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Ulcerative Colitis (UC)

Written by Ada’s Medical Knowledge Team

Updated on

What is ulcerative colitis (UC)?

Ulcerative colitis (UC) is one of the two main forms of inflammatory bowel disease (IBD). The other is Crohn’s disease. Ulcerative colitis is a fairly common condition: approximately 907,000 people in the U.S. are believed to be affected. 1

The term colitis refers specifically to inflammation in the colon, or large intestine. In UC, inflammation occurring in the colon and/or rectum causes small ulcers to develop on the lining of the affected area, which may bleed and produce pus. Over time, the inflammation can permanently damage the mucosal (top) and submucosal (second) layers of intestinal tissue that line the colorectal area. This results in a variety of intestinal symptoms, including diarrhea and cramping. In addition, UC may also lead to problems in other body systems, either as a direct result of intestinal dysfunction, or due to more widespread effects of inflammation.

Ulcerative colitis is a lifelong (chronic) condition which requires regular medical attention. After diagnosis, a person may need to adapt their lifestyle to accommodate their treatment needs, which will vary according to a number of factors, including the individual’s age, the severity of their condition, and any other medical conditions they may have.

Symptoms of ulcerative colitis

A person who is affected by ulcerative colitis may experience a wide range of possible symptoms, to varying degrees of severity, including:

Intestinal symptoms

Symptoms which are directly related to one’s intestinal health, such as:

Extraintestinal manifestations

Symptoms related to a person’s overall level of health and/or symptoms which affect other areas of the body. Possible extraintestinal manifestations of UC may include:

  • Involuntary weight loss
  • Loss of appetite
  • Fatigue
  • Malnutrition
  • Inflammation affecting the eyes, skin or joints

If you think you or a loved one may be showing signs of ulcerative colitis, or are otherwise unwell, you can get a free symptom assessment at any time by downloading the Ada app.

Subtypes of ulcerative colitis

UC almost always begins in the rectum and spreads upwards through the bowel in a continuous fashion. The scope of symptoms depends on what section of the colon the inflammation reaches. For this reason UC can be divided into the following subtypes: 2


This type of UC only affects the rectum. This is the mildest type of UC, as the colon itself is generally able to function as normal. Symptoms are usually directly related to defecation, including diarrhea, tenesmus (a sensation of urgency without defecation) or, in some cases, constipation. Most people with proctitis will pass blood or blood stained mucus from the rectum.


Inflammation occurs in the rectum as well as the sigmoid colon - the final section of the colon which adjoins the rectum. The symptoms are similar to those of proctitis, although constipation is much less likely. Further health complications are significantly less likely to develop from proctosigmoiditis, compared to cases where a greater intestinal area is affected. 3

Distal colitis

Also known as left-sided colitis, distal colitis affects the the left side of the colon, the sigmoid colon and the rectum. This is the most common form of UC, and recent treatment approaches have focused on devising medications that target the distal portion of the colorectal area. 4 Distal colitis can cause pain on the left side of the abdomen, as well as the symptoms listed above.


Also known as total colitis or universal colitis, pancolitis affects the entire colorectal area. Symptoms may include severe abdominal pain and cramping, as well as frequent episodes of diarrhea, often accompanied by blood, mucus and pus. Fever, weight loss and other systemic health complications may also be present, as pancolitis can impact the colon’s ability to take in nutrients, compromising a person’s overall health. 5

Extensive colitis

This is a form of UC in which the majority of the colon is affected, but not the entire colon; the part of the colon directly adjoining the small intestine is not affected. The symptoms, treatment and outlook for extensive colitis are almost identical to those of pancolitis.

Fulminant colitis (rare)

UC can also be classified according to its severity, with fulminant colitis being one of the rarest and most severe forms. Fulminant colitis usually affects people who have already been diagnosed with another, less severe form of UC. 6 Symptoms include severe pain and cramping, intense and protracted episodes of diarrhea, and bleeding.

Immediate medical attention is needed if fulminant colitis occurs, as life-threatening complications like toxic megacolon can occur if it is left untreated. 7

Symptoms: flare-ups

Not everybody will experience all of the possible symptoms of UC. People with ulcerative colitis often find their symptoms vary over time, and that they experience periods of:

  • Flare-ups, in which the inflammation is active, new damage occurs to the intestinal tissue and the individual experiences additional symptoms or a worsening of symptoms.
  • Remission, in which the inflammation is inactive, their intestinal tissue can begin to heal and symptoms may be absent or mild enough not to interfere with day-to-day routine.

Flare ups can occur despite treatment for UC. The symptoms of a flare-up vary between people, depending on factors like the type and severity of UC, as well as how a person defines a period of remission.

