Ulcerative colitis (UC) is a long-term condition causing inflammation of the bowel, including the colon and rectum. Doctors measure the condition by how far along the colon it progresses. This can lead to complications and other types of colitis, including proctitis, left sided UC, and toxic colitis.

Infographic demonstrating the different areas of the intestine affected in types of UCShare on Pinterest
Infographic by Jason Hoffman

UC is a form of inflammatory bowel disease (IBD).

Doctors categorize UC according to how much of the large intestine it has affected. Inflammation and ulceration of the inner lining of the colon and rectum can cause redness, swelling, and pain. This may also extend to the whole of the colon.

Currently, there is no cure for UC, but it is possible to manage symptoms with medications, lifestyle changes, and, in severe cases, surgery.

This article provides an overview of UC and its types, including causes, symptoms, diagnosis, and treatment.

In 2015, around 3 million adults in the United States had a type of IBD.

The colon is part of the digestive system. Its role is to absorb water and form stool, which a person evacuates out the body through the rectum and anus. UC can disrupt this process, as it causes ulcers to form in the lining of the colon. This may result in:

The way a person’s immune system reacts to UC depends on the individual. Some people may have mild symptoms, such as mild cramping and loose stools, that occur occasionally, while others may experience more intense pain and frequent, sometimes watery stools.

Other individuals may have chronic symptoms that can affect their quality of life and require medical treatment, including surgery.

Experts do not exactly know what causes UC. Factors that may play a role in the development of the condition include:

A person may develop different types of UC. The condition can be mild, moderate, or severe, depending on the areas affected.

The extent of the inflammation and the severity of the condition help guide the management and treatment of UC.

All types of UC may require the following medical interventions throughout the course of the condition:


In order to make a diagnosis of any type of UC, a doctor may perform the following:

  • blood tests
  • stool tests
  • barium enema, which involves a healthcare professional passing barium fluid through a person’s colon to show any anomalies in a scan
  • sigmoidoscopy, during which a doctor inserts a flexible tube with a camera through the anus to examine a person’s rectum
  • colonoscopy, which involves a doctor examining the whole colon using an endoscope
  • a CT scan of the abdomen or pelvis


Some common treatment methods that all types of UC may require include:


UC increases the risk of developing colon cancer, especially if symptoms are severe or extensive.

A doctor may recommend a regular colonoscopy or blood tests to assess the presence of the active condition and reduce any risk of complications.

In the sections below, we describe the different types of UC and accompanying symptoms. There may be some overlap between the conditions, as they tend to occur in similar areas of the colon.

Proctitis is the development of inflammation limited to the rectum. It can be short-term, or acute, but it can also be long lasting or chronic.

One possible cause of proctitis is UC, but it may also result from:

Proctitis may develop farther in the colon and lead to other forms of UC, including left sided UC or pancolitis.


Common symptoms of proctitis include:

  • an urgent need to have a bowel movement
  • constipation or diarrhea
  • cramping or pain in the rectum, in the anus, or to the left of the abdomen while having a bowel movement
  • bleeding from the rectum or blood in stool
  • stools with mucus or pus

If a person has pain in the abdomen or passes pus, mucus, or blood while having a bowel movement, they should seek immediate medical attention.


First-line treatment will likely involve drugs to help reduce inflammation.

Doctors will also prescribe 5-aminosalicylic acid (5-ASA), also called mesalamine, via enema once or twice per day, depending on the severity of the condition.

Other drugs doctors use to treat proctitis may be similar to the ones that treat other types of UC, such as corticosteroids and biologics.

If the drugs do not relieve symptoms, a doctor may offer surgery to remove part of the affected area of the colon.

Inflammation of left sided, or distal, UC starts from the rectum and continues into the colon as far as the bend in the colon by the spleen. The condition affects the rectum and the lower part of the colon that attaches to the rectum.


Symptoms can include:


Treatment for left sided UC is similar to that for other types of UC and includes individual or a combination of IBD medications.

People with left sided inflammation may also receive 5-ASA drugs in oral form or enemas.

Proctosigmoiditis is similar to left sided UC, but it does not affect the colon as extensively. The condition only affects the rectum and lower part of the colon — the sigmoid colon.


