Crohn's Disease
A chronic transmural inflammatory bowel disease that can affect any part of the gut.
Overview
Crohn's disease is a chronic immune-mediated condition causing patchy, full-thickness inflammation anywhere from mouth to anus, most commonly the terminal ileum. It causes diarrhoea, abdominal pain, weight loss and complications such as strictures, fistulae and abscesses.
Symptoms
- • Chronic diarrhoea (sometimes bloody)
- • Abdominal pain (often right lower quadrant)
- • Weight loss, fatigue, fever
- • Mouth ulcers, perianal pain or fistula
- • Growth failure in children
- • Extra-intestinal: arthritis, uveitis, skin lesions
Risk factors
- • Family history of IBD
- • Smoking
- • Age 15–30 (peak)
- • Western diet, urban living
- • Previous gastroenteritis
Causes
- • Dysregulated immune response to gut bacteria in genetically susceptible individuals
- • Smoking doubles the risk and worsens disease
- • Genetic: NOD2, ATG16L1 variants
🚨 Red flags — seek urgent care
- • Severe abdominal pain with vomiting — possible obstruction
- • Fever with abdominal mass — possible abscess
- • Massive rectal bleeding
- • Severe perianal pain
When to seek care
- • Persistent diarrhoea, weight loss or abdominal pain
- • Flare symptoms
- • Any red flag
Diagnosis
- • Faecal calprotectin, CRP
- • Ileocolonoscopy with biopsies — patchy, transmural inflammation, granulomas
- • MRI small bowel for strictures and fistulae
- • Exclude infection (TB, yersinia, parasites)
Treatment
- • Induction: corticosteroids (oral or budesonide), exclusive enteral nutrition (especially in children)
- • Maintenance: thiopurines, methotrexate, or biologics (anti-TNF, vedolizumab, ustekinumab) and JAK inhibitors
- • Smoking cessation is essential
- • Surgery for strictures, fistulae, abscesses or medically refractory disease
- • Nutritional support, bone protection, vaccinations
Prevention
- • Do not smoke
- • Early effective treatment may prevent complications
- • Maintain therapy in remission
Complications
- • Strictures and obstruction
- • Fistulae and abscesses
- • Malabsorption and nutritional deficiencies
- • Increased risk of bowel cancer
- • Osteoporosis
Prognosis
Crohn's is lifelong with a relapsing course. Most people achieve remission with modern therapy; up to half need surgery at some point. Smoking cessation is the strongest modifier of disease course.
Education & self-care
Crohn's disease is treatable. Stopping smoking, adhering to maintenance therapy and early treatment of flares preserve gut function.
Frequently asked questions
Does diet cause Crohn's?
No specific diet causes Crohn's. Exclusive enteral nutrition can induce remission in children. A balanced diet and avoidance of restrictive fads is recommended.
Can Crohn's be cured?
There is no cure, but most people achieve durable remission with the right combination of medication, lifestyle and (sometimes) surgery.
Is Crohn's the same as ulcerative colitis?
Both are inflammatory bowel diseases, but Crohn's can affect any part of the gut from mouth to anus and involves the full bowel wall, while ulcerative colitis is limited to the colon's lining.
Will I need surgery?
About half of people with Crohn's have surgery within 10 years of diagnosis, usually for strictures, fistulas or abscesses. Biologic therapy has reduced both surgery rates and complications.
Does diet cause Crohn's?
Diet does not cause Crohn's, but it can influence symptoms. Exclusive enteral nutrition is first-line for inducing remission in children, and individualised dietary changes help many adults manage flares.