Rectal bleeding can be a symptom of ulcerative colitis (UC). Severe bleeding that causes individuals to experience fainting, dizziness, or intense pain can be serious.

People may experience blood in their stools or slow and steady bleeding without bowel movements. A person experiencing severe bleeding needs to seek emergency medical care.

This article explores how UC affects the appearance of stools, when to contact a doctor about bleeding, and treatment options.

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Severe bleeding that causes people to experience any of the following requires emergency medical attention:

Individuals will also need emergency care if they vomit blood.

While severe bleeding, called hemorrhaging, is uncommon in UC, it can become life threatening if it occurs. People experiencing this need to call 911 or go to the emergency room immediately.

If a person has no severe symptoms but is unsure if they have excessive bleeding, they can contact their doctor to discuss their symptoms.

Rectal bleeding is a common symptom of UC.

This is because the condition causes small ulcerations in the lining of the large intestine, leading to blood appearing in the stools. Ulcers in the lining of the rectum can also cause bloody stools.

Additionally, although uncommon, perianal disease may develop in people with UC. This can cause anal fissures and hemorrhoids, which may lead to blood appearing in stools.

People may have varying levels of rectal bleeding, but not everyone experiences this symptom in large amounts.

Bleeding during flares

Certain factors can cause flare-ups of UC, which are periods where symptoms worsen, including rectal bleeding.

These factors can include:

According to the Canadian Institute of Intestinal Research, most people with UC experience varying levels of rectal bleeding. The blood is usually clearly visible in the stool or on the surface.

Blood from the rectum and large intestine is usually bright red. If blood is a darker color, it may be coming from higher up the gastrointestinal tract.

People with UC may have slow, steady bleeding when they do not have a bowel movement. They may also experience bloody diarrhea.

Some individuals with severe UC may notice blood in their stools more than 10 times a day.

According to the Crohn’s and Colitis Foundation, people need immediate medical attention if they experience rectal bleeding with blood clots in stools.

Learn more about how UC can affect stools.

People need to discuss any blood in the stools with their doctor, even if they have experienced it before.

A person may also wish to monitor their UC symptoms so they know what is usual for them. They can then discuss any atypical symptoms with a healthcare professional.

If individuals have ongoing diarrhea that lasts a few weeks, it is best they contact a doctor for advice.

The Crohn’s and Colitis Foundation advises people to seek emergency medical attention if they experience any of the following:

Numerous treatments may help stop or treat bleeding associated with UC.


Managing UC with treatment may help reduce bleeding.

Medications that reduce inflammation in the rectum and large intestines may also reduce bleeding.

Anti-inflammatory medications for UC can include:

  • 5-aminosalicylic acid: This is a type of medication that may help reduce acute inflammation and cause inflammation to become inactive over time.
  • Corticosteroids: These are short-term treatments to help reduce inflammation.
  • Immunosuppressants: These medications can help suppress the immune response, which can be a cause of inflammation. However, they may take up to 6 months to be effective.
  • Biologics: For treatment of moderate to severe UC, biologics help block molecules that trigger inflammation.

It may be best for people who are taking pain medication to manage symptoms to take acetaminophen instead of NSAIDs, which can irritate the bowels.

In some cases, if individuals experience frequent blood loss, they may develop anemia. A doctor may recommend supplementing with iron, folic acid, or vitamin B12 to help manage anemia.


A person may also find that certain foods trigger UC flare-ups.

Trigger foods can vary between individuals, and people may find it helpful to talk with their doctor or a dietician to develop a diet plan. Eating smaller meals more frequently may also help.

Rectal bleeding can cause a loss of bodily fluids, nutrients, and electrolytes, especially if people are also experiencing diarrhea. A well-balanced, nutritional diet can help prevent nutritional deficiencies.

Learn more about foods to eat and avoid with UC.

Other procedures

If people have severe blood loss or hemorrhaging, they may need a blood transfusion to replace the lost blood.

When other therapies are ineffective in treating colonic inflammation, a person may need surgical treatment. This may involve the surgical removal of a part of the colon, the entire colon, or the entire colon and rectum.

If a doctor removes the entire colon and rectum, they can repurpose one end of the small intestine to function as a pouch, which healthcare professionals call a J-pouch. This attaches to the anus and allows waste to pass out of the body.

Learn about J-pouch surgery for UC.

Below are answers to some common questions about UC.

How long does ulcerative colitis bleeding last?

How long ulcerative colitis (UC) bleeding lasts will differ for each person. Some bleeding may persist for the duration of the UC flare, with a person passing as many as 10 bloody stools in a day.

It is important to contact a doctor if a person notices any blood in their stool. They may wish to keep a record of how frequently they see blood, as this can help them detect any changes in frequency.

What is the fastest way to calm ulcerative colitis symptoms?

A doctor will typically recommend medication to help manage UC symptoms.

Some medications, such as corticosteroids, offer quick but short-term relief. Others, such as immunosuppressants, can take months to start working effectively and are better for long-term management.

What is the permanent solution for ulcerative colitis?

Although there is no cure for UC, various medications can help a person manage the condition. In some cases, a doctor may also recommend surgery.

How do you end an ulcerative colitis flare-up?

If a person is experiencing a UC flare-up, avoiding triggers that worsen their symptoms may help. This can include avoiding any known trigger foods. Taking medication that a doctor has prescribed can also help.

Rectal bleeding is a common symptom of ulcerative colitis. Inflammation and ulcers in the rectum and colon can cause blood to appear in the stools. People may also experience slow, steady bleeding without any bowel movements.

People should discuss any rectal bleeding with their doctor, even if they have experienced bleeding before. They can also inform their doctor about any other changes in stools, such as persistent diarrhea or constipation.

A doctor may advise changing medication or other treatment methods and making dietary and lifestyle changes that could help.

Individuals need to seek emergency medical attention if they have severe bleeding, blood in their vomit, or any bleeding that causes them to experience dizziness, faintness, chest pain, shortness of breath, or severe pain.