel function after hysterectomy. Diseases of the colon and rectum, 9369110.

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