What is IBS?

Irritable bowel syndrome (IBS) is a functional gastrointestinal (GI) disorder.1 It is a collection of symptoms, including recurring abdominal pain, bloating and changes in bowel movements.1-2 It is a disorder of the Gut-Brain Interaction (DGBIs,) which revolve around the gut-brain axis1-2.

A chronic condition, IBS needs to be managed long-term. IBS occurs without any visible signs of damage or disease to the digestive tract.2  The estimated global prevalence of IBS is thought to be around 11%.10 However, IBS widely thought to be under-reported. Many people have symptoms consistent with IBS, but do not consult a doctor and thus remain undiagnosed.

How is IBS diagnosed?

IBS is defined based on symptoms. An IBS diagnosis will be made by a gastroenterologist. 

Typically, a consultation will begin with a physical examination and medical history check. A doctor will ask questions to determine if there is a consistent history of symptoms that are characteristic of IBS. Lab tests routinely ordered by doctors include a complete blood count, erythrocyte sedimentation rate test, and fecal occult blood tests.7 

Since IBS symptoms can be similar to other diseases or disorders, there can be diagnostic errors, including celiac disease, inflammatory bowel disease, or colorectal cancer.4

Doctors use a set of symptom-based clinical guidelines to diagnose IBS. They include the Rome IV criteria.

These are based on abdominal pain, and changes in bowel habits.1 IBS diagnosis is made based on a report of bowel habits that need to have begun at least 6 months prior to diagnosis.

Other criteria that must be checked off 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 related to a bowel movement
  • Associated changes in stool frequency
  • Associated changes in stool form/appearance

These bowel habit changes also include symptoms that are 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

What are the Types of IBS?

There are three main types of IBS.1,5 The types of IBS are characterized according to chief complaints and bowel movement patterns:


IBS with constipation typically presents with hard/lumpy stools, and the occasional loose or watery stool.


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


IBS Mixed has both constipation and diarrhea. Bowel movements tend to vary between hard/lumpy stools and loose/watery stools.

There is also unclassified IBS (IBS-U.) Generally, other symptoms, such as abdominal pain and bloating, can also come into the mix – and is commonly seen for people with IBS-C.

What Causes IBS?

Currently, the exact cause of IBS is still not completely understood.1,6 IBS is considered multi-factorial, including gut physiology, environmental and psychological factors. Together, they can produce symptoms that lead to IBS:1-2,7-8

  • 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.
  • Stress and various psychological factors.

Furthermore, scientists have proposed certain mechanisms that seem to be involved in the pathogenesis of IBS, including: alterations in the gut-brain axis, visceral hypersensitivity, immune system activation, low-grade inflammation and the dysbiosis in the gut microbiota9

What are the Symptoms of IBS?

Generally, people with IBS report symptom complaints such as recurring periods of abdominal pain, that are often accompanied by changes in bowel habits. These include constipation, diarrhea, or a mix of both.

Abdominal pain is commonly described as a cramping sensation, which can sometimes dramatically increase in severity. Having a bowel movement can potentially offer some pain relief.4

Other gastrointestinal symptoms of IBS may include:4

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

IBS Treatment

Since there is current no cure for IBS, treatment actually relies on managing symptoms. Thus, the goal is to reduce overall symptoms and improve quality of life. 

Initially, management often focuses on resolving the dominant symptom – such as constipation or diarrhea. 

Nevertheless, there are several therapeutic approaches for managing IBS.7

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

Treating IBS relies on great communication and reporting between the IBS patient and their health care team. It’s important to follow-up on the agreed treatment plan, and report any changes as they arise. 


  1. Schmulson MJ, Drossman DA. What Is New in Rome IV. J Neurogastroenterol Motil. 2017;23(2):151–163. doi:10.5056/jnm16214
  2. Definition & Facts for Irritable Bowel Syndrome. National Institute of Diabetes and Digestive and Kidney Diseases. Available at https://www.niddk.nih.gov/health-information/digestive-diseases/irritable-bowel-syndrome/definition-facts#types. Accessed 4/14/20.
  3. Ford AC, Moayyedi P, Lacy BE, et al. American College of Gastroenterology monograph on the management of irritable bowel syndrome and chronic idiopathic constipation. Am J Gastroenterol. 2014;109 Suppl 1:S2-26; quiz S27.
  4. Wilkins T, Pepitone C, Alex B, Schade RR. Diagnosis and management of IBS in adults. Am Fam Physician. 2012;86:419-426.
  5. World Gastroenterology Organisation Global Guidelines. Irritable Bowel Syndrome: a Global Perspective. Available at: http://www.worldgastroenterology.org/UserFiles/file/guidelines/irritable-bowel-syndrome-english-2015.pdf. Accessed 4/14/20
  6. Camilleri M, Lasch K, Zhou W. Irritable bowel syndrome: methods, mechanisms, and pathophysiology. The confluence of increased permeability, inflammation, and pain in irritable bowel syndrome. Am J Physiol Gastrointest Liver Physiol. 2012;303:G775-G785.
  7. Sayuk GS, Gyawali CP. Irritable bowel syndrome: modern concepts and management options. Am J Med. 2015;128:817-827.
  8. Lacy BE, Chey WD, Lembo AJ. New and emerging treatment options for irritable bowel syndrome. Gastroenterol Hepatol (N Y). 2015;11(4 Suppl 2):1-19.
  9. Mari, Amir et al. “The Evolving Role of Gut Microbiota in the Management of Irritable Bowel Syndrome: An Overview of the Current Knowledge.” Journal of clinical medicine vol. 9,3 685. 4 Mar. 2020.
  10. Canavan C, West J, Card T. The epidemiology of irritable bowel syndrome. Clin Epidemiol. 2014;6:71‐80. Published 2014 Feb 4.