What Is Ulcerative Colitis?

Ulcerative colitis is a topic that attracts attention from a wide range of readers. This may be because of the chronic nature of the disease and/or its huge social and emotional impact on patients and their families. In this article, various aspects of this condition will be discussed to provide key information regarding the disease. 

Ulcerative colitis is a chronic inflammatory disease characterised by inflammation of the large intestine (the colon and the rectum). It’s a bit similar to Crohn’s disease; however, in Crohn’s disease, the inflammation can affect any part of the gastrointestinal (GI) tract, not just the large intestine. Both conditions can be grouped together as inflammatory bowel diseases. 

In this article, various aspects of ulcerative colitis are discussed, including its key characteristics, treatment, and management. At the end of the article, there are answers to some of the most frequently asked questions about ulcerative colitis to give you a better idea of this topic.


Ulcerative colitis is a form of inflammatory bowel disease which is more common than Crohn’s disease. It affects all genders equally, and the peak age of onset is 20-30 years. When there’s more inflammation and a larger portion of the bowel involved, symptoms tend to worsen.2 Based on the area and the extent of bowel involvement, ulcerative colitis is divided into three types. They are:

  • Proctitis (affecting the rectum)
  • Left-sided colitis (affecting the left colon)
  • Pancolitis (affecting the entire colon) 

The disease is also characterised by repeating phases of remittance (being without symptoms for a period of time) and relapse. This may also involve other parts of the body outside the gastrointestinal tract.3 

Generally, inflammatory bowel diseases are closely related to Western lifestyles and environments, so the disease is more common in regions such as Northern Europe and Northern America. The number of cases reported annually ranges between 9 to 20 cases per 100000.1 

Ulcerative colitis is a life-long condition. One potential complication, and the most common cause of death due to ulcerative colitis, is toxic megacolon, a life-threatening complication characterised by non-obstructive dilatation of a segment or the whole of the colon with associated whole-body toxicity.1,4

Ulcerative colitis increases the risk of developing colorectal cancer by two times more, with those assigned male at birth and those diagnosed with the advanced stage of cancer at a young age having a particularly higher risk.5. 

Causes of ulcerative colitis

Though the exact cause of ulcerative colitis is unknown, there are some key contributors that can contribute to developing ulcerative colitis like:3

  • Genetics: Ulcerative colitis sometimes runs in families. Some research suggests that certain genes can increase the chance of developing ulcerative colitis.
  • Immune system responses: Abnormal immune response can cause inflammation in the large intestine
  • Environmental factors (such as dietary choice and air pollution) 
  • Psychological stress 
  • Smoking
  • Low antioxidant intake, including vitamins E and C, is often found in fruits and leafy greens. 
  • Use of non-steroidal anti-inflammatory drugs (NSAIDs

Signs and symptoms of ulcerative colitis

The disease develops slowly, with the most common initial symptom being the passing of bloody stools. Stools are usually frequent and also associated with the passage of mucus.3 Tenesmus, a frequent but often unsuccessful urge to empty your bowels, is also common. Often, you may only be able to pass blood or mucus because the urge was triggered by the inflammation of the rectum rather than a genuine need to pass stool.

In severe ulcerative colitis, you may also have severe diarrhoea, fever, abdominal cramps, and bloating.6 In addition, there may be symptoms occurring outside the gastrointestinal tract. These may include:

Examination and investigation of patients with ulcerative colitis may reveal:

  • Fever
  • Weight loss
  • Abdominal tenderness
  • Tachycardia (fast heart rate)
  • A digital rectal examination may reveal bloody stool and mucus 

Management and treatment for ulcerative colitis

Before treatment starts, a diagnosis of ulcerative colitis is made through a combination of clinical features, endoscopic findings, biopsy, and by ruling out other possible diagnoses.1

Treatment of ulcerative colitis has three main goals:1

  • Enhancing the quality of life
  • Reduce the chance of developing cancer
  • Achieve remission

When choosing a treatment option, certain factors are used to determine the best choice, including:1

  • The severity of the disease
  • The extent of the disease
  • How we expect the disease to progress

For example, in an isolated rectal form of ulcerative colitis (proctitis), delivering medication specifically to the rectum in the form of a suppository or enema can be sufficient.7

The severity of ulcerative colitis can be graded as mild, moderate, or severe, and the disease stage can be classified as active or remitting.3 In the active stage, symptoms, as well as active mucosal lesions (abnormal patches of the bowel), are present. Meanwhile, when in remission, symptoms subside, and mucosal findings disappear. 

The first-line medications prescribed for ulcerative colitis may include oral or rectal sulfasalazine or 5-aminosalicylates. Steroids can also be added for those who fail to achieve remission. Probiotics have also been used, as well as transplantation of faecal microbiota.3 

Failure to respond to steroids may mean that other medications need to be started, including thiopurines such as azathioprine and 6-mercaptopurines or drugs such as infliximab, adalimumab, golimumab, and vedolizumab, all classified as anti-tumour necrosis factor (TNF)-alpha drugs.3 

Those who achieve remission are placed on maintenance therapy medication to prevent relapse. Commonly used options include aminosalicylates, azathioprine, or 6-mercaptopurines. 

