Bloody Diarrhea: Causes

By McBratney, Susan PhD
By Spader, Catherine RN

What causes bloody diarrhea?

Bloody diarrhea can indicate a relatively mild condition, such as a hemorrhoid or anal fissure, or it can be caused by a life-threatening condition, such as ruptured esophageal varices or bleeding peptic ulcer.

In children, bloody diarrhea is most commonly due to a bacterial infection and inflammation in the lower gastrointestinal system. This is often linked to eating food contaminated with bacteria and parasites.

Black, tarry diarrhea usually indicates that the blood is coming from the upper gastrointestinal tract (esophagus, stomach and duodenum), while bright red or maroon-colored diarrhea often originates from bleeding in the lower gastrointestinal tract (colon, rectum and anus). Bloody diarrhea that is associated with dizziness or vomiting blood should be immediately evaluated in an emergency setting.

Gastrointestinal tract causes of bloody diarrhea

Causes of bloody diarrhea related to the gastrointestinal tract include:

  • Anal fissure

  • Bleeding peptic ulcer

  • Blood vessel malformation

  • Bowel ischemia or bowel obstruction

  • Colon cancer

  • Constipation

  • Diverticulosis

  • Esophageal trauma or esophageal varices

  • Gastroenteritis

  • Hemorrhoid

  • Inflammatory bowel disease (Crohn’s disease or ulcerative colitis)

  • Intestinal infection (food poisoning)

  • Intestinal polyps or intestinal tumor

  • Meckel’s diverticulum (an abnormal pouch near the lower end of the small intestine)

  • Rectal prolapse

  • Stomach varices

Other causes of bloody diarrhea

Bloody diarrhea can also be caused by:

  • Medication side effects

  • Radiation therapy

Serious or life-threatening causes of bloody diarrhea

Any type of bloody stools should be evaluated by a health care professional. Bloody diarrhea can indicate a serious and potentially life-threatening disease, disorder or condition including:

What are the potential complications of bloody diarrhea?

Over time, bloody diarrhea can lead to serious complications including:

  • Anemia

  • Dehydration

  • Hemolytic uremic syndrome or other type of kidney failure

  • Severe blood loss

  • Shock


  1. Bloody or tarry stools. Medline Plus, a service of the National Library of Medicine National Institutes.
  2. Dysentery. World Health Organization.
  3. Gastrointestinal Bleeding. Medline Plus, a service of the National Library of Medicine National Institutes of Health.
  4. Lower Gastrointestinal Bleeding. Medscape.

What is bloody diarrhea?

Bloody diarrhea is a potentially critical condition in which there is blood mixed in with loose, watery stools. The blood can arise from anywhere along your digestive tract, from the mouth to the anus. Bloody diarrhea is often a sign of gastrointestinal bleeding due to injury or disease. Diarrhea that contains bright red or maroon-colored blood may be referred to as hematochezia, while melena i... Read more about bloody diarrheaintroduction


What other symptoms might occur with bloody diarrhea?

Depending on the underlying disease, disorder or condition, bloody diarrhea may occur with other symptoms including:

Medical Reviewer: Cynthia Haines, MD Last Annual Review Date: Jul 31, 2013 Copyright: © Copyright 2014 Health Grades, Inc. All rights reserved. May not be reproduced or reprinted without permission from Health Grades, Inc. Use of this information is governed by the HealthGrades User Agreement.

This Article is Filed Under: Digestive System, Ulcerative Colitis

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