Ulcerative Colitis

Ulcerative Colitis — scientific infographic poster
UC severity endoscopy

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Table of Contents

  1. What is Ulcerative Colitis?
  2. Common Symptoms of Ulcerative Colitis
  3. Extent and Severity
  4. Causes and Risk Factors
  5. Diagnosis
  6. Treatment Options
  7. Diet and Nutrition: What the Research Reports
  8. Probiotics, Faecal Transplants and Curcumin: What the Trials Show
  9. Long-Term Care: What the Guidelines Describe
  10. Complications of Ulcerative Colitis
  11. Key Research Papers
  12. Connections
  13. Featured Videos

What is Ulcerative Colitis?

Ulcerative colitis is a chronic inflammatory bowel disease (IBD) of the large intestine. It inflames the inner lining (mucosa) of the colon, usually starting in the rectum and extending upward in a continuous stretch through part or all of the colon (Ordás 2012; Ungaro 2017). The 2025 American College of Gastroenterology (ACG) guideline describes it as a disease of unknown cause whose course is most often relapsing and remitting — flares alternating with periods of remission — while some people have persistent activity despite treatment and a small number present with a rapidly progressing, severe (fulminant) colitis (Rubin 2025). A 2017 Lancet review reports that up to 15% of patients first present with severe disease (Ungaro 2017).

How common it is. Using US commercial and public insurance data, the ACG guideline cites an incidence of 6.3 per 100,000 person-years and a prevalence of 305 per 100,000, extrapolated to about 1.25 million people living with ulcerative colitis in the United States in 2020 (Rubin 2025). A systematic review of population-based studies found the highest reported prevalence in Europe (505 per 100,000 in Norway) and North America (286 per 100,000 in the USA); 15 of 18 studies of ulcerative colitis in North America and Europe reported stable or decreasing incidence, while incidence has been rising since 1990 in newly industrialised countries in Africa, Asia and South America (Ng 2017).

Common Symptoms of Ulcerative Colitis

The ACG guideline states that ulcerative colitis should be suspected in people with blood in the stool, more frequent stools, or bowel urgency (Rubin 2025). Symptoms described in the guideline and in the Lancet review include:

The guideline also lists symptoms outside the bowel that a full history covers: joint pain or swelling, skin lesions, eye inflammation, mouth sores, and jaundice or itching that can point to liver or bile-duct involvement (Rubin 2025).

Extent and Severity

The ACG guideline groups ulcerative colitis by how much of the bowel is inflamed (Rubin 2025):

The guideline’s figure of clinical patterns also shows proctosigmoiditis (rectum and sigmoid colon) as a traditional phenotype, along with a cecal-patch pattern and the relative rectal sparing seen with primary sclerosing cholangitis.

In population-based studies, 30–60% of patients have proctitis at presentation, 16–45% left-sided colitis and 14–35% extensive colitis; the disease extends further up the colon in 10–19% of patients after 5 years and in up to 28% at 10 years (Ungaro 2017). The guideline notes that the rectum is not involved in fewer than 5% of adults at diagnosis, but in up to a third of children with colitis onset (Rubin 2025).

Severity is graded separately, as mild, moderate or severe, using symptoms, endoscopy (for example the Mayo endoscopic score, from 0 for normal or inactive mucosa to 3 for severely active disease), blood and stool markers, and the course of the disease. Acute severe ulcerative colitis is defined in the guideline as six or more bowel movements a day with at least one sign of systemic toxicity — a fast heart rate, fever, anaemia (haemoglobin below 10.5 g/dL) or a raised ESR (above 30 mm/hr). Historical cohorts cited by the guideline found that up to a quarter of people with ulcerative colitis may develop it and need hospital care, with colectomy in up to 40% of those patients (Rubin 2025).

Causes and Risk Factors

The ACG guideline states that the causes of ulcerative colitis remain complex and unknown (Rubin 2025). The Lancet review describes the disease as multifactorial, involving genetic predisposition, defects in the gut’s epithelial barrier, dysregulated immune responses and environmental factors (Ungaro 2017).

Diagnosis

The ACG guideline describes diagnosis as resting on lower-bowel endoscopy with tissue confirmation (Rubin 2025):

Treatment Options

The 2025 ACG guideline organises treatment by disease activity and prognosis, and separates treatment that induces remission from treatment that maintains it. It recommends treating to achieve endoscopic improvement (a Mayo endoscopic score of 0 or 1) to increase the likelihood of sustained steroid-free remission and to prevent hospitalisation and surgery (strong recommendation, moderate-quality evidence), and recommends faecal calprotectin to assess response, suspected relapse and maintenance (Rubin 2025). The figures below are those the guideline and the cited trials report.

Mildly to moderately active disease

Moderately to severely active disease

For induction of remission the guideline recommends each of the following drug classes, and recommends continuing the same drug for maintenance in people who respond to it (Rubin 2025):

The guideline notes that people respond better to their first advanced therapy than after one or more others have failed, and that no validated biomarker yet predicts which drug will work for a given person.