Frequent or prolonged flare-ups of UC may increase one’s likelihood of developing related health complications. People who are in remission are usually advised to contact their healthcare professional if they suspect the beginnings of a flare-up, so that a specific treatment plan can be devised.

In severe flare ups the following additional symptoms may occur:

  • Shortness of breath
  • Fast or irregular heartbeat
  • High temperature

These symptoms require immediate medical assessment.

Causes of ulcerative colitis

UC is understood to result from an inappropriate immune response, although the exact cause for this response is not fully understood, and is likely to vary between individuals. Factors which may be involved include:

  • Genetic predisposition. Ulcerative colitis is more common in people with an affected parent or sibling.
  • Environmental triggers. Factors such as adverse reactions to one’s diet and/or medications, stress, and living in deprived socioeconomic circumstances are found to precipitate UC.
  • Infections. Bacterial infections – such as Salmonella and Shigella – may trigger an abnormal immune response in certain genetically-predisposed individuals, causing the immune system to inappropriately attack the lining of the digestive tract.

Risk factors

People of any age can be affected by UC, but it usually first manifests in adulthood, with peaks in young adulthood between the ages of 15 and 30, and in older adults between the ages of 50 and 70. 8 Risk factors for developing UC include: 9

  • Being of Caucasian descent; some studies conclude that Ashkenazi Jewish people are particularly at risk
  • Having immediate family members with the condition
  • Living in an industrialized country in an urban area with a high concentration of people 10

Although some kinds of infectious bacteria can sometimes bring about a flare-up of UC, UC itself is not an infectious condition. It cannot be passed from one person to another via bodily contact.

Additional risk factors include: 11

Not having had an appendectomy (an operation to remove one’s appendix). UC diagnosis has been found to be slightly less common in people who have previously had their appendix removed due to abdominal inflammation, but appendectomy will not cure UC which is already present. Furthermore, it is not considered to be a preventative measure, because the relationship between the procedure and the condition is not yet sufficiently understood.

Not using tobacco products. Nicotine, a component of tobacco, is believed to have immunosuppressive effects, which seem to reduce one’s likelihood of experiencing the autoimmune overreaction that precipitates UC.

However,using tobacco products is not considered to be a relevant preventative measure against UC and is never medically advisable. This is due to the many other health complications which may be precipitated or worsened by smoking, including Crohn’s disease, the other main form of IBD.


For many people, the presence of blood or pus in their stools is an important warning sign of possible UC. It is advisable to seek medical attention promptly if this occurs, to enable early diagnosis if UC is present, and to begin treatment before symptoms worsen or increase in number.

When UC is suspected, the doctor will consider a person’s medical history, including previous episodes of digestive discomfort, their lifestyle, including dietary and environmental factors, and whether they have family members affected by UC.

The initial consultation will also include a physical examination. The doctor will look out for indications of health complications associated with UC, such as malnutrition (as a result of malabsorption), pale complexion (anemia), abdominal tenderness and red, itchy eyes (uveitis).

To make a definitive diagnosis of UC, it is important that the doctor rules out other possible causes for the presenting symptoms. Other conditions that can be associated with rectal bleeding or diarrhea include: 12

  • Crohn’s disease, the other main form of inflammatory bowel disease (IBD)
  • Other forms of colitis such as ischemic colitis (caused by a loss of blood supply to part of the colon) and infectious colitis (when bacteria cause irritation in the colon)
  • Lactose intolerance (which occurs when a person cannot digest foods containing lactose, which can cause irritation in the colon)
  • Hemorrhoids (swollen veins in the rectum)
  • Irritable bowel syndrome (IBS)
  • Colorectal cancer

Diagnostic tests will normally be scheduled in order to rule out other possible causes of a person’s symptoms, to confirm a diagnosis of UC if present, and to establish the type and severity of the condition.

Diagnostic tests for UC include:

Stool sample

This is carried out to screen for the presence of bacteria, which can help rule out other infectious causes for one’s symptoms, such as gastroenteritis.

Blood tests

A doctor will usually perform some standard blood tests, as well as some more specialized blood tests, called antibody tests or biomarkers. Standard tests including a person’s complete blood count (CBC) to detect anemia and/or infection, as well as liver function, electrolyte and mineral levels, as these may also be affected by diarrhoea and malabsorption.

Antibody blood tests are sometimes useful to differentiate between UC and Crohn’s disease. These examine proteins called antibodies produced by the immune system, which can indicate the presence of particular diseases.

