Ulcerative colitis


Ulcerative colitis


Ulcerative colitis is a long-term condition, where the colon and rectum become inflamed.

The colon is the large intestine (bowel), and the rectum is the end of the bowel where stools are stored.

Small ulcers can develop on the colon's lining, and can bleed and produce pus.

Symptoms of ulcerative colitis

The main symptoms of ulcerative colitis are:

recurring diarrhoea, which may contain blood, mucus or pus

abdominal (tummy) pain

needing to empty your bowels frequently

The severity of the symptoms varies, depending on how much of the rectum and colon is inflamed and how severe the inflammation is. For some people, the condition has a significant impact on their everyday lives.

Some may go for weeks or months with very mild symptoms, or none at all (known as remission), followed by periods where the symptoms are particularly troublesome (known as flare-ups or relapses).

When to seek medical advice

You should see your GP as soon as possible if you have symptoms of ulcerative colitis and you haven't been diagnosed with the condition. They can arrange blood or stool sample tests to help determine what may be causing your symptoms. If necessary, they can refer you to hospital for further tests.

If you have been diagnosed with ulcerative colitis and think you may be having a severe flare-up, contact your GP or care team for advice. You may need to be admitted to hospital.

What causes ulcerative colitis?

Ulcerative colitis is thought to be an autoimmune condition. This means the immune system – the body’s defence against infection – goes wrong and attacks healthy tissue.

The most popular theory is that the immune system mistakes harmless bacteria inside the colon for a threat and attacks the tissues of the colon, causing it to become inflamed.

Exactly what causes the immune system to behave in this way is unclear. Most experts think it is a combination of genetic and environmental factors.


Who is affected

It is estimated that around 1 in every 420 people living in the UK has ulcerative colitis; this amounts to around 146,000 people.

The condition can develop at any age, but is most often diagnosed between 15 and 25.

It's more common in white people of European descent (especially those descended from Ashkenazi Jewish communities) and black people. The condition is rarer in people of Asian background (although the reasons for this are unclear).

Both men and women seem to be equally affected by ulcerative colitis.

How ulcerative colitis is treated

Treatment for ulcerative colitis aims to relieve symptoms during a flare-up and prevent symptoms from returning (known as maintaining remission).  

In most people, this is achieved by taking medication such as aminosalicylates (ASAs) and corticosteroids.

Mild to moderate flare-ups can usually be treated at home. However, more severe flare-ups need to be treated in hospital to reduce the risk of serious complications, such as gas becoming trapped inside the colon, which can lead to swelling.

If medications are ineffective at controlling your symptoms, or your quality of life is significantly affected by your condition, surgery to remove your colon may be an option.

During surgery, your small intestine will either be diverted out of an opening in your abdomen (known as an ileostomy), or it will be used to create an internal pouch that is connected to your anus (known as an ileo-anal pouch).

Symptoms of ulcerative colitis 

The symptoms of ulcerative colitis vary depending on how much of the rectum and colon is inflamed, and how severe the inflammation is.

The most common symptoms are:

recurring diarrhoea, which may contain blood, mucus or pus

abdominal (tummy) pain

needing to empty your bowels frequently

You may also experience fatigue (extreme tiredness), loss of appetite and weight loss.

You may go for weeks or months with very mild or no symptoms (remission), followed by periods where the symptoms are particularly troublesome (known as flare-ups or relapses).

No specific trigger for flare-ups has been identified, although stress is thought to be a potential factor.

Additional symptoms

During a flare-up, some people with ulcerative colitis also experience symptoms not related to the inflammation in their bowels.

For example, some people develop painful and swollen joints (arthritis),mouth ulcers, areas of painful, red and swollen skin, or irritated and red eyes.

Symptoms of a severe flare-up

A severe flare-up is defined as having to empty your bowels six or more times a day, as well as having additional symptoms such as shortness of breath, a fast or irregular heartbeat, or a high temperature (fever).

You may also notice that any blood in your stools becomes much more obvious.

When to seek medical advice

You should see your GP if you have symptoms of ulcerative colitis and you haven't been diagnosed with the condition.

If you think you may be having a severe flare-up, contact your GP or care team (if you have already been diagnosed with ulcerative colitis) for advice. You may need to be admitted to hospital as a precaution.