When medical treatment fails, or the patient develops toxic megacolon, perforation, uncontrollable bleeding, cancer, or severe intolerable side effects, surgical treatment in the form of a colectomy is considered.3


How is ulcerative colitis diagnosed?

Diagnosis is made by endoscopy and mucosal biopsy.1 A range of imaging tests including ultrasound, MRI and (less commonly) a CT scan, can be selected based on cost, location of disease, stage, severity, convenience, suitability, or availability. Colonoscopy or proctosigmoidoscopy can show ulceration and other typical features while also giving an opportunity to take samples for tissue analysis. A biopsy sample may reveal a significantly raised platelet-activating factor (a key marker of inflammation)

Blood tests may show elevated erythrocyte sedimentation rate (ESR), C-reactive protein, and elevated white blood cell count (leucocytosis), especially in the active phase of the disease.7 Blood tests can also help exclude other diagnoses and assess the nutritional status of patients. 

How can I prevent ulcerative colitis?

Due to its genetic association, it’s tricky to completely prevent ulcerative colitis. However, it is important to avoid environmental factors such as smoking, minimise psychological stress, avoid unnecessary use of NSAIDs, and eat foods high in antioxidants. 

Who is at risk of ulcerative colitis?

Those who have genetic susceptibility, including those with an abnormal immune response, are at higher risk of developing ulcerative colitis. 

How common is ulcerative colitis?

Ulcerative colitis is more common in the Western and Northern hemispheres; incidence is low in Asia. The number of cases reported annually is estimated to be between 9 to 20 cases per 100000.1 

When should I see a doctor?

If you observe symptoms such as the passage of bloody stools, rectal passage of mucus, or abdominal pains, you should seek medical attention for further investigation. 


Ulcerative colitis is a chronic, debilitating disease that is characterised by periods of relapse and remission. Symptoms are due to inflammation of the large intestine, leading to the passage of bloody stools, mucus, abdominal pains, etc. It is usually diagnosed by endoscopy and biopsy, while laboratory investigations can help by ruling other other potential diagnoses and assessing your overall health. Treatment often involves a combination of drugs aimed at achieving remission. However, in severe cases, surgical removal of part of the bowel may be required. Please visit your GP if you experience any of the symptoms of ulcerative colitis. 


  1. Gajendran M, Loganathan P, Jimenez G, Catinella AP, Ng N, Umapathy C, et al. A comprehensive review and update on ulcerative colitis. Dis Mon. 2019 Dec;65(12):100851.Available from: https://pubmed.ncbi.nlm.nih.gov/30837080/ 
  2. Yeshi K, Ruscher R, Hunter L, Daly NL, Loukas A, Wangchuk P. Revisiting inflammatory bowel disease: pathology, treatments, challenges and emerging therapeutics including drug leads from natural products. Journal of Clinical Medicine [Internet]. 2020 May [cited 2023 Mar 3];9(5):1273. Available from: https://www.mdpi.com/2077-0383/9/5/1273 
  3. Matsuoka K, Kobayashi T, Ueno F, Matsui T, Hirai F, Inoue N, et al. Evidence-based clinical practice guidelines for inflammatory bowel disease. J Gastroenterol [Internet]. 2018 [cited 2023 Mar 3];53(3):305–53. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5847182/ 
  4. Skomorochow E, Pico J. Toxic megacolon. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 [cited 2023 Mar 3]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK547679/ 
  5. Jess T, Rungoe C, Peyrin–Biroulet L. Risk of colorectal cancer in patients with ulcerative colitis: a meta-analysis of population-based cohort studies. Clinical Gastroenterology and Hepatology [Internet]. 2012 Jun 1 [cited 2023 Mar 3];10(6):639–45. Available from: https://www.sciencedirect.com/science/article/pii/S1542356512001097 
  6. Aloi M, D’Arcangelo G, Pofi F, Vassallo F, Rizzo V, Nuti F, et al. Presenting features and disease course of pediatric ulcerative colitis. J Crohns Colitis. 2013 Dec;7(11):e509-515. Available from: https://pubmed.ncbi.nlm.nih.gov/23583691/ 
  7. Lynch WD, Hsu R. Ulcerative colitis. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 [cited 2023 Mar 4]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK459282/ 
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Abdul-Azeez Kuna

Master of Public Health - MPH, University of Liverpool

Hi! I am Abdul. I recently completed my MPH degree from the University of Liverpool.
I joined the public health degree from a medical background and am currently looking forward to proceeding with a PhD. As a way of contributing to public health, I am leveraging the internet space to provide health education and awareness for people to gain knowledge and do what they can to improve their health. With many people searching for health information online, there is a huge advantage to reaching a wider audience. Providing easy-to-read articles backed by evidence is key to ensuring they are not misinformed. As you read this article, I hope it improves your understanding of this health topic and more importantly, motivates you to take preventive measures

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