Ulcerative colitis | Mate kōpiro nui

Ulcerative colitis (mate kōpiro nui) is a type of inflammatory bowel disease that causes swelling and ulcers in the innermost lining of the large intestine (colon).

Key points

  1. Ulcerative colitis is an ongoing condition and symptoms usually develop over time, rather than suddenly.
  2. The most common symptoms are bloody diarrhoea and lower abdominal pain.
  3. Ulcerative colitis may occur at any age, but it is most common in young adults in the 15 to 30 year age group or later on, in the 50 to 70 year age group. Women are more commonly affected than men. 
  4. Diagnosis of ulcerative colitis normally requires endoscopic examination and biopsy tests.
  5. Treatment is usually with anti-inflammatory drugs (usually tablets) and dietary modifications. Severe cases that do not respond to treatment may require surgery.

What does the colon do?

The large intestine, or colon, is the final part of our digestive system. By the time food has passed through the six and a half metres of your small intestine and reaches your colon, most of the food has been absorbed and only waste products are left. It is the job of the colon to absorb the excess water, as well as some fibre and potassium, from the waste and move the waste to the rectum. This becomes your bowel motion.

Inflammatory bowel disease (IBD) is a medical term used to describe a group of conditions in which the intestine become inflamed (red and swollen). There are two major types of IBD:

  • Crohn's disease which can occur in any part of the intestine. 
  • Ulcerative colitis which only affects the large intestine (colon).

People with ulcerative colitis have a higher chance of getting cancer of the colon, especially if the disease begins before the age of 15 or continues for longer than 10 years.

What are the causes of ulcerative colitis?

The exact cause of ulcerative colitis is unknown. The following have been suggested:

  • Immune system
    • Ulcerative colitis is thought to be a type of autoimmune disease, in which the body's immune system (defence system) malfunctions and attacks the tissues of the bowel.
  • Genetics
    • Ulcerative colitis seems to occur more in some families but it is not clear whether it is due to hereditary or environmental factors.
  • Diet
    • Some foods can make symptoms worse but this is on an individual basis with no specific foods being common to all people with the disease.
  • Stress
    • Some people find their symptoms are worse during periods of high stress, but flare-ups are just as likely to occur after a bout of the flu.

Ulcerative colitis may occur at any age, but it is most common in young adults in the 15-30 age group or later on, in the 50-70 age group. Women are affected more than men.

What are the symptoms of ulcerative colitis?

Most cases of ulcerative colitis are mild, but once symptoms are identified it is important to receive prompt medical attention because the condition can progress very quickly.

  • The main symptoms are frequent episodes of bloody diarrhoea (runny poos with blood and mucous) and pain in the lower abdomen (tummy area). This is combined with periods with no symptoms at all.
  • Most often an attack begins slowly and with mild symptoms such as an increased urgency to have a bowel motion, mild lower abdominal cramps, and blood and mucus appearing in the bowel motions. Pus may be present.
  • Other symptoms include weight loss, fever, dry mouth, sunken eyes, a fast heart beat and pale skin. Loss of appetite, nausea and vomiting can occur. There may be some difficulty controlling bowel motions and it may feel that the bowel has not emptied properly.
  • When you are examined by a doctor the bowel near to your anus will most likely be inflamed.

How is ulcerative colitis diagnosed?

Ulcerative colitis is diagnosed through a medical history, a physical examination, imaging tests to look at the bowel and laboratory tests.

  • Blood samples will be taken for testing and specimens of your bowel motions will be sent to the laboratory for examination to rule out an infectious cause of the colitis.
  • Your doctor will probably arrange a test on your lower bowel called a sigmoidoscopy. A narrow tube containing a camera and a light is passed through your anus into the lower bowel. This allows a specialist to look at the lining of your colon. Sometimes a small piece of tissue is removed (biopsy) so it can be examined more closely in a laboratory.
  • Another procedure called a colonoscopy may also be carried out. This allows a higher part of your colon to be examined.
  • In addition, a barium enema is sometimes necessary to see how far the inflammation has spread. A barium enema is an x-ray procedure which involves feeding barium-containing paste-like dye into the bowel through the anus. A series of x-rays are then taken which show the inside walls of the bowel.

