Rome IV Diagnostic Criteria
IBS Diagnosis
Recurrent abdominal pain, on average ≥1 day/week in the last 3 months, associated with ≥2 of: (1) related to defecation, (2) associated with change in stool frequency, (3) associated with change in stool consistency. Onset ≥6 months before diagnosis.
IBS Subtypes
| Subtype | Stool Type | Symptoms | Approach |
|---|---|---|---|
| IBS-C (constipation-predominant) | Hard, lumpy (BSS 1–2) | Bloating, abdominal pain, infrequent stools | Fibre (soluble), linaclotide, low-FODMAP |
| IBS-D (diarrhoea-predominant) | Loose, watery (BSS 6–7) | Urgency, frequent stools, post-meal pain | Low-FODMAP, loperamide, antispasmodics |
| IBS-M (mixed) | Both hard and loose | Alternating pattern | Low-FODMAP; treat predominant subtype |
| IBS-U (unclassified) | Doesn't fit above | Variable | General IBS management |
Evidence-Based Management
- Low-FODMAP diet (Monash University app) — work with a dietitian; 75% success rate
- Antispasmodics (mebeverine, hyoscine butylbromide) — for pain and cramps
- Peppermint oil (enteric-coated) — antispasmodic effect
- Gut-directed hypnotherapy or CBT — strong evidence for gut-brain modulation
- Regular meals; reduce alcohol and caffeine; increase soluble fibre (oats, linseeds)
Low-FODMAP Is Not ForeverThe elimination phase is for 6–8 weeks only. Then systematically reintroduce FODMAP groups to identify personal triggers. Most people can liberalise their diet significantly after identifying their specific sensitivities.
What are FODMAPs?
Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols — short-chain carbohydrates poorly absorbed in the small intestine. They ferment in the large bowel, causing gas, bloating, and altered motility in IBS.
Do I need a colonoscopy for IBS?
IBS is a clinical diagnosis (Rome IV criteria). Colonoscopy is not routine but is recommended if alarm features are present: rectal bleeding, unintentional weight loss, iron deficiency, onset >50, family history of bowel cancer, or nocturnal symptoms.
Can stress cause IBS?
Yes. The gut-brain axis is central to IBS pathophysiology. Psychological stress directly alters gut motility, visceral sensitivity, and the gut microbiome. CBT, gut-directed hypnotherapy, and mindfulness significantly reduce IBS severity.
Is IBS different from IBD?
Yes. IBS (irritable bowel syndrome) is a functional disorder — no structural damage. IBD (inflammatory bowel disease — Crohn's or ulcerative colitis) involves inflammation and tissue damage. IBS does not cause cancer; IBD does increase cancer risk.
Medical Disclaimer: This page is for general education only and does not replace professional medical advice. Always consult a qualified healthcare provider.