Causes of ulcerative colitis 

The exact cause of ulcerative colitis is unknown, although it is thought to be the result of a problem with the immune system.

Autoimmune condition

The immune system is the body's defence against infection. Many experts believe that ulcerative colitis is an autoimmune condition (when the immune system mistakenly attacks healthy tissue).

The immune system normally fights off infections by releasing white blood cells into the blood to destroy the cause of the infection. This results in inflammation (swelling and redness) of body tissue in the infected area.

In ulcerative colitis, a leading theory is that the immune system mistakes "friendly bacteria" in the colon – which aid digestion – as a harmful infection, leading to the colon and rectum becoming inflamed.

Alternatively, some researchers believe a viral or bacterial infection triggers the immune system, but for some reason it doesn't "turn off" once the infection has passed and continues to cause inflammation.

It has also been suggested that no infection is involved, and the immune system may just malfunction by itself.


It also seems inherited genes are a factor in the development of ulcerative colitis. Studies have found that more than one in four people with ulcerative colitis has a family history of the condition.

Levels of ulcerative colitis are also a lot higher in certain ethnic groups, further suggesting that genetics are a factor.

Researchers have identified several genes that seem to make people more likely to develop ulcerative colitis, and it is believed that many of these genes play a role in the immune system.

Environmental factors

Where and how you live also seems to affect your chances of developing ulcerative colitis, suggesting that environmental factors are important.

For example, the condition is more common in urban areas of northern parts of Western Europe and America.

Various environmental factors that may be linked to ulcerative colitis have been studied, including air pollution and certain diets, but no factors have so far been identified.

Diagnosing ulcerative colitis 

To diagnose ulcerative colitis, your GP will first ask about your symptoms, general health and medical history.

They will also physically examine you, checking for signs such as paleness (caused by anaemia) and tenderness in your tummy (caused by inflammation).

A stool sample can be checked for signs of infection, as gastroenteritis(infection of the stomach and bowel) can sometimes have similar symptoms to ulcerative colitis. Blood tests may also be carried out to check for anaemia and to see if there is inflammation on any part of your body.

Further tests

If your GP suspects you may have inflammatory bowel disease (a term mainly used to describe two diseases: ulcerative colitis or Crohn's disease), you may be referred to hospital for further tests. These could include an X-ray and a detailed examination of your rectum and colon.

The two types of examination you may have are described below.


A diagnosis of ulcerative colitis can be confirmed by examining the level and extent of bowel inflammation. This is initially done by using a sigmoidoscope, which is a flexible tube containing a camera that is inserted into your rectum (bottom).

A sigmoidoscopy can also be used to remove a small sample of tissue from your bowel, so it can be tested in a laboratory. This is known as abiopsy.

The procedure is not painful, but it can be uncomfortable, and you can be given a sedative to help you relax. It usually takes around 15 minutes and you can often go home the same day.

A sigmoidoscope is only capable of looking at the rectum and lower part of the colon. If it is thought your ulcerative colitis has affected more of your colon, another examination will be required. This is known as a colonoscopy.


A colonoscopy uses a longer and more flexible tube called the colonoscope, which allows your entire colon to be examined. As with a sigmoidoscope, a colonoscope can also be used to obtain a biopsy sample.

Before having a colonoscopy, your colon needs to be completely empty. Therefore, you will need to take strong laxatives beforehand.

A colonoscopy is not painful, but you may feel some initial discomfort. You will be given sedatives to help you relax. The procedure takes around half an hour, after which you will be able to go home.

Treating ulcerative colitis 

Treatment for ulcerative colitis depends on how severe the condition is and how often your symptoms flare up.

The main aims of treatment are to:

reduce symptoms, known as inducing remission (a period without symptoms)

maintain remission

This will usually involve taking various types of medication, although surgery may sometimes be an option.

Your treatment will normally be provided by a range of healthcare professionals, including specialist doctors (such as gastroenterologists or surgeons), GPs and specialist nurses.

Your care will often be co-ordinated by your specialist nurse and your care team, and they will usually be your main point of contact if you need help and advice.


