Inflammatory bowel disease (IBD) vs irritable bowel syndrome (IBS)
How to tell them apart, and why the distinction matters
Why this distinction is critical
IBD causes intestinal inflammation and can lead to complications if untreated. IBS is functional without structural inflammation. Confusing them delays diagnosis and treatment.
What is IBD?
Includes Crohn’s disease and ulcerative colitis.
Features that suggest IBD:
- blood or mucus
- nocturnal diarrhoea
- weight loss
- fatigue or anaemia
- raised markers
- family history
What is IBS?
A disorder of gut–brain interaction. IBS is a diagnosis of exclusion.
Features that suggest IBS:
- stress or meal-linked symptoms
- relief after bowel movement
- bloating
- normal tests
- no red flags
Key differences at a glance
| Feature | IBD | IBS |
|---|---|---|
| Inflammation | Yes | No |
| Blood | Common | Absent |
| Night-time symptoms | Yes | Rare |
| Weight loss | Common | No |
| Lab abnormalities | Often | Normal |
| Colonoscopy findings | Abnormal | Normal |
The role of faecal calprotectin
Elevated calprotectin suggests inflammation; normal makes active IBD unlikely. Interpret in context.
Post-infectious IBS
IBS-like symptoms can persist after infection; this is common and does not imply ongoing infection.
Key takeaway: IBD causes inflammation; IBS does not. IBS is diagnosed only after inflammatory disease is excluded.