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Ulcerative Colitis

What is Ulcerative Colitis

Ulcerative Colitis (UC) is a condition that causes inflammation and ulceration of the inner lining of the colon and rectum (the large bowel).  Inflammation is the body’s reaction to irritation, injury or infection, and can cause redness, swelling and pain.  In UC, ulcers develop on the surface of the bowel lining and these may bleed and produce mucus.  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 sometimes described as a chronic condition.  This means that it is ongoing and lifelong, although you may have long periods of good health known as remission, as well relapses or flare-ups when your symptoms are more active. Everyone is different - in many people the disease is mild with few flare-ups, while other people may have more severe disease.  At present there is no cure for Ulcerative Colitis.

How does Ulcerative Colitis affect the gut?

As you can see from the diagram, the gut, or digestive system, is 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, also known as the small bowel.  Here it is broken down even further so that the useful nutrients from food can be absorbed into the bloodstream through the wall of the intestine.  The waste products from this process - liquid and undigested parts of food - then pass into the colon, which is also known as the large intestine or large bowel.  The colon absorbs the liquid, and the leftover waste forms solid faeces (stools).  These collect in the last part of the colon and the rectum until they are pushed out of the body through the anus in a bowel movement.  In UC, parts of the colon and/or rectum become inflamed and sore.  Ulcers can develop on the colon lining and these can bleed or produce mucus. The inflamed colon is less able to absorb the liquid, and this can lead to a larger volume of watery stools.  Also, because the colon cannot hold as much waste as normal, very frequent bowel movements (six or more a day) may occur.

What are the main symptoms?

Ulcerative Colitis symptoms may range from mild to severe and vary from person to person.  They may also change over time, with periods of remission where you have good health and no symptoms, alternating with relapses or flare-ups, when your symptoms are troublesome.  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.  Your symptoms may vary according to how much of the colon is inflamed and how severe the inflammation is, but the most common symptoms during a flare-up are:

  • Diarrhoea: this is often with blood and mucus, and an urgent need to rush to the toilet

  • Cramping pains in the abdomen: these can be very severe and often occur before passing a stool

  • Tiredness and fatigue: this can be due to the illness itself, from anaemia (see below), or from a lack of sleep if you have to keep getting up at night with pain or diarrhoea

  • Feeling generally unwell: some people may have a raised temperature and feel feverish, with a fast heartbeat

  • Loss of appetite and loss of weight.

  • Anaemia (a reduced number of red blood cells): you are more likely to develop anaemia if you are losing a lot of blood or not eating well; anaemia can make you feel very tired.

How common is Ulcerative Colitis

It is estimated that Ulcerative Colitis affects about one in every 420 people in the UK.

UC is more common in urban than rural areas, and in northern developed countries - although the numbers are beginning to increase in developing nations.  UC is also more common in white Europeans, especially those of Ashkenazi Jewish descent (those who lived in Eastern Europe and Russia). UC affects women and men equally.

What causes Ulcerative Colitis

Although there has been much research, we still do not know exactly what causes Ulcerative Colitis.  However major advances have been made over the past few years, particularly in genetics.  Researchers now believe that Ulcerative Colitis is caused by a combination of factors:  Viruses, bacteria, diet and stress have all been suggested as environmental triggers, but there is no definite evidence that any one of these factors is the cause of UC. 

What are the main types of Ulcerative Colitis?

Ulcerative Colitis is generally categorised according to how much of the large intestine is affected.  The diagram shows the three main types: proctitis, left sided or distal colitis, and total or pancolitis.


In proctitis, only the rectum (the lowest part of the large bowel) is inflamed.  This means that the rest of the colon is unaffected and can still function normally.  For many people with proctitis, the main symptom is passing fresh blood, or bloodstained mucus.  You may get diarrhoea, or you may have normal stools or even constipation. You may also feel an urgent need to rush to the toilet. Because the inflamed rectum is more sensitive, some people with proctitis often feel that they have an urge to pass a stool but cannot pass anything as the bowel is actually empty. This is called tenesmus.  In some people, the sigmoid colon (the short curving piece of colon nearest the rectum) may also be inflamed – a form of UC sometimes known as proctosigmoiditis.  The symptoms are similar to those of proctitis, although constipation is less likely.

