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Crohn’s Disease and Ulcerative Colitis: Symptoms, Causes & Treatment

By Dr. Deepak Lahoti in Gastroenterology, Hepatology & Endoscopy

Mar 24 , 2025 | 2 min read

Inflammatory Bowel Disease (IBD) affects millions globally, causing chronic inflammation in the digestive tract. While Crohn’s Disease and Ulcerative Colitis (UC) are the two primary types of IBD, they’re often confused due to overlapping symptoms like abdominal pain, diarrhoea, and fatigue. However, understanding their differences is critical for accurate diagnosis and effective treatment.

What is Crohn’s Disease?

Crohn’s Disease is a long-term inflammatory disorder that can impact any section of the gastrointestinal (GI) tract, ranging from the mouth to the anus. However, it most commonly targets the small intestine and colon.

Key Features of Crohn’s Disease

Patchy Inflammation: Damaged areas appear in “skip lesions” (healthy tissue between inflamed regions).
Transmural Involvement: Inflammation penetrates deep into all layers of the intestinal wall.
Complications: Fistulas (abnormal tunnels between organs), strictures (narrowed intestines), malnutrition, and abscesses.

Common Symptoms

Persistent diarrhea
Abdominal cramps and pain (often in the lower right side)
Unintended weight loss
Fatigue
Mouth sores

What is Ulcerative Colitis?

Ulcerative Colitis (UC) is characterised by continuous inflammation limited to the colon (large intestine) and rectum. Unlike Crohn’s, UC only affects the innermost lining of the colon.

Key Features of Ulcerative Colitis

Continuous Inflammation: Damaged areas are contiguous, starting at the rectum and extending upward.
Superficial Ulcers: Sores form on the colon’s mucosal lining, causing bleeding and pus.
Complications: Toxic megacolon (life-threatening colon swelling), severe bleeding, and increased colon cancer risk.

Common Symptoms

Bloody diarrhoea or stools with mucus
Urgent bowel movements
Rectal pain
Tenesmus (feeling of incomplete emptying)
Anaemia due to blood loss

Causes and Risk Factors

While the exact cause of IBD is unknown, research suggests a combination of factors:

Genetics: 10-25% of IBD patients have a family history. Mutations in genes like NOD2 are linked to Crohn’s.
Immune System Dysfunction: The body mistakenly attacks healthy gut bacteria, triggering inflammation.
Environmental Triggers: Smoking (increases Crohn’s risk), diet, stress, and NSAID overuse.
Gut Microbiome Imbalance: Reduced diversity in gut bacteria may play a role.

Diagnosing IBD: Tests and Procedures

Accurate diagnosis requires a combination of methods:

Colonoscopy with Biopsy: The gold standard for differentiating Crohn’s and UC.
Imaging: MRI, CT scans, or capsule endoscopy to visualise minor intestine damage (common in Crohn’s).
Blood/Stool Tests: Check for anaemia, inflammation markers (CRP, calprotectin), and infections.
Pro Tip: Crohn’s is often more complicated to diagnose due to its variable location and deeper inflammation.

Treatment Options for Crohn’s and UC

While there’s no cure for IBD, treatments aim to reduce inflammation, manage symptoms, and prevent complications.

Medications

Anti-Inflammatories: Aminosalicylates (e.g., mesalamine) for mild UC.
Immunosuppressants: Azathioprine, methotrexate.
Biologics: TNF-alpha inhibitors (e.g., infliximab) target specific immune pathways.
Corticosteroids: Short-term use for flare-ups.

Surgery

Crohn’s: Strictureplasty or resection of damaged bowel sections.
UC: Colectomy (removal of the colon) can be curative.

Diet and Lifestyle

Crohn’s: Low-residue diets during flares; avoid trigger foods like dairy or high-fiber items.
UC: Omega-3 fatty acids may reduce inflammation; avoid alcohol and spicy foods.

Conclusion

Crohn’s Disease and Ulcerative Colitis are lifelong conditions that require tailored care. While they share similarities, understanding their differences in affected areas, inflammation patterns, and complications is crucial for effective management. Advances in biologics and personalised medicine offer hope for a better quality of life. If you suspect IBD, consult a gastroenterologist promptly—early intervention can prevent irreversible damage.