Flat Poop: Causes, Diets, Diseases & Remedies

  • 1st Revision: Chloe Vilenstein


Have you noticed that your poop looks different to normal? Maybe you have noticed that your stools have a pencil-like shape.

Flat poop may be the result of constipation, diarrhoea, IBS, diet, or medications.

Read on to learn everything you need to know about flat poop.


Sometimes, stools can be flat without any known cause. Flat poop can be temporary and may be nothing to worry about. However, if you are experiencing flat poop frequently, an underlying condition could be causing this.

It is essential to check with your doctor if you are frequently experiencing flat poop, especially if there are coinciding symptoms such as blood in your stools, changes in your bowel habits, stomach pain, and fever. 


Flat poop may also be the result of a variety of other conditions which affect the normal functioning of your bowels. For example, flat poop may be the result of:

  • Irritable bowel disease
  • Faecal impaction
  • Haemorrhoids
  • Abdominal hernia


The food you eat impacts how your poop looks. Similar to how green poop can be seen after eating some green vegetables, eating certain foods may cause thin stools. You may notice flat poop when you are:

  • Not eating enough fibre. Fibre helps to increase the weight and size of your stools and will make your stools softer1
  • Not drinking enough fluids. Liquids will help to loosen your stools and make them easier to pass2
  • Eating certain trigger foods. Trigger foods refer to foods which may irritate your stomach and cause flat poop. Your body’s reaction to trigger foods is usually a result of conditions like IBS3


Medications may cause differences in poop shape, size, and frequency. It is no surprise that laxatives affect how your poop looks, but other medications can also influence your bowel movements:


How flat poop looks

Normal stools should be sausage-shaped, round, and smooth, with some cracks on the surface. However, as the name suggests, flat poop isn’t round or sausage-shaped. Flat poop has a string-like appearance and may occur alongside loose stools (diarrhoea). 

Texture of flat poop

The texture of stools can vary from soft and firm, to hard lumps, which are more difficult to pass. Flat poop may have a variety of textures.

The texture of poop will also depend on whether you are experiencing diarrhoea or constipation. The Bristol Stool Chart will help you identify whether you need to see your doctor for diarrhoea or constipation.

The smell of flat poop

Flat poop does not have a specific smell. Sometimes, flat poop can occur alongside a strong, foul smell. Foul-smelling poop may be the result of a viral or bacterial infection, certain medications, or certain conditions. However, flat poop may also have a neutral smell. 

Diagnosis and treatment

Treating flat stools will depend on their cause. Your doctor may ask you to keep note of the foods you eat and the times when your stool changes. 

Lifestyle and dietary management are commonly used to treat constipation and IBS, and could also be used to treat flat stools. This may include:


Flat poop is characterised by thin, string-like stools. Flat poop may be caused by a variety of conditions, such as IBS, bowel cancer, and bowel polyps.

In addition, medication affecting the stomach's bacteria may cause bowel movement changes.

Sometimes, consuming certain foods or insufficient nutrients may cause flat poop. However, flat poop does not always have a known cause and may be harmless.

Treatment of frequent flat stools includes the modification of dietary factors and in some circumstances, medication for conditions causing flat poop.


  1. Suares NC, Ford AC. Systematic review: the effects of fibre in the management of chronic idiopathic constipation: Systematic review: effect of fibre in constipation. Alimentary Pharmacology & Therapeutics [Internet]. 2011 Apr [cited 2023 Apr 16];33(8):895–901. Available from: https://onlinelibrary.wiley.com/doi/10.1111/j.1365-2036.2011.04602.x
  2. Arnaud MJ. Mild dehydration: a risk factor of constipation? Eur J Clin Nutr [Internet]. 2003 Dec [cited 2023 Apr 16];57(2):S88–95. Available from: https://www.nature.com/articles/1601907
  3. Cuomo R, Andreozzi P, Zito FP, Passananti V, De Carlo G, Sarnelli G. Irritable bowel syndrome and food interaction. World J Gastroenterol [Internet]. 2014 Jul 21 [cited 2023 Apr 16];20(27):8837–45. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4112903/
  4. Linskens RK, Huijsdens XW, Savelkoul PHM, Vandenbroucke-Grauls CMJE, Meuwissen SGM. The bacterial flora in inflammatory bowel disease: current insights in pathogenesis and the influence of antibiotics and probiotics. Scandinavian Journal of Gastroenterology [Internet]. 2001 Jan 1 [cited 2023 Apr 16];36(234):29–40. Available from: https://doi.org/10.1080/003655201753265082
  5. Weitsman S, Celly S, Leite G, Mathur R, Sedighi R, Barlow GM, et al. Effects of proton pump inhibitors on the small bowel and stool microbiomes. Dig Dis Sci [Internet]. 2022 Jan 1 [cited 2023 Apr 16];67(1):224–32. Available from: https://doi.org/10.1007/s10620-021-06857-y
  6. James WB, Hume R. Action of metoclopramide on gastric emptying and small bowel transit time. Gut [Internet]. 1968 Apr [cited 2023 Apr 16];9(2):203–5. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1552556/
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

Get our health newsletter

Get daily health and wellness advice from our medical team.
Your privacy is important to us. Any information you provide to this website may be placed by us on our servers. If you do not agree do not provide the information.

Kristy Maskell

Master of Science – Nutrition and Dietetics, University of Hull
Bachelor of Science with Honours – Exercise and Health Science, University of Brighton

Kristy is a Dietetics master’s student which has allowed her to develop clinical knowledge of nutrition for a variety of populations. She is passionate about making evidence-based nutrition information accessible and loves to write this for everybody to read. Kristy looks forward to qualifying as a registered dietitian in the near future and having the opportunity to provide the best possible patient-centred care.

Leave a Reply

Your email address will not be published. Required fields are marked *

my.klarity.health presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
Klarity is a citizen-centric health data management platform that enables citizens to securely access, control and share their own health data. Klarity Health Library aims to provide clear and evidence-based health and wellness related informative articles. 
Klarity / Managed Self Ltd
Alum House
5 Alum Chine Road
Westbourne Bournemouth BH4 8DT
VAT Number: 362 5758 74
Company Number: 10696687

Phone Number:

 +44 20 3239 9818