Irritable Bowel Syndrome (IBS)

What is irritable bowel syndrome?

Irritable Bowel Syndrome (IBS) is a common condition that affects the digestive system, impacting up to 3 in 10 people. IBS falls under a group of conditions known as Functional Gastrointestinal Disorders (FGIDs) or Disorders of Gut–Brain Interaction (DGBI). These disorders involve abnormal communication and coordination between the gut and the brain, leading to alterations in gut function and sensations

What are the symptoms of IBS?

Symptoms vary between individuals and can fluctuate over time. Common symptoms include:

  • Abdominal pain or cramping (often relieved by a bowel movement)

  • Bloating or excess wind

  • Changes in bowel habits, such as:

    • Diarrhoea

    • Constipation

    • Alternating diarrhoea and constipation

    • A sense of incomplete bowel emptying

    • Mucus in the stool

Symptoms are often worsened by stress, hormonal changes, or certain foods.

What causes IBS?

The exact cause is not fully understood, but several contributing factors have been identified:

  • Gut–brain axis dysfunction (altered communication between the gut and nervous system)

  • Changes in gut motility (how food moves through the digestive tract)

  • Visceral hypersensitivity (heightened sensitivity to gut sensations)

  • Imbalance in gut bacteria (dysbiosis)

  • Low-grade intestinal inflammation

  • Post-infectious IBS (following a gastrointestinal infection)

  • Stress and anxiety

  • Genetics (there is some evidence of hereditary susceptibility in certain individuals)

How is IBS diagnosed?

There is no single test for IBS, and it cannot be diagnosed by imaging, endoscopy, or blood tests alone, as no structural or biochemical abnormalities are found on standard tests.

A detailed history, physical examination, and basic investigations (e.g. blood tests, stool tests, coeliac screening) are usually sufficient for diagnosis. In some cases, additional tests such as gastroscopy or colonoscopy may be needed to rule out other diagnoses

How is IBS managed?

Management is individualised and typically involves a combination of:

  • Lifestyle and dietary management

  • Medical therapy

  • Psychological and behavioural interventions

1. Lifestyle and dietary management

  • Reduce or avoid common triggers, such as:

    • Gas-producing foods: onions, cabbage, Brussels sprouts, legumes

    • Lactose-containing foods: milk, ice cream, some yoghurts

    • Alcohol

    • Artificial sweeteners: aspartame, sorbitol, mannitol

  • A dietitian can work with you to find your triggers. They can also create a personalised diet plan which is balanced and sustainable

  • Low FODMAP diet: May be recommended under dietitian supervision. FODMAP is short for fermentable oligosaccharides, disaccharides, monosaccharides and polyols. These are the chemical names for different sugars that are poorly absorbed by the gut and can trigger IBS symptoms

  • Increase dietary fibre. Fibre-rich foods include fruit, vegetables, legumes, wholegrains, nuts, and seeds

  • Avoid excessive caffeine, alcohol, and highly processed foods

  • Engage in regular physical activity

  • Ensure adequate hydration and sleep

2. Medical therapy

Treatment depends on the predominant symptom:

  • Constipation: dietary modifications (i.e. increased fibre intake), increased fluids, fibre supplements, laxatives

  • Diarrhoea: loperamide, bile acid binders

  • Abdominal pain or bloating: antispasmodics, peppermint oil, or low-dose neuromodulators (e.g. tricyclic antidepressants or SSRIs)

3. Psychological and behavioural strategies

  • Stress management techniques

  • Cognitive behavioural therapy (CBT)

  • Gut-directed hypnotherapy

  • Mindfulness-based interventions, such as meditation and relaxation techniques

These approaches target the gut–brain connection and can significantly improve symptoms in some people.

What is the outlook for people with IBS?

IBS is a chronic but manageable condition. With the right combination of strategies, many people experience significant improvement in their symptoms and quality of life. IBS does not cause permanent damage to the bowel or increase the risk of colorectal cancer.