Aminosalicylates (ASAs), such as sulphasalazine or mesalazine, are medications that help to reduce inflammation. They are usually the first treatment option for mild or moderate ulcerative colitis.

ASAs can be used as a short-term treatment to treat flare-ups. They can also be taken long term, usually for the rest of your life, to maintain remission.

ASAs can be taken:

orally – by swallowinga tablet or capsule

as a suppository – a capsule that you insert into your rectum (bottom), where it then dissolves

through an enema – where fluid is pumped into your large intestine

How you take ASAs will depend on the severity and extent of your condition.

The side effects of ASAs can include headaches, feeling sick,diarrhoea, abdominal (tummy) pain and a rash.


Corticosteroids, such as prednisolone, are a more powerful type of medication used to reduce inflammation. They can be used with or instead of ASAs to treat a flare-up if ASAs alone are not effective.

Like ASAs, steroids can be administered orally, or through a suppository or enema.

However, unlike ASAs, corticosteroids are not used as a long-term treatment to maintain remission because they can cause potentially serious side effects, such as osteoporosis (weakening of the bones) and cataracts (cloudy patches in the lens of the eye) when used for a long time.

Side effects of short-term steroid use can include acne, increased appetite, mood changes (such as becoming more irritable) and mood swings.


Immunosuppressants, such as tacrolimus and azathioprine, are medications that reduce the activity of the immune system. They are usually given as tablets to treat mild or moderate flare-ups, or maintain remission if your symptoms haven't responded to other medications.

Immunosuppressants can be very effective in treating ulcerative colitis, but they often take a while to start working (usually between two and three months).

The medicines can make you more vulnerable to infection, so it is important to report any signs of infection, such as fever or sickness, promptly to your GP.

They can also lower the production of red blood cells, making you prone to anaemia. You will need regular blood tests to monitor your blood cell levels and to check for any other problems.

Treating severe flare-ups

While mild or moderate flare-ups can usually be treated at home, more severe flare-ups should be managed in hospital to minimise the risk ofdehydration, malnutrition and potentially fatal complications, such as your colon rupturing.

In hospital, you will be given medication and fluids intravenously (directly into a vein). The medication you have will usually be a type of corticosteroid or an immunosuppressant medication called ciclosporin.

If ciclosporin is also unsuitable, you may be given a medication called infliximab.


Ciclosporin works in the same way as other immunosuppressant medications (see above) – by reducing the activity of the immune system. However, it is more powerful than the medications used to treat milder cases of ulcerative colitis and starts to work much sooner (normally within a few days).

Ciclosporin is given slowly through a drip in your arm (known as an infusion) and treatment will usually be continuous, for around seven days.

Side effects of intravenous ciclosporin can include:

a tremor (an uncontrollable shaking or trembling of part of the body)

excessive hair growth

fatigue (extreme tiredness)

swollen gums

feeling and being sick


Ciclosporin can also cause more serious problems such as high blood pressure and reduced kidney and liver function, but you will be monitored regularly during treatment to check for signs of these.


Infliximab is a type of medication that works by targeting a protein called TNF-alpha, which the immune system uses to stimulate inflammation.

Infliximab is given as an infusion over the course of two hours. You will be given further infusions after two weeks, and again after six weeks. Infusions are then given every eight weeks, if treatment is still required.

Common side effects of infliximab can include:

increased risk of infection – report any symptoms of a possible infection, such as coughs, high temperature or sore throat, to your GP

vertigo (the sensation you or the environment around you is moving) and dizziness

an allergy-like reaction, causing breathing difficulties, urticaria(hives) and headaches

In most cases, a reaction to the medication occurs in the first two hours after the infusion has finished. However, some people experience delayed reactions days, or even weeks, after an infusion. If you begin to experience the symptoms listed above after having infliximab, seek immediate medical assistance.

You will be carefully monitored after your first infusion and, if necessary, powerful anti-allergy medication, such as epinephrine, may be used.

Infliximab is not usually suitable for people with a history of tuberculosis (TB) or hepatitis B, because there have been a number of cases where infliximab has "reactivated" dormant infections. The medication is also not recommended for people with a history of heart disease.