Read more about Blood Test Results »


Imaging techniques may include: 13

  • X-ray. In addition to CT or MRI scanning, a regular X-ray may be taken initially, to look for signs of inflammation/thickening in the bowel wall.
  • Computed tomography (CT) scanning. An abdominal CT scan is the primary type of imaging used to investigate IBD.
  • Magnetic resonance imaging (MRI) scanning. Ideal for people who may wish to avoid the ionizing radiation associated with CT scanning and traditional X-rays, for example pregnant women and those undergoing other treatments involving radiation, such as radiation therapy for cancer.

Endoscopy and biopsy

An endoscopy is a procedure which usually involves inserting a thin, flexible tube called an endoscope into the body to examine an area of the gastrointestinal tract. A biopsy (tissue sample taken from the affected area for laboratory analysis) may be taken simultaneously. The specific types of endoscopy which may be used in the diagnosis of UC are: 14 15

  • Sigmoidoscopy. To examine the rectum and final portion of the colon, using a short endoscope, in suspected cases of proctitis or proctosigmoiditis.
  • Colonoscopy. To examine the entire length of the colon, in suspected cases of distal colitis or pancolitis.
  • Colon capsule endoscopy (CCE). A new technique which may sometimes be used in the diagnosis of inflammatory bowel disease, which involves swallowing a small capsule containing a camera which passes through the entire gastrointestinal tract. Its detection of inflammation is not considered to be as extensive as traditional techniques, and it is not possible to take a biopsy using CCE.

Read more about Preparing for a Colonoscopy »

Treatment and management

Ulcerative colitis is a lifelong (chronic) condition, and treatment focuses on alleviating symptoms during flare-ups and bringing about or prolonging periods of remission. Although there is no cure for UC, with appropriate treatment and management it is often possible for a person with UC to experience periods of remission lasting years or decades, and to live a fulfilled, active life. During remission, a person’s symptoms will usually be absent, or mild and easily managed. Treatments for UC may include:

Aminosalicylates (5-ASAs)

Aminosalicylates (also called 5-ASAs) are anti-inflammatory medications which are prescribed as a first-line treatment for UC. They are suitable in cases of mild or moderate UC, and can be taken in the long-term, to maintain remission, or short-term, to calm flare-ups. The dose and method of administration depends on the severity of one’s UC.

Corticosteroid medications

Corticosteroid medications are a more powerful type of anti-inflammatory medication than aminosalicylates and may be used to treat flare-ups in cases where aminosalicylates have not calmed the symptoms on their own. Corticosteroids are suitable for short-term use and are a commonly prescribed treatment for flare-ups. Long-term use of corticosteroids is associated with problematic side effects including osteoporosis, weight gain and the development of other gastrointestinal disorders.

Immunosuppressant medications

These medications work by reducing the activity of one’s immune system. In this way, they can serve to alleviate the intestinal inflammation that occurs in people with IBD. They are used to treat mild or moderate flare-ups (often to be administered intravenously under hospital supervision), and to maintain remission in people whose symptoms do not respond to other medications.

Biologic medications

Biologic therapies are usually prescribed in cases where other treatments have not worked, rather than as a first-line treatment. They are a type of immunosuppressant medication which use naturally occurring substances such as antibodies and enzymes to inhibit the effects of UC. 16

The most commonly prescribed biologic medications used to treat UC are Infliximab and Adalimumab. These are suitable for both adults and children with moderate to severe UC. They are also called anti-TNF medications because they inhibit a protein called the TNF-alpha, which is found in everybody’s blood as a response to infection. 17


In cases where medications have not alleviated the symptoms of UC or in cases where a person’s quality of life is severely compromised by their condition, surgery to permanently remove the entire colon may be recommended, with a procedure called a total colectomy. It is carried out as an inpatient procedure under general anesthetic by a colorectal surgeon. This may be performed using open surgery or laparoscopic (minimally invasive) surgery.

The removal of the colon necessitates the installation of an alternative mechanism for waste to leave the body. This may involve:

An ileostomy

The small intestine will be redirected so that its contents exit the body through a hole made in the abdomen called a stoma. One can attach a colostomy bag to the hole to collect bodily waste. Ileostomies can either be temporary (in which case, an ileo-anal pouch will eventually be created during a subsequent operation), or permanent.

An ileo-anal pouch

Also known as a J-pouch, this involves creating a pouch inside the body from the tissue of the small intestine. The pouch is connected to the anus and replaces the colon, allowing waste to pass though as normal.

Both the colectomy itself and one’s life afterwards present challenges for an individual to adapt to. Some people may therefore prefer to manage their UC with non-surgical treatments.

