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What is UC?

UC is a condition that causes inflammation and ulceration of the inner lining of the rectum and colon (the large bowel). Tiny ulcers develop on the surface of the lining and these may bleed and produce pus.

The inflammation usually begins in the rectum and lower colon, but it may affect the entire colon. If UC only affects the rectum, it is called proctitis.

UC is one of the two main forms of Inflammatory Bowel Disease, so may also be called “IBD”. The other main form of IBD is Crohn’s Disease.

UC is sometimes described as a chronic condition. This means that it is ongoing and life-long, although you may have long periods of good health (remission), as well as times when your symptoms are more active (relapses or flare-ups).

What causes UC?

Although considerable progress has been made in IBD research, researchers do not yet know what causes this disease. Studies indicate that the inflammation in IBD involves a complex interaction of factors: the genes the person has inherited, the immune system, and something in the environment.

How does UC affect the gut?

The gut (digestive system) is like a long tube that starts at the mouth and ends at the anus. When we eat, the food goes down the oesophagus into the stomach, where gastric (digestive) juices break it down to a porridge-like consistency. The partly-digested food then moves into the small intestine (small bowel). Here it is broken down even further so that nutrients can be absorbed into the bloodstream through the wall of the intestine. The waste products from this process – liquid and undigested parts of food – are then pushed into the colon (large intestine/large bowel). The colon absorbs the liquid, and the left over waste forms solid faeces (stools). These collect in the last part of the colon and the rectum until they are passed out of the body in a bowel movement.

In UC, parts of the colon and/or rectum become inflamed and sore. Tiny ulcers can develop on the colon lining and these can bleed or produce pus.

The inflamed colon is less able to absorb liquid and this can lead to a larger volume of watery stools. Also, because the colon cannot hold as much as usual, you may have very frequent bowel movements (six or more a day).

What are the main symptoms?

UC symptoms may range from mild to severe and will vary from person to person.

They may also change over time, with periods of good health when you have few or no symptoms (remission), alternating with times when your symptoms are more active (flare-ups).

UC is a very individual condition – some people can remain well for a long time, even for many years, while others have frequent flare-ups.

Symptoms may vary according to the extent and severity of the inflammation, but the most common symptoms during a flare-up are:

• Diarrhoea. This is often with blood, mucus and pus.
• Stomach cramps. These can be very severe and often occur before passing a stool.
• Tiredness and fatigue. This can be due to the illness itself or from anaemia.
• Feeling feverish.
• Loss of appetite and loss of weight.
• Anaemia. You are more likely to develop anaemia if you are losing a lot of blood.

see Tests and Investigations for information on how Ulcerative Colitis is diagnosed.

see Medication used in IBD for information on what drugs are used in Ulcerative Colitis.

see Surgery for Ulcerative Colitis for information on surgery for Ulcerative Colitis.

© Crohn’s and Colitis UK 2015