Left-sided (or distal) colitis

In this type of UC, the inflammation involves the distal colon, which includes the rectum and the left side of the colon (also known as the descending colon).  Symptoms include diarrhoea with blood and mucus, pain on the left side of the abdomen, urgency and tenesmus.

Total colitis/pancolitis

UC that affects the whole colon is known as total colitis or pancolitis. If the inflammation affects most of the colon, but not all of it, it is known as extensive colitis.  Extensive and total colitis can cause very frequent diarrhoea with blood, mucus, and sometimes pus (a thicker, more yellow fluid than mucus).  You may also have severe abdominal cramps and pain, tenesmus, fever and weight loss. In milder flare-ups, the main symptom may be diarrhoea or looser stools without blood. 

Can Ulcerative Colitis affect other parts of the body?

Ulcerative Colitis can cause problems outside the digestive system.  Over a third of people with UC develop other conditions, mainly affecting the joints, eyes and skin.  These are often referred to as extra intestinal manifestations (EIMs) and are most likely to occur during active disease.  However, they can also develop during times of remission, or even before any signs of bowel disease appear.


Inflammation of the joints, known as arthritis, affects about one in 10 people with UC.  The inflammation usually affects the large joints in the arms and legs, including elbows, wrists, knees and ankles.  Symptoms usually improve with treatment for UC and there is generally no lasting damage to the joints.  A few people develop swelling and pain in the smaller joints of the hands or feet, which may be longer lasting and persist even when the IBD is in remission.


UC can also cause skin problems.  A condition known as erythema nodosum affects about one in 10 people with UC. Its main symptom is painful red swellings, usually on the legs, that fade to a bruise-like mark.  This condition tends to occur during flare-ups and generally improves with treatment for the UC.  More rarely, people with UC may develop a condition known as pyoderma gangrenosum.  This starts as small tender blisters, which become painful, deep ulcers. These can occur anywhere on the skin, but most commonly appear on the shins or near stomas.  It is often treated by a dermatologist with topical therapy, but may need drug therapy with steroids, immunosuppressants or biologics.


Some people with UC develop inflammation of the eyes.  The most common condition is episcleritis, which affects the layer overlying the white of the eye, making it red, sore and inflamed.  Episcleritis tends to flare up at the same time as IBD and may need anti-inflammatory treatment; sometimes steroid drops are prescribed. Two other eye conditions linked with UC are uveitis, (inflammation of the iris) and scleritis (which affects the white outer coating of the eye).


People with UC are more at risk of developing thinner and weaker bones.  This can be due to the inflammatory process itself, poor absorption of the calcium needed for bone formation, low calcium levels from avoiding dairy foods or the use of steroid medication. Smoking also increases this risk.


About one in 25 people with UC get sores or ulcers in the mouth, usually when the condition is more active.


Some people with UC develop liver inflammation.  A condition called Primary Sclerosing Cholangitis (PSC) affects up to one in 25 people with UC. PSC causes inflammation of the bile ducts and can eventually affect the liver cells.

Could my symptoms be IBS?

Irritable Bowel Syndrome (IBS) is a different condition from IBD, although some of the symptoms are similar.  Like IBD, IBS can cause abdominal pain, bloating and bouts of diarrhoea or constipation.  However, it does not cause the type of inflammation typical of UC, and there is no blood loss with IBS.  Some people with UC may develop IBS-like symptoms, for example experiencing diarrhoea even when their IBD is inactive.  These symptoms may need slightly different treatment from their usual IBD symptoms.  IBS is more common in people with IBD than in the general population.

Can Ulcerative Colitis lead to bowel cancer?

Ulcerative Colitis is not a form of cancer.  However, if you have had UC for many years, you have a greater risk than normal of developing cancer in the colon or rectum.  This risk increases with the extent of the colon affected by UC, and so is greater if you have extensive colitis than left-sided colitis.  People with proctitis have no increased risk. Research shows that the risk of developing cancer usually begins to increase about 8-10 years after the start of the IBD symptoms.

What treatments are there for Ulcerative Colitis?

Ulcerative Colitis can often be managed by medication (drug treatment), but surgery may become necessary if the inflammation is very severe, and in some other situations.  Your treatment will depend on the type and severity of your UC, and the choices you make in discussion with your doctor.

What drugs are used to treat Ulcerative Colitis?

