What is Irritable Bowel Syndrome?


Irritable bowel syndrome (IBS) is one of the most common gastrointestinal (GI) disorders that affects the large intestine (colon). It is a chronic condition that can cause discomfort and distress but does not cause permanent damage to the colon or increase the risk of colorectal cancer.1

Irritable bowel syndrome is characterised by a group of symptoms that can vary in intensity and duration from person to person, including abdominal pain, bloating, cramping, diarrhoea, constipation, or alternating periods of both diarrhoea and constipation. Other symptoms may include gas, mucus in the stool, and a feeling of incomplete bowel emptying.2

The exact cause of irritable bowel syndrome remains unknown. However, several factors have been identified as possible contributors to the development of the condition. These include abnormalities in the normal functioning of the digestive system, changes in the balance of gut bacteria, and alterations in the communication between the brain and the gut. Despite these associations, the underlying cause of irritable bowel syndrome remains unclear and is likely to be multifactorial, involving a complex interplay of genetic, environmental, and lifestyle factors. 2

Globally, irritable bowel syndrome is estimated to affect 10% of the general population, however, this might vary from country to country.1 Although there is no cure for IBS, the symptoms can be managed through changes in diet and lifestyle, medications, and stress reduction techniques. 

Causes of irritable bowel syndrome

The cause of irritable bowel syndrome is not fully understood, but there are several factors that have been linked to the development of the condition. These include:3

Environmental triggers:

  • Early life stressors such as abuse, and psychosocial stressors
  • Food intolerance
  • Antibiotics
  • Enteric (intestinal) infection

Changes in gut microbiota (normal gut bacteria) triggers:

  • Altered pain perception
  • Altered brain-gut interaction
  • Dysbiosis4 (imbalance in normal gut bacteria)
  • Increased intestinal permeability
  • Increased gut mucosal immune activation

In addition, some studies have suggested that genetic factors may play a role in the development of IBS.5 However, the exact genes involved and how they contribute to the condition are not fully known.

Signs and symptoms of irritable bowel syndrome

Irritable bowel syndrome can cause a range of signs and symptoms that can vary in intensity and duration from person to person. Some of the most common signs and symptoms of IBS include:2

  • Abdominal pain or discomfort: This can range from mild to severe and is often located in the lower abdomen
  • Bloating: This is a feeling of fullness or swelling in the abdomen, which may be accompanied by gas
  • Diarrhoea: This can be defined as loose or watery stools, which may be accompanied by urgency or a feeling of incomplete bowel emptying
  • Constipation: This refers to difficulty passing stools or infrequent bowel movements
  • Mucus in the stool: This is a common symptom of IBS and is caused by inflammation in the colon
  •  Nausea: This can be a symptom of IBS, especially during periods of abdominal pain

According to the NIDDK, people assigned female at birth (AFAB) with IBS may experience more symptoms during their menstrual periods. Although IBS can be painful, it is not known to cause other health problems or damage the digestive tract. A diagnosis of irritable bowel syndrome is typically made based on a pattern of symptoms observed over time. Irritable bowel syndrome is a chronic condition, meaning that it can last for years, but symptoms may vary in frequency and intensity.

Management and treatment for irritable bowel syndrome

There is no cure for irritable bowel syndrome, but there are several strategies that can be used to manage and treat the condition. Some of these strategies include:

  • Dietary changes: Avoiding certain foods that trigger IBS symptoms, such as caffeine, alcohol, and fatty or spicy foods, can help to manage the condition
  • Fibre supplements: Adding fibre to the diet can help to regulate bowel movements and relieve constipation, but it is important to start with a low dose and gradually increase it to avoid worsening symptoms
  • Medications: Several medications can be used to manage IBS symptoms, including antispasmodics to relieve abdominal pain and cramping, laxatives to relieve constipation, and antidepressants to help manage mood and anxiety
  • Stress reduction: Stress can exacerbate IBS symptoms, so stress-reduction techniques such as exercise, meditation, and deep breathing can help to manage the condition
  • Probiotics: Probiotics are beneficial bacteria that can help to restore the balance of gut microbiota and relieve IBS symptoms

It is important to note that the management and treatment of irritable bowel syndrome will vary from person to person, and it is important to work with a healthcare provider to develop an individualised treatment plan.

Recommended medication for irritable bowel syndrome

  • Antidiarrheals medications such as Loperamide are recommended to help prevent diarrhoea
  • Laxatives to prevent constipation
  • Fibre supplements
  • Serotonin agents influence gastrointestinal motility and visceral sensation
  • Antispasmodics help relax the muscles of the gut
  • Probiotics


How is irritable bowel syndrome diagnosed?

Irritable bowel syndrome is typically diagnosed through a combination of physical exams, medical history, and diagnostic tests. These tests may include blood tests, stool tests, a colonoscopy, or imaging studies. A doctor may also use the Rome IV criteria, a set of symptom-based guidelines, to help diagnose IBS.3

How can I prevent irritable bowel syndrome?

