Irritable bowel syndrome (IBS) poop classifications are part of the diagnostic evaluation for this condition. They range from constipation to diarrhea and anywhere in between.

IBS is a functional gastrointestinal disorder (FGID), where there is disruption in communication between the brain and digestive system. It leads to abdominal pain, bowel movement changes, gas, and bloating.

The American College of Gastroenterology states 10–15% of people in the United States live with IBS. It is most commonly seen in women but can occur in anyone.

Stool formation is an important consideration in IBS. It helps determine the correct diagnosis and which medications doctors prescribe to treat bowel patterns.

This article explores IBS poop classifications and their defining characteristics.

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Stool’s appearance in IBS indicates what is happening in the body.

For some people, the altered communication between the brain and the gut in IBS causes nutrients to move too quickly through the digestive tract, resulting in diarrhea.

The opposite can also be true. Nutrients may move too slowly, resulting in constipation.

Doctors classify IBS based on these bowel patterns. The Rome IV criteria is a set of IBS-specific clinical guidelines that outlines stool type and frequency.

IBS with diarrhea more than 25% of the time is called IBS-D.

IBS with constipation more than 25% of the time is called IBS-C.

Doctors call mixed bowel patterns IBS-M, alternating IBS, or IBS-A.

Learn about 10 signs and symptoms of IBS.

The characteristics of IBS-C are abdominal pain, discomfort, and bloating.

With this type of IBS, infrequent bowel movements and straining are common. Some people report the sensation of a blockage or of not having emptied the bowels after using the bathroom.

Abdominal discomfort in IBS-C tends to improve after a bowel movement, but passing stool may occur less than several times a week.

What might poop look like?

IBS-C poop may be hard, dry, lumpy, and difficult to pass. It may be darker in color from sitting in the bowels longer.

IBS-D also presents with bloating and abdominal pain or discomfort. The urge to pass stool is frequent and occurs during waking hours. Stress or eating certain foods may trigger IBS-D.

Many people also experience nongastrointestinal symptoms with this form of IBS, including:

  • menstrual changes
  • increased urination output or urgency
  • sexual function changes
  • transient bodily aches and pains

IBS-D does not commonly cause urgency to poop while sleeping. If this happens, another medical condition could be present.

What might poop look like?

IBS-D poop can be extremely loose, runny, or liquid and may contain a significant amount of mucous.

Diarrhea may be green from bile passing through the large intestine too quickly.

Learn about coping with IBS.

In addition to the Rome IV criteria, stool is evaluated in a clinical setting using the Bristol Stool Form Scale (BSFS), a diagnostic tool that assigns a numerical value to stool formations ranging from 1–7.

The BSFS stool types are:

  • Type 1: Difficult to pass, separated, hard lumps — likened to nuts.
  • Type 2: Lumpy, sausage-shaped.
  • Type 3: Sausage-shaped with surface cracks.
  • Type 4: Smooth and soft, snake-like or sausage-shaped.
  • Type 5: Easily passed, soft blobs with clearly defined edges.
  • Type 6: Mushy, fluffy pieces with ragged edges.
  • Type 7: Entirely liquid, no solid pieces.

Under the BSFS, types 3, 4, and 5 are normal formations.

However, what makes poop “normal” can vary between people. Overall, it should:

  • remain consistent in frequency
  • pass without pain
  • be soft or firm in texture

Typical stool is brown due to bile and bilirubin, a byproduct of red blood cell breakdown in the intestine. While diet can affect stool color, major changes can indicate underlying medical conditions.

Some people have bowel movements several times a day, while others only pass stool several times a week. Less than this can indicate constipation, while a higher frequency may indicate diarrhea.

The presence of volatile organic compounds (VOCs) in stool makes it natural for poop to have a strong odor. Its pungent smell results from microbial activity as components of the stool break down.

As with color, stool odor can vary, but unusual changes could indicate health concerns.

Learn more about types of poop.

No amount of blood in poop is routine, but it is not always a cause for alarm.

A person may notice trace amounts of blood on toilet paper after wiping. This can be from minor tears in the lining of the anus from passing hard stool.

Minor irritation like this can be self-limiting and does not necessarily need medical intervention.

However, seeing blood in stool indicates bleeding somewhere in the gastrointestinal (GI) tract.

Rectal bleeding, known as hematochezia, is associated with visible blood in or around the stool. It is typically linked to lower GI tract issues such as:

Upper GI tract bleeding may be less obvious. Blood in the stool from higher in the GI system commonly presents as black, tarry bowel movements.

Occasionally, small amounts of blood from the upper GI tract pass through the intestines too quickly to change color, appearing as rectal bleeding.

Find out whether food can cause bloody stools.

Recurrent bouts of diarrhea or constipation, accompanied by pain, discomfort, and bloating, may indicate IBS.

Experiencing changes in stool frequency, consistency, color, or odor can also indicate underlying medical health concerns. Even small amounts of blood in the stool may point to serious conditions such as colon cancer. If a person experiences these changes, they must consult a doctor.

IBS is manageable but not curable.

Medications can help regulate intestinal movement speed, bowel movement frequency, and the texture of IBS poop. Doctors also recommend avoiding trigger foods and managing stress.

Learn more about IBS diets.

The characteristics of poop indicate what may be happening inside the body. Hard, difficult-to-pass stool is associated with IBS-C, while frequent, loose stool is characteristic of IBS-D.

Typical poop should be consistent in frequency, pass without pain, and be soft or firm. Blood in the stool may come from tears in the anus or indicate a more serious health condition.

Anyone with concerns about their stool should talk with a doctor.

There is no cure for IBS, but medications and lifestyle adjustments can help improve symptoms.