CONDITIONS
Ulcerative Colitis & Crohn’s Disease
Inflammatory Bowel Disease (IBD): symptoms, differences, tests and treatment
Ulcerative colitis and Crohn’s disease are the two main types of inflammatory bowel disease (IBD). They can cause similar symptoms (such as diarrhoea, abdominal pain and bleeding), but they affect the bowel in different ways. With modern treatments, many people achieve good control of symptoms and long periods of remission.
What is inflammatory bowel disease (IBD)?
IBD describes long-term inflammation in the digestive tract. The two main types are: ulcerative colitis (inflammation mainly in the large bowel/colon) and Crohn’s disease (inflammation that can affect any part of the gut).
Important: IBD is not the same as IBS (irritable bowel syndrome). IBS does not cause inflammation, bleeding or bowel damage, whereas IBD can.
Ulcerative colitis vs Crohn’s: what’s the difference?
- Affects the colon (large bowel)
- Inflammation is usually continuous (no “skips”)
- Mainly affects the inner lining of the bowel wall
- Common symptom: bloody diarrhoea
- Can affect any part of the gut (mouth to anus)
- Often has “skip lesions” (patchy areas)
- Inflammation can be deeper through the bowel wall
- More likely to cause strictures (narrowing) or fistulas
What are the symptoms?
Symptoms vary, and may fluctuate between flare-ups and remission. Common symptoms include:
- Diarrhoea (sometimes urgent, sometimes at night)
- Blood and/or mucus in the stool (more common in ulcerative colitis)
- Abdominal pain and cramping
- Urgency and feeling of incomplete emptying (tenesmus)
- Fatigue, low energy, or weight loss
- Fever during significant inflammation/infection
Symptoms outside the bowel (extra-intestinal)
- Joint pains / arthritis
- Skin rashes or painful red lumps (e.g., erythema nodosum)
- Eye inflammation (red painful eye, blurred vision)
- Mouth ulcers
Seek urgent assessment if you have severe abdominal pain, persistent vomiting, high fever, passing large amounts of blood, signs of dehydration, fainting, or a swollen/tender abdomen.
What causes ulcerative colitis and Crohn’s disease?
The exact cause is not fully known. IBD is thought to involve an overactive immune response in people with a genetic tendency, influenced by environmental factors. It is not caused by stress (though stress can worsen symptoms), and it is not contagious.
How is IBD diagnosed?
Diagnosis usually involves a combination of history, examination, blood/stool tests, and imaging or endoscopy. The key test is often colonoscopy (camera test), sometimes with biopsies.
- Blood tests: inflammation markers, anaemia, nutrition markers
- Stool tests: calprotectin (inflammation marker), infection checks
- Endoscopy: sigmoidoscopy/colonoscopy with biopsies
- Imaging: CT/MRI (especially for Crohn’s small bowel disease or complications)
How is ulcerative colitis and Crohn’s treated?
Treatment is tailored to severity, disease location, and whether you are in flare or remission. Goals are to reduce inflammation, control symptoms, heal the bowel lining, and prevent relapse/complications.
- 5-ASAs (often used in ulcerative colitis)
- Steroids for short-term flare control
- Immunomodulators (immune-calming medicines)
- Biologics / targeted therapies for moderate–severe disease
- Antibiotics in select situations (e.g., complications)
- Nutrition support (especially if weight loss or deficiencies)
- Iron/B12/folate replacement when needed
- Smoking cessation (especially important in Crohn’s)
- Vaccinations and medication monitoring (if on immune therapies)
Diet changes can help symptoms, but specific diets should be guided by your clinician/dietitian—especially during flares.
If you are taking immune-suppressing medicines, you may need regular blood tests and infection risk advice. Always follow your specialist team’s guidance.
What complications can occur?
- Strictures (narrowing) causing blockage symptoms
- Fistulas (abnormal connections) and abscesses
- Perianal disease (pain, discharge, fissures)
- Severe colitis and heavy bleeding
- Toxic megacolon (rare but serious)
- Long-term inflammation can increase bowel cancer risk in some people (surveillance plans may be advised)
When is surgery needed?
Surgery is not needed for most people, but may be recommended if medicines don’t control the disease, if there are complications, or if there is severe disease requiring urgent treatment.
- Crohn’s: surgery may address strictures, fistulas or diseased segments, but Crohn’s can recur elsewhere
- Ulcerative colitis: removing the colon can be curative for colitis, and options may include pouch surgery or stoma (specialist discussion)
Living with IBD: flare-ups and remission
Many people have periods of remission with few or no symptoms. Recognising early flare signs and having a clear plan with your GP/IBD team can reduce the risk of severe flare-ups.
- Know your usual pattern and triggers
- Don’t ignore new bleeding, fever, or significant pain
- Take maintenance medication as advised
- Ask about monitoring, vaccinations and screening plans
Quick Questions
Is IBD the same as IBS?
No. IBS does not cause inflammation or bleeding. IBD involves inflammation and may need medical treatment and monitoring.
Can diet cure ulcerative colitis or Crohn’s?
Diet can help symptoms and nutrition, but IBD usually requires medical management. A dietitian can help tailor safe changes.
When should I seek urgent assessment?
Seek urgent help for severe pain, high fever, dehydration, persistent vomiting, large-volume bleeding, or a swollen/tender abdomen.