Ulcerative Colitis
Diagnosis, severity classification, and stepwise management from aminosalicylates to biologics
Ulcerative colitis is a chronic inflammatory bowel disease that affects the inner lining of the colon and rectum. Unlike Crohn's disease, it always starts in the rectum and spreads continuously — never skipping sections. Careful evaluation of disease severity and extent determines which treatment is needed, from topical aminosalicylates to hospital admission for acute severe colitis.
What is Ulcerative Colitis?
Ulcerative colitis (UC) is a chronic, relapsing-remitting condition in which the mucosal lining of the colon and rectum becomes inflamed. The hallmark is continuous inflammation starting from the rectum — proctitis (rectum only), left-sided colitis (up to the splenic flexure), or extensive colitis/pancolitis (beyond the splenic flexure). Unlike Crohn's disease, UC never affects the small bowel and the inflammation does not go through the full thickness of the bowel wall. Most patients follow a relapsing-remitting course with periods of active symptoms (flares) and periods of remission.
Symptoms and How UC Differs from Crohn's
The cardinal symptom of UC is bloody diarrhoea — often with mucus, urgency, and tenesmus (a feeling of needing to pass stool even when the bowel is empty). Abdominal pain and cramping are common, particularly in the left lower abdomen. Fatigue and iron-deficiency anaemia result from chronic blood loss. In severe flares, patients develop fever, rapid heart rate, and significant weight loss. UC can also cause problems outside the gut — including painful skin lesions (erythema nodosum), eye inflammation (uveitis), joint pain, and in some patients, primary sclerosing cholangitis (a serious liver condition associated with UC).
How Severe is It? Truelove and Witts Criteria
NICE NG130 uses the Truelove and Witts criteria to classify severity. Mild UC means fewer than four stools per day with minimal systemic upset. Moderate UC means four to six stools per day with minor systemic features. Severe UC means more than six bloody stools per day combined with systemic features — heart rate above 90 beats per minute, temperature above 37.8°C, haemoglobin below 105 g/L, or CRP above 30 mg/L. Acute severe UC requires immediate hospital admission for intravenous treatment and close monitoring for life-threatening complications. Assessment and careful evaluation of severity at every contact guides the right level of treatment.
Treatment — From Mild to Severe
Treatment follows a stepwise approach based on disease severity and extent. For proctitis and left-sided mild-moderate UC, topical aminosalicylates (mesalazine suppositories or enemas) are the most effective first-line treatment — more so than oral preparations alone. For more extensive disease, oral mesalazine is added. Maintenance with daily aminosalicylates — even during remission — is essential to prevent relapse. For moderate-severe flares uncontrolled by aminosalicylates, oral prednisolone is used to induce remission but must never be used long-term. Patients needing two or more steroid courses per year should be offered azathioprine or mercaptopurine to maintain remission without steroids.
Biologic Therapies and Advanced Treatments
For patients with moderate-severe UC who fail conventional therapy, biologic medicines — infliximab, adalimumab, vedolizumab, or ustekinumab — are available on the NHS following NICE approval. These target specific parts of the immune system to reduce inflammation. Vedolizumab is gut-selective, making it a useful option when there are concerns about systemic immune suppression. JAK inhibitors such as tofacitinib offer an oral alternative. For acute severe UC not responding to intravenous steroids after 72 hours, ciclosporin or infliximab may be used as rescue therapy before surgery is considered. All patients with long-standing UC require regular colonoscopy surveillance because chronic inflammation increases the risk of colorectal cancer.