What Is IBS?

Irritable bowel syndrome (IBS) is a functional gastrointestinal (GI) disorder.1 It is a group of symptoms which include recurring stomach pain and changes in bowel movements.1-2 The condition is defined as a disorder of gut-brain interaction (DGBI). They are related to issues with how the brain and gut interact.1-2

ROME IV is a set of clinical guidelines your doctor will use to diagnose IBS. It is based on symptoms of stomach pain associated with changes in bowel habits.1 A diagnosis of IBS is made based on a report of bowel habits that start at least 6 months prior to diagnosis. Other criteria include recurrent stomach pain for at least 1 day per week during the 3 months before diagnosis combined with at least two of the following:1

  • Pain increased or unchanged related to a bowel movement
  • Associated with a change in stool frequency
  • Associated with a change in stool form or appearance

These changes in bowel habits include symptoms predominantly related to either diarrhea or constipation. It also includes people with a mix of bowel movements that include both loose and hard stools.1,4

IBS occurs without any visible signs of damage or disease to the digestive tract.2 The condition is unlikely to increase the risk for the development of cancer or inflammatory bowel disease.5 The estimated prevalence of IBS in North America ranges from 10 percent to 15 percent, occurring commonly in adolescents and adults.2 However, IBS is thought to be under-reported. Many people with symptoms consistent with IBS do not consult a doctor and therefore go undiagnosed.5

Types of IBS

There are three main types of IBS.1,5 The types of IBS are described by bowel movement patterns:


IBS with constipation has typically hard or lumpy stools with the occasional loose or watery stool.


IBS with diarrhea has typically loose or watery stools with the occasional hard or lumpy stool.


IBS Mixed has constipation and diarrhea. Bowel movements may vary between hard or lumpy stools and loose or watery stools.

What causes IBS?

The exact cause of IBS is still not completely understood.1,6 IBS is thought to be caused by multiple factors including psychosocial, environmental, and gut physiology. These factors together can produce symptoms that can result in IBS:1-2,7-8

  • Microenvironmental factors including a genetic predisposition to abnormalities in the gut bacteria, diet, and infections.
  • Gut physiology can change over time. Inflammation, the movement of food and waste through the gut, and the way the body responds to gut disturbances can contribute to the development of IBS.
  • Biopsychosocial factors may include stress and various psychological factors.

Symptoms of IBS

Typical symptom complaints of IBS are recurring periods of stomach pain accompanied by changes in bowel habits. These include constipation, diarrhea, or a mix of constipation and diarrhea. Stomach pain is commonly described as a cramping sensation, which may sometimes be severe. Having a bowel movement may relieve some of the pain.4

Other gastrointestinal symptoms of IBS may include:4

  • Feeling a lump in the throat
  • Belching
  • Acid reflux
  • Difficulty swallowing (dysphagia)
  • Feeling full soon after eating
  • Intermittent indigestion (dyspepsia)
  • Nausea
  • Chest pain not associated with heart disease
  • Abdominal bloating and flatulence (gassiness)

Diagnosing IBS

IBS is defined by symptoms. An IBS diagnosis is made by a gastroenterologist. The American College of Gastroenterology, which simply states IBS as abdominal pain with disordered bowel movements. However, this definition still has not yet been validated.6

Symptom-based guidelines are used to diagnose IBS. They include the Manning criteria and the Rome IV criteria. The Rome IV criteria were updated in 2016 and include a standardized, broader definition of IBS that is based on GI function.1

An IBS diagnosis begins with a physical examination and a thorough about medical history. A doctor will ask questions to determine if there is a consistent history of symptoms characteristic of IBS. Routinely ordered lab tests include a complete blood count (CBC), erythrocyte sedimentation rate test, and fecal occult blood tests.7 IBS symptoms can be similar to other diseases or disorders. This may result in mistaken diagnoses including celiac disease, inflammatory bowel disease, or colorectal cancer.4

IBS treatment and management

The goal of IBS treatment is to reduce overall symptoms; to improve both gastrointestinal comfort and quality of life. Since there is presently no cure for IBS, the initial management strategy is typically directed to addressing the overall severity of symptoms and resolving the dominant symptom. There are several therapeutic approaches to managing IBS.7

  • Diet
  • Exercise
  • Stress management
  • Probiotics
  • Fiber supplements and laxatives
  • Medications
  • Alternative or complementary medicine

Treating IBS is based on good communication and reporting between the patient and the health care team. Following the agreed-upon treatment protocol and reporting changes as they develop.

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Written by: Linda Saxl Minton | Last reviewed: April 2020