Rectal bleeding can be a symptom of ulcerative colitis. Severe bleeding, or bleeding that causes individuals to feel faint, dizzy, or intense pain, can be serious.

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

If people do not experience these symptoms but still have concerns about the amount of blood they notice in their stools, they should still contact a doctor.

This article explores how ulcerative colitis (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 feel faint, dizzy, or in severe pain could be a sign of passing too much blood. In these cases, a person needs to seek emergency medical attention. Individuals will also need emergency care if they are vomiting blood.

While severe bleeding, or hemorrhaging, is uncommon in UC, it can become life threatening. People 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 healthcare provider to discuss their symptoms.

Learn more about hemorrhaging here.

Rectal bleeding is a common symptom of UC. The condition causes small ulcerations in the lining of the large intestine, which then leads to blood appearing in the stools.

Ulcers in the lining of the rectum and large intestine can also cause bloody stools. Anal fissures, or hemorrhoids, are a common complication of UC and other types of inflammatory bowel disease, which may also cause blood in stools.

People may have varying levels of rectal bleeding, but not everyone experiences this symptom in large amounts. Certain factors can cause flare-ups of UC and might worsen symptoms, including rectal bleeding. These factors can include:

Learn more about UC flares here.

According to the Canadian Institute of Intestinal Research, most people with UC experience varying levels of hematochezia, which refers to blood in the stools. The blood will usually be clearly visible in the stool — which has a semi-solid consistency — or on the surface. The blood color can range from bright red to maroon, with or without blood clots. This symptom often accompanies lower abdominal pain and the urgent need to defecate.

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 and constipation.

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

People with UC will also usually have mucus in the stools but may not be able to see it. The mucus helps protect the inner lining of the intestines, as well as helping with bowel movements.

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 blood clots in the stools here.

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 to experience. People can then discuss any abnormal symptoms with a healthcare professional.

If individuals have ongoing diarrhea that lasts for a couple of weeks, they can contact their doctor to discuss concerns and treatment.

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

  • inability to keep down liquids due to nausea, vomiting, or pain
  • rectal bleeding with blood clots in stools
  • continuous pain
  • high fever above 100.3°F (38°C)
  • rapid heart rate above 100 beats per minute
  • rapid weight loss
  • severe abdominal or rectal cramps

Managing UC with treatment may help reduce bleeding. There are medications that may reduce inflammation in the rectum and large intestines, which may, in turn, reduce bleeding.

Anti-inflammatory medications for UC can include:

  • 5-Aminosalicylic acid: Medication that may help reduce acute inflammation and causes inflammation to become inactive over time.
  • Corticosteroids: A short-term treatment to help reduce inflammation.
  • Immunosuppressants: These medications can help suppress the immune response that can cause 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.

If people are taking pain medication to manage symptoms, it may be best 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.

Learn more about medications for UC here.


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.

A person may also find that certain foods trigger UC flare-ups. Trigger foods can vary between each individual, and people may find it helpful to talk to their doctor or a dietician to develop a diet plan. Eating smaller meals more frequently may also help. In addition, following a high fiber diet can promote healthy bowel movements and reduce hemorrhoidal injuries that may develop with UC.

Other procedures

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

If other therapies are not effective 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 refer to as a “J-pouch.” This attaches to the rectum and allows waste to pass out of the body.

Learn about J-pouch surgery for UC here.

Rectal bleeding can be a common symptom of UC. Inflammation and ulcers in the rectum and large intestines can cause blood to appear in the stools. People may also experience slow, steady bleeding without any bowel movements.

A person needs to discuss any rectal bleeding with their healthcare provider, even if they have experienced bleeding before. People can also let their doctor know about any other changes in stools, such as persistent diarrhea or constipation.

A doctor may advise a change in medication or other treatment methods, as well as any 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 feel faint, dizzy, or intense pain.