These tests may be a bit uncomfortable but they are not usually painful.

What are the treatment options for ulcerative colitis?

The main aim of treatment for ulcerative colitis is to stop inflammation in the colon, to prevent flare-ups and to keep you in remission. The kind of treatment depends on the type of symptoms and how bad they are.


Medications are used to control the inflammation in your colon and to reduce your body’s immune response. Often medications are prescribed in a ‘stepped’ approach, depending on your response – beginning with fairly safe medications with few risks or side effects for moderate symptoms, and progressing to stronger medications with additional risks and side effects, for severe symptoms. The main groups of medicines to treat inflammation in ulcerative colitis are:

  • Gut-specific anti-inflammatories 
    • Known as aminosalicylates, these medications are often the treatment option for mild-to-moderate symptoms.
    • Examples include mesalazine, which may be given by mouth (as tablets or capsules), or by enema or suppository through the rectum (back passage), for mild flare-ups confined to the lower large intestine.
    • Other examples include olsalazine and sulfasalazine
  • Steroids
    • These are used to treat sudden flare-ups and is not usually continued once the flare-ups have settled.
    • Examples include budesonide, prednisone and methylprednisone which are given as tablets or capsules, to be taken by mouth, or hydrocortisone which is given as an enema.
  • Immunosuppressants
    • These are prescribed when symptoms usually do not respond to mesalazine.  
    • Examples include methotrexate, azathioprine and ciclosporin. 
  • Biologics (TNF inhibitors)
    • TNF inhibitors are used in severe ulcerative colitis, in patients who do not respond to other medications, or in people who have a fistula.
    • Examples include infliximab and adalimumab. 

Read more about the medications used for ulcerative colitis.

Nutrition and diet

Although diet does not cause ulcerative colitis, there may be times when changes in your eating habits may help control your symptoms and prevent flare-ups.  You may find it helpful to keep a diary of your daily food and drink intake to see which foods may be making your colitis symptoms worse. Useful tips are:

  • Avoid spicy foods or oily, fatty foods. 
  • Limit raw fruits and vegetables to limit abrasion to the inflamed lining of the colon, and this may result in reduced symptoms. 
  • Try limiting milk or other dairy products. A milk-free diet may also decrease symptoms in some patients, but it need not be continued if no benefit is noticed.
  • Reduce intake of sugary carbonated drinks (fizzy drinks), caffeine, and alcohol.
  • Try eating small meals more frequently rather than large meals. 

When you are well, there is no reason to avoid certain foods and it is important to eat a full and varied diet.


Mild to moderate ulcerative colitis does not usually require hospital treatment. Severe ulcerative colitis, or disease that does not respond to drug treatment, may mean that an operation to remove the colon is necessary. Nearly one-third of all patients with extensive ulcerative colitis ultimately require surgery. When performed in time, removal of the colon stops the symptoms of ulcerative colitis. Normal life expectancy and quality of life are restored.

Learn more

Ulcerative colitis Mayo Foundation for Medical Education and Research, 2014
Inflammatory bowel disease (IBD) Mayo Foundation for Medical Education and Research, 2014
Ulcerative colitis – causes, symptoms, treatment Southern Cross Healthcare Group NZ, 2013
Ulcerative Colitis – a patient's guide Family Doctor NZ, 2015
Ulcerative Colitis gastro-info NZ, Dr Alan Fraser
Inflammatory bowel disease – a focus on Crohn’s disease and ulcerative colitis Best Practice Journal, NZ, 2020

Credits: Editorial team. Reviewed By: Dr Derek JY Luo, MBChB (Otago) FRACP, Consultant Gastroenterologist Last reviewed: 23 Sep 2016