Irritable Bowel Syndrome

What Is Irritable Bowel Syndrome (IBS)?

Irritable bowel syndrome (IBS) is a chronic disorder that affects the normal functioning of the large intestines or colon. It is characterised by a group of symptoms, such as abdominal pain and changes in bowel movement. These symptoms often recur intermittently and may last for extended periods, ranging from several days to weeks or even months.

In Singapore, about 10% of people are diagnosed with IBS. This condition occurs most frequently among individuals in their 30s and 40s, with women being more affected than men.

Signs and Symptoms of IBS

Irritable bowel syndrome (IBS) presents a spectrum of symptoms that differ in intensity and duration from individual to individual. Common symptoms of IBS include:

Abdominal Pain or Discomfort

This pain typically presents as a cramp or dull ache in the lower abdomen, ranging from mild to severe. Typically, individuals experience relief after passing stool or gas.

Changes in Bowel Habits

Individuals with IBS may experience changes in bowel habits, including episodes of diarrhoea, constipation, or alternating between the two. In addition, there may be increased stool frequency.


People with IBS often experience feeling bloated, which is a sensation of fullness, tightness, or swelling in the abdominal area. This may worsen throughout the day and is commonly accompanied by excess gas and discomfort.

A Feeling of Incomplete Bowel Movements

Many individuals frequently describe a persistent sense of incomplete bowel movements following restroom use.

Changes in Stool Consistency

This can manifest as stools that are hard and lumpy, loose and watery, or a combination of both within a short period. The stool may also be mixed with a mucus-like substance that appears whitish.


Fatigue and lethargy are often reported by individuals with IBS, possibly due to the physical discomfort, disrupted sleep patterns, and emotional distress associated with the disorder.

Common Causes and Triggers for IBS

There is no exact cause for irritable bowel syndrome. However, several factors may contribute to the development and triggering of its symptoms, including:

Abnormal Gut Motility

This refers to the dysfunction of the digestive system, in which an individual's intestinal muscles may contract too fast or too slowly or cause food to move backwards.

Sensitive Nervous System

Nerve problems within the gastrointestinal tract can lead to discomfort as the belly expands due to gas or faecal matter. When the communication between the brain and the bowels is out of sync, the body may excessively respond to normal digestive fluctuations, resulting in symptoms like pain, diarrhoea, or constipation.

Environmental Factors

A variety of factors, including dietary choices, air quality, and lifestyle habits, can have a significant impact on gut health. Excessive smoking and alcohol consumption can also trigger IBS symptoms.


Individuals with stress, depression, and anxiety may cause gastrointestinal reactions and exacerbate IBS symptoms. This direct link is called the brain-gut connection and includes various physical factors, such as hormonal changes, as well as emotional or psychological stressors.


IBS can develop after an episode of severe diarrhoea caused by a bacterial or viral infection known as gastroenteritis. Similarly, IBS can be caused by an excessive amount of bacteria within the intestines (bacterial overgrowth).

Food Intolerance

This affects the GI tract and causes it to have difficulty breaking down certain foods. Food intolerance often results in gas, bloating, and diarrhoea, which are common symptoms of IBS.

How Is IBS Diagnosed?

A gastroenterologist can diagnose IBS through the following methods:

Medical History Review

The doctor will gather a comprehensive medical history, including symptoms, duration, triggers, family history of gastrointestinal diseases, and existing medical conditions.

Physical Examination

This is performed to inspect the abdomen and surrounding areas for physical signs and to eliminate other potential causes of the symptoms.

Symptom Assessment

The doctor diagnoses IBS using the Rome IV Criteria. These criteria require experiencing abdominal pain or discomfort at least once a week for three months. The pain should be linked to defecation or changes in stool frequency or consistency.

Furthermore, doctors may perform additional diagnostic tests to rule out other causes of symptoms or any underlying conditions. These include:

Stool Test

This test helps to check for signs of infection, inflammation, or other conditions that may be causing IBS symptoms. It can also identify the presence of blood in the stool.

Hydrogen Breath Test

This test detects certain digestive disorders, such as lactose and/or fructose intolerance or bacterial overgrowth, which can cause IBS symptoms.


This test examines the large intestine and rectum to look for signs of inflammation and polyps, or to detect more severe conditions, such as inflammatory bowel disease or colon cancer.


This test examines the upper digestive tract for any abnormalities, such as ulcers, inflammation, or coeliac disease, which could contribute to the symptoms.

Treatments for IBS

Treatments for IBS aim to alleviate symptoms and improve the patient's quality of life. These may include:

Dietary Changes

The doctor may suggest avoiding certain carbohydrates and foods that are poorly absorbed by the gut and can cause bloating, gas, and pain.

Lifestyle Modifications

Adopting a healthy lifestyle can mitigate the severity of IBS symptoms. These include regular physical activities, adequate rest, and managing stress levels effectively.


The doctor may prescribe medications specifically for IBS, such as antispasmodic medications to reduce intestinal contractions, antibiotics to address bacterial growth in the intestines, and probiotics to ease IBS symptoms.

Living With IBS

Living with IBS involves adopting coping strategies such as identifying and avoiding food triggers, managing stress with techniques like meditation, and staying active for regular bowel movements. Keeping a symptom diary can also help track which foods or activities exacerbate IBS symptoms.

Moreover, having regular follow-ups with a gastroenterologist is crucial for managing IBS. These visits can help monitor the condition, make necessary adjustments to treatment plans, and provide support. By actively managing symptoms and seeking support, patients can improve their quality of life.

Frequently Asked Questions (FAQs)

What’s the difference between IBS and IBD?

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Does IBS increase the risk of cancer?

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How can I manage an IBS flare-up?

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Meet Our IBS Doctor

Dr Kieron Lim

MBBS, University of LondonMember, Royal College of Physicians (UK)Fellow, Academy of Medicine (Gastroenterology) SingaporeFellow, Royal College of Physicians (Edinburgh)

Dr Kieron Lim is a senior consultant gastroenterologist in Singapore who specialises in treating patients with digestive conditions, including irritable bowel syndrome (IBS). With two decades of specialist experience from Singapore, the United States and the United Kingdom, he uses comprehensive medical treatments and advanced endoscopic procedures to help his patients achieve an improved quality of life.