Flat Poop: Causes, Diets, Diseases & Remedies

Introduction

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.

Causes

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. 

Conditions

• A condition known as irritable bowel syndrome (IBS) affects the digestive system and can cause abnormal bowel movements. Those with IBS often have different stool types, which vary from very large stools to pencil-thin stools
• Bowel cancer will cause a change in your bowel habits. This may look different for everybody, and symptoms vary from constipation to needing to poop more often. In some cases, bowel cancer may cause a bowel obstruction. A bowel obstruction is a medical emergency and is characterised by an inability to pass wind, bloating, sickness, and abdominal pain
• An enlarged prostate could also cause flat poop. The scientific term for this condition is known as benign prostate enlargement (BPE) and this condition affects the function of the bladder among males, causing bladder difficulties. However, in some cases, BPE impacts bowel movements and causes flat poop
• Small growths within the lining of your large intestine known as bowel polyps will have a significant impact on how your stools look. Bowel polyps can cause mucus or blood in your poop as well as diarrhoea and constipation. In addition, some of your stools may have a flat appearance

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

Food

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

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:

• Antibiotics - antibiotics destroy bacteria within the gut. However, some of that destroyed bacteria is beneficial to the body. The brief alterations in bacteria can lead to temporary changes in bowel habits and stool appearance, causing flat poop⁴
• Proton pump inhibitors - this type of medication is usually prescribed to those suffering from acid reflux or gastroesophageal reflux disease (GERD). The mechanism of action for this type of medication includes stopping the production of stomach acid,  leading to different bacterial flora within the gut.⁵
• Medications which affect stomach emptying time, like metoclopramide, are designed to promote frequent bowel movements.⁶ When stools are passed more often than usual, your stool shape and size might change. 

Symptoms

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:

• Drinking enough fluids to reduce constipation and make stools easier to pass
• Increasing the amount of fibre in your diet. Fibre is found in many fruits and vegetables as well as whole-grain foods
• Being more physically active. Physical activity provides your body with a wide array of benefits, and will also help to quicken your digestion
• Reducing the amount of stress in your everyday life can help to improve your mental health and your stool habits. Stress-relieving techniques may include meditating, journaling, yoga, and deep breathing

Summary

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.