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Ulcerative colitis

7-minute read

What is ulcerative colitis?

Ulcerative colitis (UC) is an inflammatory bowel disease. It is sometimes referred to simply as 'colitis'.

It causes painful swelling and redness (inflammation) in the digestive tract. This can lead to symptoms such as abdominal pain and diarrhoea. It’s estimated that more than 33,000 Australians have UC.

Inflammation is a normal way in which the immune system defends the body when fighting off invaders, such as bacteria or viruses. Usually, the inflammation disappears once the invaders are destroyed. With UC, a problem with the immune system causes the inflammation to continue, damaging the walls of the digestive tract.

The difference between ulcerative colitis and Crohn's disease

Crohn's disease is also an inflammatory bowel disease (IBD). The 2 diseases affect the digestive tract differently:

  • Ulcerative colitis only affects the large bowel (colon and/or rectum), and inflammation is only in the surface layers of the bowel lining. It causes ulcers (tiny, open sores) to form in the lining of the bowel.
  • Crohn's disease can affect any part of the digestive tract, from the mouth to the anus (back passage), but usually just the last section of the small bowel (the ileum) and/or the colon. Inflammation can extend into the entire thickness of the bowel wall.

What are the symptoms of ulcerative colitis?

Symptoms tend to vary between individuals and come and go over time, as the inflammation flares up then eases again.

The ulcers that form in the bowel can cause bleeding, so blood and mucus are often present in the stool (poo).

Ulcerative colitis can also cause diarrhoea since the inflamed bowel is less able to absorb water. A person with UC may also experience abdominal cramps and need to open their bowels urgently.

Other symptoms may include fatigue, reduced appetite and weight loss.

Who gets ulcerative colitis and what causes it?

Colitis can develop at any age, but usually first appears in people aged 15 to 30.

Experts are not sure why UC or Crohn's disease occurs in some people. It may be due to a combination of genetic, environmental and infectious factors that cause a fault in the immune system — leading to inflammation of the bowel.


Studies have shown that you are slightly more likely to develop UC or Crohn's if you have a close relative (mother, father, sister or brother) with it. Certain ethnic groups (Caucasians, for example) are also more likely to develop these conditions.

Researchers have identified several genes that are more common in people with colitis, but they have not been able to show that any of these genes actually cause the condition.


UC is more common in people living in Australia, Western Europe and America than in developing countries in Asia and Africa. Researchers have suggested that a modern, Western lifestyle may play a role in causing colitis in susceptible people.


Some experts think that a previous bacterial infection can trigger an abnormal immune response in some people, causing UC to develop. This is still under investigation.

How is ulcerative colitis diagnosed?

Colitis shares many symptoms with other common conditions, such as Crohn's disease, irritable bowel syndrome, gastroenteritis and coeliac disease. Your doctor will examine you and take a detailed history of your symptoms to help rule these out.

There is no single test that can be used to diagnose UC, so a combination of tests is usually required:

  • Blood tests help to rule out other medical conditions, and certain markers in the blood can indicate that inflammation is present.
  • A stool sample may find other possible causes of diarrhoea and inflammation, such as an infection.
  • A colonoscopy (orflexible sigmoidoscopy) may be performed, where a thin, flexible tube that contains a tiny camera looks inside the bowel for ulcers, inflammation and bleeding.
  • A biopsy (small sample of tissue) may be taken from inside the bowel so a pathologist can examine it under a microscope to look for signs of disease.

Other types of imaging (e.g. x-ray) are sometimes used to help in the diagnosis and to help rule out other diseases.

How is ulcerative colitis treated?

There is no known cure, but treatment is available to help minimise the impact of UC. Your doctor or specialist may also recommend a specific diet that suits your situation.


UC involves periods of 'relapse' when the inflammation in the bowel flares up, and periods of 'remission' when the inflammation calms down. The aim of treatment is to treat relapses when they occur and give the bowel a chance to heal. Medications also help maintain remission, improve general wellbeing and prevent complications from developing.

Medications commonly used to control inflammation in UC include:

You may also be advised to take medicines that control diarrhoea, relieve pain and supplement your diet (to boost your iron levels, vitamin D and calcium, for example).


If the UC is severe and does not respond to medication, your doctor may recommend surgery to remove the colon. A 'pouch' is then created inside the body using the end of the small intestine, and this pouch is connected directly to the anus.

Another option is to create a temporary or permanent stoma. This is an artificial opening in the stomach that diverts faeces into a bag. The surgery eliminates the symptoms of UC so medications are often no longer required.

It's normal to feel uneasy about the idea of living with a stoma, but it often greatly improves a person's quality of life.

Living with ulcerative colitis

With careful management, most people with UC are able to enjoy life, including work, travel, recreation, sex and having children.

To keep healthy, consider:

  • eating a nutritious diet to help with healing and reduce fatigue
  • keeping a food diary to check if there are any foods that make your symptoms worse during a flare-up
  • asking your doctor about supplements if you think you may be malnourished
  • exercising regularly to lift your mood and help relieve stress
  • learning some relaxation techniques to help manage stress

Complications of ulcerative colitis

A small number of people with colitis can develop inflammation in other parts of the body, such as the liver, skin, joints and eyes.

Regular monitoring by a gastroenterologist, as well as colonoscopies, may help prevent complications from developing. But medications, including steroids and drugs designed to prevent inflammation — and occasionally surgery — may be needed.

Osteoporosis (thinning of the bones) can develop as a side effect of long-term corticosteroid use.

Cases of marked inflammation caused by UC can also lead to:

  • nutritional deficiencies
  • weight loss
  • heavy bleeding due to deep ulcers
  • perforation (rupture) of the bowel
  • problems with the bile ducts, affecting the liver
  • fulminant colitis and toxic megacolon, conditions that cause the bowel to stop working

In the long-term, UC is associated with an increased risk of developing bowel cancer. After 10 years the risk of bowel cancer is 1 in 50, and after 20 years it increases to 1 in 12. This risk can be decreased by maintaining a healthy diet, exercising and avoiding alcohol and smoking.

Can you die from ulcerative colitis?

It's extremely rare to die from UC. Most people with UC eventually die from another cause. In most cases, UC can be managed throughout a person's life.

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Last reviewed: October 2020

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