What to know about irritable bowel syndrome

Irritable bowel syndrome is more than just an upset tummy; it is a disruption of intestinal function. In this article, a consultant gastroenterologist explains the signs of IBS, and the approaches to treatment.

What is IBS?

Irritable bowel syndrome (IBS) is a common condition that affects the gastrointestinal tract (digestive system). It is characterised by a group of symptoms that occur together to disrupt normal bowel habits and can indeed be quite uncomfortable for patients. Unlike inflammatory conditions such as Crohn’s disease or ulcerative colitis, IBS does not cause visible damage to the gut on standard investigations.

The exact cause of IBS is not fully understood, but several factors are thought to play a role. These include abnormal contractions of the gut muscles, increased sensitivity to gut sensations, changes in gut bacteria, and disturbances following infections or periods of stress. In some people, symptoms begin after a bout of food poisoning or gastroenteritis – a phenomenon known as post-infectious IBS. Others may notice symptoms worsening during periods of psychological stress or anxiety, indicating a strong link between the gut and the brain.

Signs of IBS

The main symptoms of IBS include abdominal pain or discomfort, bloating, and a change in bowel habits such as diarrhoea, constipation, or both. These symptoms often fluctuate in intensity and can be triggered by certain foods, hormonal changes (especially around menstruation), or emotional stress.

Diagnosis is based largely on clinical symptoms, which include recurrent abdominal pain at least one day per week in the last three months, associated with defecation or a change in bowel habits. There is no single test for IBS, but it is important to exclude other conditions that may mimic it. Blood tests, stool studies, and sometimes imaging like ultrasounds or investigations like endoscopy may be used to rule out coeliac disease, inflammatory bowel disease, or bowel cancer, particularly in older patients or those with ‘red flag’ symptoms like unexplained weight loss, rectal bleeding or anaemia.

Differences between IBS and IBD

Though they sound similar, IBS and IBD (inflammatory bowel disease) are fundamentally different. IBS is a functional disorder, meaning it is related to how the bowel works, not to structural damage or inflammation. IBD, which includes Crohn’s disease and ulcerative colitis, involves chronic inflammation that can be seen on scans and during colonoscopy, and can lead to serious complications such as strictures, fistulas, and malnutrition.

IBD is usually diagnosed through a combination of blood tests, faecal calprotectin (a marker of intestinal inflammation), imaging, and biopsy. In contrast, IBS does not show signs of inflammation or damage on these investigations. It is important to make the distinction clearly, as treatment and long-term outlook differ significantly.

What are the risks of IBS?

IBS is not life-threatening and does not increase the risk of bowel cancer or other serious gastrointestinal diseases. However, it can have a significant impact on quality of life. Persistent symptoms can lead to loss of work days, social withdrawal, poor sleep, and mental health difficulties such as anxiety or depression. It’s important not to dismiss IBS as a minor issue, as for many patients it is debilitating and deeply frustrating, disrupting daily life and preventing patients from engaging with social activities, sports, and important tasks.

Treatment for IBS

There is no one-size-fits-all treatment for IBS, and management focuses on relieving symptoms and improving quality of life. Dietary modifications are often the first step. Many patients benefit from increasing dietary fibre (particularly soluble fibre) or following a low FODMAP diet, which reduces certain fermentable carbohydrates known to trigger symptoms. However, such diets should ideally be followed under the guidance of a dietitian.

Medications may include antispasmodics for cramping, laxatives for constipation, or anti-diarrhoeal agents. In some cases, low-dose antidepressants can help with pain and gut-brain regulation, even if the patient is not depressed. Psychological therapies such as cognitive behavioural therapy (CBT) and gut-directed hypnotherapy have also shown good results, particularly in patients with significant anxiety or stress.