VHOSPITAL.CLINIC · Differential Diagnosis

Crohn's Disease vs Irritable Bowel Syndrome (IBS)

Clinical comparison — shared symptoms, key differences, distinguishing diagnostic tests, treatment pathways, and when to seek urgent evaluation.

Condition Overview

Condition A

Crohn's Disease

Crohn's disease is a chronic inflammatory bowel disease that can affect any part of the GI tract from mouth to anus, causing abdominal pain, diarrhea, and malnutrition. Skip lesions and transmural inflammation are pathological hallmarks.

Condition B

Irritable Bowel Syndrome (IBS)

IBS is a functional gastrointestinal disorder causing recurrent abdominal pain related to defecation, with altered stool frequency or consistency. It affects up to 15% of the population; dietary changes, stress management, and symptom-specific medications help.

Shared Symptoms — Why They're Confused

Both conditions present with 2 overlapping symptoms, making clinical differentiation essential.

abdominal pain diarrhea

Key Clinical Differences

Crohn's Disease

Abdominal pain and diarrhoea
Bloating
Fatigue
Symptoms triggered by stress or certain foods

Irritable Bowel Syndrome (IBS)

Transmural inflammation affecting any part of GI tract
Perianal disease (fistulae, abscesses)
Elevated CRP and faecal calprotectin
Extra-intestinal manifestations: uveitis, arthritis, erythema nodosum

Distinguishing Diagnostic Tests

Test	Crohn's Disease	Irritable Bowel Syndrome (IBS)
Faecal calprotectin	Elevated (>200 μg/g) — intestinal inflammation	Normal (<50 μg/g) — functional disorder, no mucosal inflammation
Colonoscopy + biopsy	Skip lesions, cobblestone mucosa, granulomas on histology	Normal mucosa and histology
CRP + ESR	Elevated in active Crohn's disease	Normal — IBS has no systemic inflammation

Treatment Approaches

Crohn's Disease

•Aminosalicylates, corticosteroids (acute flares)
•Immunomodulators (azathioprine, methotrexate)
•Biologics (anti-TNF, vedolizumab)
•Surgery for complications (strictures, fistulae)

Irritable Bowel Syndrome (IBS)

•Low-FODMAP diet
•Antispasmodics (mebeverine)
•Antidiarrhoeal agents (loperamide)
•Psychological therapy (CBT) for gut-brain axis

When Doctors Consider Each Diagnosis

🔵 Consider Crohn's Disease when:

→Rectal bleeding, perianal disease, elevated calprotectin, abnormal colonoscopy

🟢 Consider Irritable Bowel Syndrome (IBS) when:

→Normal colonoscopy and calprotectin, symptoms related to stress and diet, no weight loss or blood in stool

Explore Each Condition in Detail

Crohn's DiseaseOverview →Irritable Bowel Syndrome (IBS)Overview →

Related Clinical Pages

Crohn's Disease

→Crohn's Disease — Overview →Crohn's Disease — Treatment →Crohn's Disease — Differential Diagnosis →Crohn's Disease — Prognosis →Crohn's Disease — Complications

Irritable Bowel Syndrome (IBS)

→Irritable Bowel Syndrome (IBS) — Overview →Irritable Bowel Syndrome (IBS) — Treatment →Irritable Bowel Syndrome (IBS) — Differential Diagnosis →Irritable Bowel Syndrome (IBS) — Prognosis →Irritable Bowel Syndrome (IBS) — Complications →Irritable Bowel Syndrome (IBS) — Evidence

Medical References

Content on this page is informed by evidence-based clinical sources including:

World Health Organization (WHO)Global health guidance and disease classification
National Health Service (NHS)UK clinical guidelines and patient information
National Institute for Health and Care Excellence (NICE)Evidence-based clinical practice guidelines
Centers for Disease Control and Prevention (CDC)US public health data and clinical recommendations
PubMed – NCBIPeer-reviewed biomedical literature and clinical studies
Cochrane LibrarySystematic reviews and meta-analyses in evidence-based medicine

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