Living with UC

People living with UC may find it helpful to: 18

  • Establish a good relationship with their medical care team
  • Let their loved ones and colleagues know as much as necessary about their condition so as to prepare for times when they are incapacitated or unavailable due to a flare-up
  • Receive counseling or therapy to treat any anxiety and stress engendered by UC
  • Ensure access to sufficient supplies of medications at all times
  • Find out the location of nearby restrooms in all locations they will visit during the course of a day


There is no recommended diet for people with UC. However, individuals may find that certain foods trigger the symptoms of UC.

Many people with UC find it helpful to:

  • Avoid substances which induce bowel movements, such as spices, caffeine, alcohol and laxative fruits
  • Experiment with low-residue foods, such as cooked, peeled vegetables, white bread and lean meat (this can reduce the size and frequency of one’s stools)
  • Drink plenty of fluids to avoid the dehydration which is often caused by diarrhoea
  • Keep a food diary to record items which may have precipitated an adverse digestive reaction
  • Take food supplements such as vitamins and minerals to replace those lost due to diarrhea and/or malabsorption
  • Eat multiple small meals per day, as opposed to a few large ones, in order to avoid putting too much pressure on the gastrointestinal system

It is advisable to discuss one’s diet with the doctor during the initial consultation about UC and again before making significant changes to it. The doctor will be able to advise on the most sensible diet plan for an individual’s profile and condition, taking their treatment plan into account.

Complications of ulcerative colitis

In addition to experiencing the symptoms of ulcerative colitis, people with UC are predisposed to develop a number of further health complications. However, by diagnosing and beginning to treat UC promptly one can decrease the likelihood of developing any complications. Possible complications of UC include: 1 19 20 21 22 23

  • Fistula. An abnormal passage between the bowel and surrounding structures.
  • Gastrointestinal perforation. A life-threatening complication, in which a hole develops in the wall of the gastrointestinal tract. The earliest symptom of this is usually severe pain which worsens with movement. .
  • Stricture. The narrowing of part of the colon or rectum. Surgery may be needed to remove the affected part of the colon.
  • Toxic megacolon. A rare complication in which the colon expands and dilates, often due to bacterial infection. This can result in the rupturing of the colon.
  • Colorectal cancer (CC). People with UC are at higher risk of contracting CC. It is recommended that they undergo regular screening.
  • Osteoporosis. A skeletal disorder in which the structure of the bones becomes porous.
  • Arthritis. Inflammation and stiffening of the joints. This often co-occurs with flare-ups.
  • Anemia. A deficiency of healthy red blood cells, which can result in pale skin and fatigue.
  • Skin disorders. Several dermatological problems are linked to UC. They tend to worsen during a flare-up and improve when the UC is brought under control.
  • Eye problems. People with UC are at increased risk of eye problems, including uveitis.
  • Primary sclerosing cholangitis (liver disease). A uncommon, chronic form of liver disease, often discovered in routine blood tests.

Read more about Osteoporosis »

Read more about Anemia »

Read more about Uveitis »

Ulcerative colitis FAQs

Q: What are the differences between ulcerative colitis and Crohn’s disease?
A: Ulcerative colitis shares several important characteristics with Crohn’s disease. They are both forms of inflammatory bowel disease (IBD) and are chronic (long-term) conditions which involve inflammation of the gut. However, ulcerative colitis only affects the large intestine, whereas Crohn’s disease can affect any part of the gastrointestinal system.

The two conditions may differ in their symptoms. People with Crohn’s disease tend to produce bulky stools containing undigested fats, whereas stool samples from people with ulcerative colitis are more likely to contain blood. Tenesmus and rectal pain are more characteristic of ulcerative colitis, whereas fistulae and weight loss are more likely to occur in cases of Crohn’s disease. 24 If you think that you or a loved one may be experiencing symptoms of either of these conditions, you can get a free symptom assessment by downloading the Ada app.

Q: Will ulcerative colitis affect one’s pregnancy?
A: It is possible for people with UC to have an uncomplicated conception and pregnancy and a healthy baby. However, doctors recommend conceiving at a time when neither partner is experiencing a flare-up of UC. 25 Problems associated with conception during a flare-up of UC may include:

  • An increased likelihood of having active UC during pregnancy, in comparison to women who become pregnant during a period of remission
  • In turn, in those affected by flare-ups of UC during pregnancy, there are heightened risks of pregnancy complications such as preterm birth or low birth weight, and adverse pregnancy outcomes such as miscarriage

However, it is possible to conceive during a flare-up and/or experience a flare-up during pregnancy and still give birth to a healthy baby. 25 Many medications for UC can be safely taken during pregnancy and whilst breastfeeding. A specialist doctor will advise on appropriate management of UC during pregnancy.