Possible Causes of Bloody Stool

In medicine, at face value, a single symptom like bloody stool can usually be attributable to several conditions. Blood in the stool typically presents as blood-red or maroonish and represents a bleed somewhere in the gastrointestinal (GI) tract from mouth to anus.

If blood is coming from the upper GI tract and is being digested, it can also take on a black, tar-like appearance called melena.

Using details from your history, physical exam, diagnostic tests and so forth, physicians are able to deduce the etiology or cause of symptoms and rule out various differential diagnoses. In the spirit of differential diagnoses, here are 10 possible causes of bloody stool. (Please note that this list omits infectious causes like E. coli.)

potential causes of bloody stool

Verywell / Laura Porter

Upper GI Bleed

As any surgeon can attest to, the most common cause of a lower GI bleed is an upper GI bleed. When you bleed copiously from an anatomical structure proximal to the ligament of Treitz, a ligament that suspends the distal duodenum, the blood can appear undigested in your stool (rapid transit).

In order to figure out whether you have an upper GI bleed, a gastroenterologist will perform an endoscopy. Following resuscitation measures like airway stabilization or blood transfusion, patients with serious upper GI bleeds need surgery.

Anal Fissure

Although anal fissures also happen in adults, these fissures are the most common cause of bloody stool in infants. Such fissures are caused by constipation or passing of a large, firm stool. Anal fissures are cracks in the skin that are visualized after stretching the skin of the anus.

Fortunately, anal fissures usually heal on their own. Stool softening measures and application of petroleum jelly or some other cream can help with pain and discomfort.


The nonspecific term polyp refers to any projection from the intestinal tract. There are several types of polyps which vary depending on their histology and presentation. Adenomatous polyps are pretty common—affecting about 25% of adults aged 50 and older.

Most cases of colorectal cancer evolve from adenomatous polyps. Colorectal cancer is the third leading cause of cancer-related deaths in the United States.

However, with advances in medicine, non-metastatic adenomatous polyps can be resected or removed by surgery, and chemotherapy can be given to limit any potential spread. Colorectal cancer is treatable if caught early, which is why all people age 50 and older should schedule regular screenings for colonoscopy, sigmoidoscopy, and so forth.


Hemorrhoids are swollen blood vessels that can extend from the anus; they look like cushions. Hemorrhoids are often uncomfortable—​itchy, painful, and bleeding bright red blood from the highly vascular circulation supplying the anus and rectum. Risk factors are plentiful and include diarrhea, constipation, heavy lifting, prolonged sitting, and pregnancy.

For most people with hemorrhoids, treatment is non-surgical and includes increasing fiber in your diet and using a salve like Preparation H. Depending on location (internal and external), severity of symptoms, and so forth, surgical options are also available for the treatment of hemorrhoids.


When the cause of bloody stool is obscure, it's likely attributable to angiodysplasia or vascular malformation of the gut. Angiodysplasia is commonly associated with end-stage renal disease, von Willebrand disease, and end-stage renal failure.

Depending on location, angiodysplasia can be treated with endoscopic obliteration. Other treatments include hormone therapy, periodic blood transfusion, and iron supplements. Fortunately, in most people, angiodysplasia stops on its own.

Inflammatory Bowel Disease (IBD)

Inflammatory bowel disease (IBD) is a general term for autoimmune disease that causes inflammation of the bowels. The two most common types of IBD are Crohn's disease and ulcerative colitis.

Therapy or treatment for IBD involves medication, including steroids and immune-modifying agents, and potentially surgery. Thanks to recent drug developments, the number of patients requiring surgery for IBD has significantly decreased.


In 2019, it is estimated that colorectal cancer will be diagnosed in 145,600 people, and 51,020 people will die of the disease. Thanks to earlier detection and treatment, the number of deaths attributable to colorectal disease declined by 25% over the past couple of decades.

Diverticular Disease

There are two types of diverticular disease—diverticulosis and diverticulitis. Both can present with pain and may result in blood in the stool.

Diverticulosis occurs when pouches or diverticula (singular diverticulum) form in the colon. These diverticula grow out of weaknesses in the colonic wall and sometimes grow to several centimeters long. Although classically attributed to a low-fiber diet, the exact cause of such diverticula is unknown. Bleeding from diverticula can be stopped during endoscopy or abdominal surgery.