If you have frequent flare-ups that have a significant effect on your quality of life, or you have a particularly severe flare-up that isn't responding to medication, surgery may be an option.

Surgery for ulcerative colitis involves permanently removing the colon (known as a colectomy).

During the operation, your small intestine will be used to pass waste products out of your body instead of your colon. This can be achieved by creating:

an ileostomy – where the small intestine is diverted out of a hole made in your abdomen. Special bags are placed over this opening, to collect waste materials after the operation

an ileo-anal pouch – where part of the small intestine is used to create an internal pouch that is then connected to your anus, allowing you to pass stools normally

Ileo-anal pouches are increasingly used because an external bag to collect waste products is not required.

As the colon is removed, ulcerative colitis cannot recur after surgery. However, it's important to consider the risks of surgery and the impact of having a permanent ileostomy or ileo-anal pouch.

Complications of ulcerative colitis 

If you have ulcerative colitis, you could develop further problems.

Some of the main complications of ulcerative colitis are described below.


People with ulcerative colitis are at an increased risk of developing osteoporosis, when the bones become weak and are more likely to fracture.

This is not directly caused by ulcerative colitis, but can develop as a side effect of the prolonged use of corticosteroid medication. It can also be caused by the dietary changes someone with the condition may take – such as avoiding dairy products, if they believe it could be triggering their symptoms.

If you are thought to be at risk of osteoporosis, the health of your bones will be regularly monitored. You may also be advised to take medication or supplements of vitamin D and calcium to strengthen your bones.


Poor growth and development

Ulcerative colitis, and some of the treatments for it, can affect growth and delay puberty.

Children and young people with ulcerative colitis should have their height and body weight measured regularly by healthcare professionals. This should be checked against average measurements for their age.

These checks should be carried out every 3-12 months, depending on the person's age, the treatment they are having and the severity of their symptoms.

If there are problems with your child's growth or development, they may be referred to a paediatrician (a specialist in treating children and young people).

Primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC), where the bile ducts become progressively inflamed and damaged over time, is a common complication of ulcerative colitis. Bile ducts are small tubes used to transport bile (digestive juice) out of the liver and into the digestive system.

PSC does not usually cause symptoms until it's at an advanced stage. Symptoms can include:

fatigue (extreme tiredness)


itchy skin

weight loss


a high temperature (fever)

yellowing of the skin and the whites of the eyes (jaundice)

There is currently no specific treatment for PSC, although medications can be used to relieve some of the symptoms, such as itchy skin. In more severe cases, a liver transplant may be required.

Toxic megacolon

Toxic megacolon is a rare and serious complication of severe ulcerative colitis, where inflammation in the colon causes gas to become trapped, resulting in the colon becoming swollen.

This is potentially very dangerous as it can send the body into shock (causing a sudden drop in blood pressure), the colon could rupture (split), or cause infection in the blood (septicaemia).

The symptoms of a toxic megacolon include:

abdominal (tummy) pain

a high temperature (fever)

a rapid heart rate

Toxic megacolon can be treated with fluids, antibiotics and steroids given intravenously (directly into a vein). A tube will also need to be inserted into your rectum and colon so the gas can be drawn out. In more severe cases, surgical removal of the colon (known as a colectomy) may be needed.

Treating symptoms of ulcerative colitis before they become severe can help prevent toxic megacolon.

Bowel cancer

People who have ulcerative colitis have an increased risk of developing bowel cancer (cancer of the colon, rectum or bowel), especially if the condition is severe or extensive. The longer you have ulcerative colitis, the greater the risk.

People with ulcerative colitis are often unaware they have bowel cancer as the initial symptoms of this type of cancer are similar. These include blood in the stools, diarrhoea and abdominal pain.

Therefore, you will usually have regular check-ups to look for signs of bowel cancer from about 10 years after your symptoms first develop.

Check-ups will involve examining your bowel with a colonoscope – which is a long, flexible tube containing a camera – that is inserted into your rectum. The frequency of the colonoscopy examinations will increase the longer you live with the condition, and will also depend on factors such as how severe your ulcerative colitis is and if you have a family history of bowel cancer.