Drug treatment for UC aims to reduce symptoms and control flare-ups, and then maintain remission once the disease is under control.  This can mean that you need to take your medication on an ongoing basis, sometimes for many years.  It is less likely that you will need only a short course of drugs.  However, if your condition is mild and limited to a small part of your colon, you may be able to stop treatment on advice from your doctor if you have been free of symptoms for a few years, and an endoscopy shows disease healing in the gut.

The main types of drugs

The aim of drug treatment for Ulcerative Colitis is to reduce inflammation.  The main types of drugs are:

  • Aminosalicylates (5-ASAs) reduce inflammation in the lining of the intestine. Examples include mesalazine (brand names include Asacol, Ipocol, Octasa, Pentasa, and Salofalk), olsalazine (Dipentum), sulphasalazine (Salazopyrin) and   balsalazide (Colazide).

  • Corticosteroids (steroids) work by blocking the substances that trigger allergic and inflammatory responses in your body. They include prednisolone, prednisone, methylprednisolone, budesonide (Entocort Budenofalk)), hydrocortisone and beclometasone dipropionate (Clipper).

  • Immunosuppressants suppress the immune system and reduce levels of inflammation. The main immunosuppressants used in IBD are azathioprine (Imuran), mercaptopurine or 6MP (Purinethol), methotrexate, ciclosporin and tacrolimus. They are often used in patients who relapse when they come off steroids.

  • Biological drugs are the newest group of drugs used to treat IBD. Anti-TNF drugs, such as infliximab (Remicade, Remsima, Inflectra), adalimumab (Humira) and golimumab (Simponi) target a protein in the body called TNF, or tumor necrosis factor, preventing inflammation. Another type of biological drug is vedolizumab (Entyvio), which works by stopping white blood cells from entering the lining of the gut and causing inflammation.

Do I need to change my diet?

There has been extensive research into the role of diet in Ulcerative Colitis, but so far there is little evidence that any particular food or additive can cause or improve UC.

Generally, the most important thing is to eat a nutritious and balanced diet to maintain your weight and strength, and to drink enough fluids to prevent you from becoming dehydrated.  Even so, you may find that certain foods affect your symptoms. For example, when you have a flare-up, bland, soft foods may cause less discomfort than raw vegetables or spicy foods.  You may also find that eating too much fibre can increase the urge to go to the toilet.

The urge to open the bowels is usually caused by inflammation in the lower colon, but, as fibre adds bulk to faeces, it can act as a trigger and make the urgency worse.  So, it may be helpful during flare-ups to reduce the amount of fibre you eat and perhaps go on a low-fibre diet.  Once the flare-up is over, you should try to increase your intake of fibre again.  Fibre is useful because it keeps the colon healthier as well as providing fuel for beneficial bacteria. Some people with UC have noticed that dairy products trigger their symptoms - although research suggests that, in general, people with UC are no more likely to be lactose intolerant than the general population.  Because milk and dairy products are an important food group, it is better not to give them up until you have spoken to your IBD team.

What about complementary and alternative approaches?

Some people with Ulcerative Colitis find complementary and alternative medicines help their symptoms.  Examples include acupuncture, wheatgrass juice, aloe vera gel, omega 3 fish oils and faecal microbiota transplantation.  Many of these supplements and treatments are still being researched, and although they may help some people, there is no conclusive evidence about when or how they will work.

Everyone is different, and what may help one person may not work, or even have a harmful effect, on another.  It is possible that people who benefit from such treatments might have gone into remission coincidentally, given the unpredictable course of Ulcerative Colitis.  They could also be experiencing a placebo effect, where their symptoms improve simply because they believe the treatment will work.

Does Ulcerative Colitis run in families?

Ulcerative Colitis tends to run in families, and parents with IBD are slightly more likely to have a child with IBD. However, studies show for most people the actual risk is relatively small.  If one parent has UC, the risk of their child developing IBD is about 2% - that is, for every 100 people with UC having a child, about two of the children may be expected to develop IBD at some time in their lives.  This risk is higher if both parents have IBD. However, we still cannot predict exactly how UC is passed on.  Even with genetic predisposition, additional factors are needed to trigger IBD.

Ulcerative Colitis (UC) is a condition that causes inflammation and ulceration of the inner lining of the colon and rectum (the large bowel).  Inflammation is the body’s reaction to irritation, injury or infection, and can cause redness, swelling and pain.

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