Acute severe ulcerative colitis

The guideline describes hospital care with intravenous corticosteroids, fluids and electrolytes; testing for C. difficile; a flexible sigmoidoscopy within 72 hours, with biopsies for cytomegalovirus; and assessment for toxic megacolon. It recommends rescue therapy with infliximab or cyclosporine, and surgical consultation, when there is not an adequate response to intravenous steroids by day 3. It states that NSAIDs, narcotics and drugs with anticholinergic effects should be avoided in acute severe colitis, and that hospitalised patients with acute colitis receive low-molecular-weight heparin to prevent blood clots (Rubin 2025).

Surgery

Diet and Nutrition: What the Research Reports

People with IBD often link symptoms to food. In a questionnaire of 400 consecutive IBD clinic patients (51% with ulcerative colitis), 57% felt diet could trigger a flare, 60% reported worse symptoms with certain foods, about two-thirds went without favourite foods to prevent relapse, and nearly half had never received formal dietary advice; the authors noted that whether the symptoms reflected active inflammation could not be determined (Limdi 2016). What studies of diet and disease activity report:

Probiotics, Faecal Transplants and Curcumin: What the Trials Show

Long-Term Care: What the Guidelines Describe

Complications of Ulcerative Colitis

Key Research Papers

Historical Background

Samuel Wilks is credited with first describing ulcerative colitis, in 1859 (Gajendran 2019); a historical review lists his account among the careful early descriptions of then-obscure intestinal inflammation and notes that the early history of the disease is entangled with infectious colitis (Kirsner 1988). Sulfasalazine, the first drug of the aminosalicylate family, was developed by Nanna Svartz, whose 1942 report in Acta Medica Scandinavica included therapeutic results in ulcerative colitis (Svartz 1942); she later described its discovery and development (Svartz 1988). The History of Ulcerative Colitis page covers this in more detail.