To reduce the risk of bowel cancer, make sure you eat a healthy, balanced diet including plenty of fresh fruit and vegetables. It is also important to take regular exercise, maintain a healthy weight and avoid alcohol and smoking.

Taking aminosalicylates as prescribed should also help reduce your risk of bowel cancer.

Living with ulcerative colitis 

There are a few things you can do to help keep symptoms under control and reduce your risk of complications.

Dietary advice

Although particular diets are not thought to play a role in causing ulcerative colitis, some changes to your diet can help control the condition.

For example, you may find it useful to:

eat small meals – eating five or six smaller meals a day, rather than three main meals, may help control your symptoms

drink plenty of fluids – it is easy to become dehydrated when you have ulcerative colitis, as you can lose a lot of fluid through diarrhoea. Water is the best source of fluids. Avoid caffeine and alcohol – as these will make your diarrhoea worse – and fizzy drinks, which can cause flatulence (gas)

take food supplements – ask your GP or gastroenterologist if you need food supplements, as you might not be getting enough vitamins and minerals in your diet

Keep a food diary

Keeping a food diary that documents what you eat can also be helpful. You may find you can tolerate some foods while others make your symptoms worse. By keeping a record of what and when you eat, you should be able to identify problem foods and eliminate them from your diet.

However, you should not eliminate entire food groups (such as dairy products) from your diet without speaking to your care team, because you may not get enough of certain vitamins and minerals.

If you want to try a new food, it's best to only try one type a day, as it's then easier to spot foods that cause problems.

Low-residue diet

Temporarily eating a low-residue or low-fibre diet can sometimes help improve symptoms of ulcerative colitis during a flare-up. These diets are designed to reduce the amount and frequency of the stools you pass.

Examples of foods that can be eaten as part of a low-residue diet include:

white bread

refined (non-wholegrain) breakfast cereals, such as cornflakes

white rice, refined pasta and noodles

cooked vegetables (but not the peel, seeds or stalks)

lean meat and fish


If you are considering trying a low-residue diet, make sure you talk to your care team first.

Stress relief

Although stress does not cause ulcerative colitis, successfully managing stress levels may reduce the frequency of symptoms. The following advice may help:

exercise – this has been proven to reduce stress and boost your mood. Your GP or care team can advise on a suitable exercise plan

relaxation techniques – breathing exercises, meditation and yogaare good ways of teaching yourself to relax

communication – living with ulcerative colitis can be frustrating and isolating. Talking to others with the condition can help (see below)


Emotional impact

Living with a long-term condition that is as unpredictable and potentially debilitating as ulcerative colitis can have a significant emotional impact.

In some cases, anxiety and stress caused by ulcerative colitis can lead to depression. Signs of depression include feeling very down, hopeless and no longer taking pleasure in activities you used to enjoy. If you think you might be depressed, contact your GP for advice.

You may also find it useful to talk to others affected by ulcerative colitis, either face-to-face or via the internet. A good resource is the Crohn's and Colitis UK website, which has details of local support groups and contains a large range of useful information on ulcerative colitis and related issues.



The chances of a woman with ulcerative colitis becoming pregnant are not usually affected by the condition. However, infertility can be a complication of surgery carried out to create an ileo-anal pouch.

This risk is much lower if you have surgery to divert the small intestine through an opening in your abdomen (an ileostomy).

Certain types of aminosalicylate (ASA) medication can lead to a temporary loss of fertility in men, but alternative medications are available.


The majority of women with ulcerative colitis who decide to have children will have a normal pregnancy and a healthy baby.

However, if you are pregnant or planning a pregnancy you should discuss it with your care team. If you become pregnant during a flare-up, or have a flare-up while pregnant, there is a risk you could give birth early (premature birth) or have a baby with a low birthweight.

For this reason, doctors usually recommend trying to get ulcerative colitis under control before getting pregnant.

Most ulcerative colitis medications can be taken during pregnancy, including corticosteroids, most ASAs and some types of immunosuppressant medication.

However, there are certain medications (such as some types of immunosuppressant) that may need to be avoided as they are associated with an increased risk of birth defects.

In some cases, you may be advised to take a medication that is not normally recommended during pregnancy if your doctors think the risks of taking the medication outweigh the risks of having a flare-up.

Ulcerative colitis