IBS: Symptoms, Causes, Types, Diagnosis and Treatment in South Africa

Irritable bowel syndrome (IBS) is a common condition in which people experience recurrent abdominal pain or discomfort together with changes in how often they pass stool and what the stool looks like. The bowel itself is structurally normal, but the way it functions and how the gut and brain communicate with each other is altered. Symptoms often come and go over months or years and can affect daily comfort without causing lasting damage to the intestine.

Common experiences that occur with IBS

People who meet the usual description of IBS often report a combination of pain and altered bowel habits. The pain is typically felt in the lower abdomen and may ease, worsen, or stay the same after a bowel movement. Other experiences that may occur include a feeling of incomplete emptying, visible abdominal bloating or tightness, and the passage of mucus with stool. These are examples of what many people notice rather than a checklist that confirms the condition.

• Crampy or aching abdominal pain that is linked in time to bowel movements
• Alternating periods of looser stools and harder stools, or a predominant pattern of one or the other
• Abdominal bloating or a sensation of fullness that varies through the day
• Urgency or a feeling that the bowel has not fully emptied
• Extra gas or flatulence

Some people also notice tiredness, nausea, or discomfort in the back or pelvis when bowel symptoms are more active. Symptoms are frequently more noticeable during times of increased stress, and in women they may vary with the menstrual cycle.

Factors that may contribute to IBS symptoms

No single cause has been identified. Current understanding describes IBS as a disorder of gut-brain interaction in which several factors can influence how the intestine moves, how sensitive it is to normal stretch or gas, and how signals travel between the gut and the brain. The British Society of Gastroenterology notes that diet, stress, prior infection, and individual responses to symptoms can all play a role in this interaction.

• Changes in the speed or coordination of intestinal muscle contractions
• Heightened sensitivity of the gut to normal amounts of gas or stool
• Shifts in the balance of bacteria living in the intestine
• Dietary patterns that increase gas or osmotic load in the bowel
• Stress, anxiety, or other psychological factors that amplify gut signals
• A previous episode of gastroenteritis in some people

These factors do not explain every case, and many people with IBS have more than one contributing influence at the same time. Identifying personal triggers usually requires careful observation of diet, routines, and stress rather than a single test.

Patterns of bowel habit used to describe IBS

Clinicians often describe IBS according to the main stool pattern that is present on days when symptoms occur. This description helps guide the choice of first approaches rather than indicating separate diseases.

In constipation-predominant IBS the majority of stools tend to be hard or lumpy and the person may strain or feel incomplete emptying. In diarrhoea-predominant IBS loose or watery stools are more common and urgency may be prominent. Mixed IBS involves both hard and loose stools on different days, while an unclassified pattern does not fit neatly into the other groups. Details of managing the constipation pattern are covered separately on the page about IBS and constipation.

The pattern can shift over time for some people, so the label is mainly useful for choosing symptom-focused measures rather than a fixed category.

How a clinician recognises IBS

According to the National Department of Health primary healthcare guidelines, IBS is defined as recurrent abdominal pain occurring on average at least one day per week in the last three months and associated with two or more of the following: the pain is related to defecation, there is a change in stool frequency, or there is a change in stool form. The history is typically protracted and intermittent and is often more pronounced when stress is present. It is regarded as a functional disorder and is most commonly seen in women between the ages of 15 and 45 years.

In practice, a clinician (usually a general practitioner or a clinician working at a primary healthcare clinic) takes a detailed history and performs a focused examination. Limited blood and stool tests are often arranged to look for other explanations such as coeliac disease or inflammation. Further tests such as colonoscopy are not required for every person who fits the symptom pattern and has no alarm features. The British Society of Gastroenterology supports making a positive diagnosis based on the characteristic symptoms once simple tests are normal and red-flag features are absent.

Referral to a gastroenterologist is considered when symptoms are severe, do not respond to initial measures, or when features such as rectal bleeding, unexplained weight loss, age over 50 at onset, or findings suggestive of inflammatory bowel disease are present. These are the referral points listed in the National Department of Health guidance.

Approaches used to reduce the impact of symptoms

Management focuses on reducing the frequency and intensity of symptoms so that daily activities are less disrupted. The National Department of Health guidelines advise reassuring the person that the condition is not life-threatening while acknowledging its effect on quality of life, and they recommend dietary advice from a dietician. High-fibre or bran diets may be tried when constipation is the main problem, although they do not reliably improve all symptoms and can temporarily increase gas and bloating.

International guidance from the British Society of Gastroenterology and the American College of Gastroenterology supports regular physical activity, first-line dietary advice, and a trial of soluble fibre such as ispaghula for global symptoms. Insoluble fibre is generally avoided because it can worsen discomfort. Short-term use of anti-spasmodics, anti-diarrhoeals, or laxatives may be considered according to the predominant symptom; the specific choice and duration are decided by the treating clinician.

Psychological approaches that address the gut-brain interaction can be helpful for some people. Cognitive behavioural therapy is one option that has been studied for symptom reduction and is discussed further on the page about CBT for IBS. Women who notice a clear worsening around menstruation may find additional context on the page covering IBS and periods.

In a minority of people, symptoms that closely resemble IBS may later be found to relate to small intestinal bacterial overgrowth. Distinguishing the two is covered on the page about IBS versus SIBO.

When further medical assessment is advisable

Most people with a typical IBS pattern and no alarm features can be managed in primary care. Prompt review at a clinic or with a general practitioner is appropriate when symptoms change suddenly, when new rectal bleeding or black stools appear, when there is unintentional weight loss, or when pain becomes severe and persistent. The National Department of Health lists blood or mucus in the stool, weight loss, age over 50 at the start of symptoms, and features suggestive of inflammatory bowel disease as reasons for referral. Sudden severe abdominal pain, vomiting blood, or confusion warrant urgent evaluation at an emergency unit rather than routine clinic attendance.

A clinician considers the full history, examination findings, and any test results before deciding whether the pattern is consistent with IBS or whether another explanation needs investigation. Individual responses to dietary changes, fibre, or other measures vary, so adjustments are made over time with professional guidance.