The condition manifests similarly to left sided UC, causing, among others:

  • loss of appetite
  • unexplained weight loss
  • bloody diarrhea


Individuals with mild to moderate ulcerative proctosigmoiditis will receive mesalamine treatment, which is similar to the treatment for mild proctitis.

A person can also adjust their diet and try to avoid foods that may result in a UC flare or return of symptoms.

Doctors may prescribe medical treatments similar to those for other types of UC. However, individuals can also take other medications to manage symptoms, such as antidiarrheal medication. This may help with abdominal cramps as well.

A doctor may provide a person with alternative treatments or diets that will not trigger proctosigmoiditis or other types of UC.

Pancolitis, or extensive colitis, is an advanced form of UC that has spread through the entire colon. People with pancolitis have a higher risk of developing colon cancer than individuals without UC.


Symptoms of pancolitis are similar to those of other forms of colitis, including:

  • diarrhea with blood
  • pain in the abdomen
  • an urgent need to empty bowels
  • unexplained weight loss
  • fever


Treatment for pancolitis is similar to those for other forms of UC and includes:

  • medications
  • lifestyle and dietary changes
  • surgery, where necessary

Toxic colitis, which doctors sometimes also call fulminant colitis, is a complication of severe UC. It may result in perforation of the bowel, sepsis, and possibly death.


Symptoms include more than six bloody stools per day. There will also be signs of toxicity, such as:

Learn more about this severe case of UC here.


Important components of a treatment plan for toxic colitis include:

  • treating the underlying cause
  • addressing any electrolyte imbalances, such as hypokalemia
  • managing symptoms
  • preventing further complications

A healthcare professional may admit a person to an intensive care unit in case of an unexpected worsening of symptoms. Doctors will start by checking the person’s complete blood count and electrolyte levels every 12 hours.

The person will need to stop taking any medication that may irritate the colon, such as opioids and anticholinergics. However, they will receive IV fluids to provide adequate hydration. IV administration involves delivering medication or other fluids directly into a person’s bloodstream with the use of a thin tube or catheter inserted into a vein.

Due to a high risk of perforation, doctors frequently prescribe antibiotics.

Also, the person will need to be on bowel rest. This means they will not have any food or drink by mouth so that the digestive tract can rest. As symptoms continue to improve, they can gradually start drinking and eating by mouth to promote gut healing.

If this treatment does not improve the condition, a surgical procedure, such as a colectomy, may be necessary.

Colitis and Crohn’s disease are both inflammatory bowel conditions. They have some similarities and differences.

The main similarities are the following:

  • Both conditions usually result in inflammation of parts of the digestive tract.
  • There is no known cause of either, but it may include the microbiome, environmental factors, and genetics.
  • Both conditions disrupt food digestion, nutrition absorption, and waste elimination.
  • There is no cure for either of the conditions. However, people may be able to relieve symptoms with diet and medications.
  • Both conditions may increase the risk of colon cancer, lymphoma, and skin cancer due to treatment.

Colitis mainly affects the large intestine or colon and usually starts at the rectum. By contrast, Crohn’s disease can occur at any place in the digestive system and usually develops in the lower small bowel and upper colon.

Learn more about the differences between Crohn’s disease and colitis here.

A person should visit a healthcare professional if they develop symptoms suggestive of colitis, including:

  • blood in stool
  • abdominal pain and cramping
  • urgent and frequent need to have a bowel movement

During the visit, a healthcare professional may do the following:

  • check a person’s medical history and medication
  • ask about their lifestyle, including smoking
  • carry out a physical examination
  • order some tests to rule out infection

Outlook for people with colitis will depend on how severe their initial condition is and how much of the bowel it has affected.

People can manage mild cases, which involve just the rectum or a small portion of the colon, and flare-ups at home. A person can get symptoms under control with medication or lifestyle changes, which may lead to remission or a period with no symptoms.

A 2019 study notes that colitis may develop farther along the colon the longer a person lives with the condition. This may lead to more frequent flare-ups and require more medication.

UC can develop as a mild, moderate, or severe condition. It affects the body’s ability to process food and eliminate waste.

The different ways UC affects the colon will determine what type of condition a person has. Doctors will diagnose the type of UC based on the location of the inflammation.

In most cases, individuals can manage their condition with diet, medication, and regular checkups. In severe cases, a person may require surgery.