What Is Irritable Bowel Syndrome?

Irritable Bowel Syndrome (IBS) is a functional gastrointestinal disorder — meaning the digestive system looks structurally normal but doesn't work as it should. It's characterised by a cluster of symptoms including abdominal pain, bloating, and changes in bowel habits, and it follows a chronic, relapsing pattern.

IBS is not the same as inflammatory bowel disease (IBD), which includes Crohn's disease and ulcerative colitis. IBS involves no structural damage to the bowel and is not associated with increased risk of bowel cancer.

Hallmark Symptoms of IBS

IBS presents differently in different people, but the defining features include:

  • Abdominal pain or cramping — typically relieved (at least partially) by passing a bowel motion
  • Bloating and distension — often worsening throughout the day
  • Altered bowel habits — diarrhoea (IBS-D), constipation (IBS-C), or alternating between both (IBS-M)
  • Urgency — sudden, hard-to-ignore need to use the toilet
  • Mucus in stools
  • Feeling of incomplete emptying after a bowel movement

Symptoms often worsen during periods of stress or after eating, and many people notice a pattern of flares and remissions.

What Triggers IBS Flare-Ups?

Identifying personal triggers is one of the most effective ways to manage IBS. Common triggers include:

Dietary Triggers

  • High-FODMAP foods — fermentable carbohydrates found in onions, garlic, wheat, apples, and legumes
  • Fatty or fried foods
  • Caffeine and alcohol
  • Carbonated drinks
  • Dairy products (in those with lactose sensitivity)
  • Large meal portions eaten quickly

Non-Dietary Triggers

  • Psychological stress and anxiety — the gut-brain axis means emotional states directly affect gut function
  • Hormonal changes — many women notice symptom changes linked to their menstrual cycle
  • Gut infections — post-infectious IBS can develop after gastroenteritis
  • Disrupted sleep

Evidence-Based Approaches to Managing IBS

The Low-FODMAP Diet

The low-FODMAP diet, developed by researchers at Monash University, has strong evidence for reducing IBS symptoms. It involves a structured elimination phase, followed by reintroduction to identify specific intolerances. This diet should ideally be guided by a registered dietitian to ensure nutritional adequacy.

Soluble Fibre Intake

Soluble fibre (found in oats, psyllium husk, and carrots) can help regulate bowel habits for both IBS-D and IBS-C. In contrast, insoluble fibre (found in bran) may worsen symptoms for some people — so type of fibre matters.

Stress Management

Gut-directed hypnotherapy and CBT have good evidence for improving IBS outcomes, particularly when psychological stress is a significant driver. Mindfulness-based approaches can also reduce gut hypersensitivity over time.

Medications

Depending on the dominant symptom pattern, a GP may suggest:

  • Antispasmodics (e.g., peppermint oil, hyoscine) for cramping
  • Laxatives for IBS-C
  • Loperamide for IBS-D
  • Low-dose antidepressants — which also modulate gut pain signals

When to See a Doctor

IBS symptoms overlap with more serious conditions. See a GP promptly if you notice:

  • Blood in your stool
  • Unintentional weight loss
  • Symptoms that wake you from sleep
  • New symptoms after age 50
  • Family history of bowel cancer or inflammatory bowel disease

A confirmed IBS diagnosis is made by a doctor after ruling out other conditions — self-diagnosing should be avoided.