Unfortunately, there is no known way to prevent irritable bowel syndrome. However, maintaining a healthy diet, staying hydrated, managing stress, and getting regular exercise may help reduce symptoms or prevent them from worsening.

What are the types of irritable bowel syndrome?

There are three types of irritable bowel syndrome (IBS):3

  • IBS with constipation (IBS-C): IBS that involves constipation is characterised by having hard or lumpy stools in more than 25% of bowel movements, while loose or watery stools are present in less than 25% of bowel movements
  • IBS with diarrhoea (IBS-D): IBS that involves diarrhoea is characterised by having loose or watery stools in more than 25% of bowel movements, while hard or lumpy stools are present in less than 25% of bowel movements
  • IBS with mixed bowel habits (IBS-M): Mixed IBS is characterised by having both hard or lumpy stools and loose or watery stools

Who is at risk of irritable bowel syndrome?

Irritable bowel syndrome is more common in people AFAB, with up to twice the likelihood of developing the condition compared to people assigned male at birth (AMAB). Individuals below 50 years of age are also more susceptible to IBS than those over 50 years of age. Having a family member with irritable bowel syndrome, a history of childhood abuse, or exposure to stressful life events, and having a severe infection in the digestive tract are some of the factors that can increase the risk of developing IBS.2

How common is irritable bowel syndrome?

Irritable bowel syndrome is a common condition that affects an estimated 10-15% of the world's population. It is the most common functional gastrointestinal disorder seen in primary care.6

When should I see a doctor?

You should see a doctor if you are experiencing persistent or severe symptoms of irritable bowel syndrome, or if your symptoms are interfering with your daily life. Other reasons to seek medical attention may include unintended weight loss, rectal bleeding, or symptoms that worsen over time.


Irritable bowel syndrome (IBS) is a common gastrointestinal disorder that affects an estimated 10-15% of the world's population. The causes of IBS are believed to be related to several factors including changes in gut microbiota, abnormalities in the way the digestive system works, and alterations in the brain-gut axis. Certain problems, including bacterial infections, food intolerances or sensitivities, and mental health disorders, have also been associated with IBS. IBS can be characterised by various symptoms, including abdominal pain, bloating, diarrhoea, and constipation. People AFAB with IBS may experience more symptoms during their menstrual periods. IBS can be a chronic disorder that lasts for years, but the symptoms may come and go.

There is no treatment to cure IBS completely, but various management and treatment strategies can help alleviate symptoms. These may include dietary changes, such as avoiding certain foods that trigger symptoms, increasing fibre intake, and taking probiotics. Medications, including laxatives, antispasmodics, and antidepressants, may also be used to manage symptoms. Additionally, stress management techniques, such as meditation and cognitive-behavioural therapy, may be helpful for some individuals.


  1. Moayyedi P, Andrews CN, MacQueen G, Korownyk C, Marsiglio M, Graff L, et al. Canadian association of gastroenterology clinical practice guideline for the management of irritable bowel syndrome(Ibs). Journal of the Canadian Association of Gastroenterology. 2019 Feb 11;2(1):6–29. Available from: https://academic.oup.com/jcag/article/2/1/6/5290372
  2. Enck P, Aziz Q, Barbara G, Farmer AD, Fukudo S, Mayer EA, et al. Irritable bowel syndrome. Nat Rev Dis Primers. 2016 Mar 24;2:16014. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5001845/
  3. Chey WD, Kurlander J, Eswaran S. Irritable bowel syndrome: a clinical review. JAMA. 2015 Mar 3;313(9):949. Available from: http://jama.jamanetwork.com/article.aspx?doi=10.1001/jama.2015.0954
  4. DeGruttola AK, Low D, Mizoguchi A, Mizoguchi E. Current understanding of dysbiosis in disease in human and animal models. Inflamm Bowel Dis. 2016 May;22(5):1137–50. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4838534/
  5. Card T, Canavan C, West J. The epidemiology of irritable bowel syndrome. CLEP. 2014 Feb;71. Available from: http://www.dovepress.com/the-epidemiology-of-irritable-bowel-syndrome-peer-reviewed-article-CLEP
  6. Saito YA. The role of genetics in ibs. Gastroenterology Clinics of North America. 2011 Mar;40(1):45–67. Available from: https://linkinghub.elsevier.com/retrieve/pii/S0889855310001354
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.

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Aisha Mohamed

BSc (Hons) Nursing Studies (Adult), Nursing, Glasgow Caledonian University

Aisha Mohamed is a Registered Nurse (RN) with a Bachelor of Science degree in Nursing. With a strong academic background, Aisha has developed a comprehensive understanding of the medical field and has a deep commitment to providing quality patient care. Aisha currently works in clinical research specialty as she is passionate about improving community health through scientific medical research. These skills translate to her writing, as she is able to convey important medical information in a way that is easy for readers to understand.

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