  1. Ordas I, Eckmann L, Talamini M, Baumgart DC, Sandborn WJ. Ulcerative colitis. The Lancet. 2012;380(9853):1606-1619. — doi:10.1016/S0140-6736(12)60150-0
  2. Danese S, Fiocchi C. Ulcerative colitis. N Engl J Med. 2011;365(18):1713-1725. — doi:10.1056/NEJMra1102942
  3. Rubin DT, Ananthakrishnan AN, Siegel CA, et al. ACG clinical guideline: ulcerative colitis in adults. Am J Gastroenterol. 2019;114(3):384-413. — doi:10.14309/ajg.0000000000000152 (updated by the 2025 guideline below)
  4. Feagan BG, Rutgeerts P, Sands BE, et al. Vedolizumab as induction and maintenance therapy for ulcerative colitis (GEMINI 1). N Engl J Med. 2013;369(8):699-710. — doi:10.1056/NEJMoa1215734
  5. Sandborn WJ, Su C, Sands BE, et al. Tofacitinib as induction and maintenance therapy for ulcerative colitis (OCTAVE). N Engl J Med. 2017;376(18):1723-1736. — doi:10.1056/NEJMoa1606910
  6. Rutgeerts P, Sandborn WJ, Feagan BG, et al. Infliximab for induction and maintenance therapy for ulcerative colitis (ACT trials). N Engl J Med. 2005;353(23):2462-2476. — doi:10.1056/nejmoa050516
  7. Ng SC, Shi HY, Hamidi N, et al. Worldwide incidence and prevalence of inflammatory bowel disease in the 21st century. The Lancet. 2017;390(10114):2769-2778. — doi:10.1016/S0140-6736(17)32448-0
  8. Harbord M, Eliakim R, Bettenworth D, et al. Third European evidence-based consensus on diagnosis and management of ulcerative colitis. Part 2: current management (ECCO). J Crohns Colitis. 2017;11(7):769-784. — doi:10.1093/ecco-jcc/jjx009 — carries a 2022 correction notice, amended in 2024, concerning cited studies of a multi-strain probiotic whose commercial formulation changed after 2016; an earlier expression of concern was withdrawn (correction notice: PubMed PMID: 35971821)
  9. Jostins L, Ripke S, Weersma RK, et al. Host-microbe interactions have shaped the genetic architecture of inflammatory bowel disease. Nature. 2012;491(7422):119-124. — doi:10.1038/nature11582
  10. Kornbluth A, Sachar DB. Ulcerative colitis practice guidelines in adults: American College of Gastroenterology Practice Parameters Committee. Am J Gastroenterol. 2010;105(3):501-523. — doi:10.1038/ajg.2009.727 (superseded by the 2019 and 2025 ACG guidelines)
  11. Ungaro R, Mehandru S, Allen PB, Peyrin-Biroulet L, Colombel JF. Ulcerative colitis. The Lancet. 2017;389(10080):1756-1770. — doi:10.1016/s0140-6736(16)32126-2
  12. Kaplan GG. The global burden of IBD: from 2015 to 2025. Nat Rev Gastroenterol Hepatol. 2015;12(12):720-727. — doi:10.1038/nrgastro.2015.150
  13. Rubin DT, Ananthakrishnan AN, Siegel CA, Barnes EL, Long MD. ACG clinical guideline update: ulcerative colitis in adults. Am J Gastroenterol. 2025;120(6):1187-1224. — PubMed PMID: 40701556 (correction published 2026: PubMed PMID: 41384833)
  14. Hashash JG, Elkins J, Lewis JD, Binion DG. AGA clinical practice update on diet and nutritional therapies in patients with inflammatory bowel disease: expert review. Gastroenterology. 2024;166(3):521-532. — PubMed PMID: 38276922
  15. Levine A, Rhodes JM, Lindsay JO, et al. Dietary guidance from the International Organization for the Study of Inflammatory Bowel Diseases. Clin Gastroenterol Hepatol. 2020;18(6):1381-1392. — PubMed PMID: 32068150
  16. Jowett SL, Seal CJ, Pearce MS, Phillips E, Gregory W, Barton JR, Welfare MR. Influence of dietary factors on the clinical course of ulcerative colitis: a prospective cohort study. Gut. 2004;53(10):1479-1484. — PubMed PMID: 15361498
  17. Wedlake L, Slack N, Andreyev HJ, Whelan K. Fiber in the treatment and maintenance of inflammatory bowel disease: a systematic review of randomized controlled trials. Inflamm Bowel Dis. 2014;20(3):576-586. — PubMed PMID: 24445775
  18. Limdi JK, Aggarwal D, McLaughlin JT. Dietary practices and beliefs in patients with inflammatory bowel disease. Inflamm Bowel Dis. 2016;22(1):164-170. — PubMed PMID: 26383912
  19. Narula N, Wong ECL, Dehghan M, et al. Association of ultra-processed food intake with risk of inflammatory bowel disease: prospective cohort study. BMJ. 2021;374:n1554. — PubMed PMID: 34261638
  20. Kaur L, Gordon M, Baines PA, et al. Probiotics for induction of remission in ulcerative colitis. Cochrane Database Syst Rev. 2020;3(3):CD005573. — PubMed PMID: 32128795
  21. Iheozor-Ejiofor Z, Kaur L, Gordon M, et al. Probiotics for maintenance of remission in ulcerative colitis. Cochrane Database Syst Rev. 2020;3(3):CD007443. — PubMed PMID: 32128794
  22. Imdad A, Pandit NG, Zaman M, et al. Fecal transplantation for treatment of inflammatory bowel disease. Cochrane Database Syst Rev. 2023;4(4):CD012774. — PubMed PMID: 37094824
  23. Lang A, Salomon N, Wu JC, et al. Curcumin in combination with mesalamine induces remission in patients with mild-to-moderate ulcerative colitis in a randomized controlled trial. Clin Gastroenterol Hepatol. 2015;13(8):1444-1449.e1. — PubMed PMID: 25724700
  24. Kedia S, Bhatia V, Thareja S, et al. Low dose oral curcumin is not effective in induction of remission in mild to moderate ulcerative colitis: results from a randomized double blind placebo controlled trial. World J Gastrointest Pharmacol Ther. 2017;8(2):147-154. — PubMed PMID: 28533925
  25. Ben-Horin S, Salomon N, Karampekos G, et al. Curcumin-QingDai combination for patients with active ulcerative colitis: a randomized, double-blinded, placebo-controlled trial. Clin Gastroenterol Hepatol. 2024;22(2):347-356.e6. — PubMed PMID: 37302449
  26. Gajendran M, Loganathan P, Jimenez G, et al. A comprehensive review and update on ulcerative colitis. Dis Mon. 2019;65(12):100851. — PubMed PMID: 30837080
  27. Kirsner JB. Historical aspects of inflammatory bowel disease. J Clin Gastroenterol. 1988;10(3):286-297. — PubMed PMID: 2980764
  28. Svartz N. Salazopyrin, a new sulfanilamide preparation. A. Therapeutic results in rheumatic polyarthritis. B. Therapeutic results in ulcerative colitis. C. Toxic manifestations in treatment with sulfanilamide preparations. Acta Med Scand. 1942;110(6):577-598. — doi:10.1111/j.0954-6820.1942.tb06841.x
  29. Svartz N. Sulfasalazine: II. Some notes on the discovery and development of salazopyrin. Am J Gastroenterol. 1988;83(5):497-503. — PubMed PMID: 2896459

PubMed Topic Searches

Curated PubMed topic searches of peer-reviewed literature on Ulcerative Colitis. Each link opens a live PubMed query so you always see the most current studies.

  1. PubMed: UC treatment guidelines
  2. PubMed: Mesalamine in UC
  3. PubMed: Biologic therapy in UC
  4. PubMed: Vedolizumab in UC
  5. PubMed: Tofacitinib in UC
  6. PubMed: Colectomy and IPAA
  7. PubMed: CRC surveillance
  8. PubMed: FMT in UC
  9. PubMed: Acute severe UC
  10. PubMed: Pediatric UC
  11. PubMed: UC and PSC
  12. PubMed: Quality of life in UC

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Connections

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