When diverticula become infected, the condition diverticulitis results. Diverticulitis can be treated in an inpatient or outpatient setting, and antibiotics may be required. If surgery is deemed necessary, physicians usually wait until after the infection has been treated first.

Ischemic Colitis

Ninety percent of all cases of ischemic colitis are in the elderly. The condition can be acute or chronic.

Ischemic injury results when intestinal blood flow to the colon is inadequate (think blood clot or atherosclerosis). In addition to blood in the stool, ischemic colitis can also present as diarrhea, an urgent need to defecate, abdominal pain and vomiting.

Most cases of ischemic colitis last a short time and resolve on their own. With more severe cases, people are hospitalized, put on bowel rest and given intravenous fluids and antibiotics.

About 20% of people who develop ischemic colitis, however, go on to need surgery. Prognosis for those who receive surgery is grim with a mortality rate up to 65%.

False Alarm

Occasionally, pigments and coloring from the food we eat like Kool-Aid, Hawaiian Punch, red gelatin, and even beets, can turn your stool red. You may have witnessed this benign yet disconcerting phenomena after your child eats a red popsicle.

A Word From Verywell

Bloody stool can be caused by many things. Some of these causes are annoying yet pretty harmless like hemorrhoids or anal fissures; other causes are a lot more concerning—like cancer.

If you or a loved one complains of blood in the stool, it's important that you/they see a physician. It's scary to look down and see blood on the tissue or in the bowl, and it may be tempting to ignore it and hope it goes away. However, with colorectal cancer a leading cause of death throughout the world, you shouldn't ignore blood in your stool.

Was this page helpful?
Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Kim BS, Li BT, Engel A, et al. Diagnosis of gastrointestinal bleeding: A practical guide for clinicians. World J Gastrointest Pathophysiol. 2014;5(4):467-78. doi:10.4291/wjgp.v5.i4.467

  2. Saleem S, Thomas AL. Management of Upper Gastrointestinal Bleeding by an Internist. Cureus. 2018;10(6):e2878. doi:10.7759/cureus.2878

  3. Sonnenberg A. Timing of endoscopy in gastrointestinal bleeding. United European Gastroenterol J. 2014;2(1):5-9. doi:10.1177/2050640613518773

  4. Jung K, Moon W. Role of endoscopy in acute gastrointestinal bleeding in real clinical practice: An evidence-based review. World J Gastrointest Endosc. 2019;11(2):68-83. doi:10.4253/wjge.v11.i2.68

  5. MedlinePlus. Anal fissure. Updated June 11, 2018.

  6. Villalba H, Villalba S, Abbas MA. Anal fissure: a common cause of anal pain. Perm J. 2007;11(4):62-5.

  7. Eshghi MJ, Fatemi R, Hashemy A, Aldulaimi D, Khodadoostan M. A retrospective study of patients with colorectal polyps. Gastroenterol Hepatol Bed Bench. 2011;4(1):17-22.

  8. Centers for Disease Control and Prevention. Colorectal cancer statistics. Updated May 28, 2019.

  9. U.S. Preventive Service Task Force. Colorectal cancer: Screening. Updated June 15, 2016.

  10. Lohsiriwat V. Hemorrhoids: from basic pathophysiology to clinical management. World J Gastroenterol. 2012;18(17):2009-17. doi:10.3748/wjg.v18.i17.2009

  11. Muftah M, Mulki R, Dhere T, Keilin S, Chawla S. Diagnostic and therapeutic considerations for obscure gastrointestinal bleeding in patients with chronic kidney disease. Ann Gastroenterol. 2019;32(2):113-123. doi:10.20524/aog.2018.0341

  12. Compagna R, Serra R, Sivero L, et al. Tailored treatment of intestinal angiodysplasia in elderly. Open Med (Wars). 2015;10(1):538-542. doi:10.1515/med-2015-0091

  13. Fakhoury M, Negrulj R, Mooranian A, Al-salami H. Inflammatory bowel disease: clinical aspects and treatments. J Inflamm Res. 2014;7:113-20. doi:10.2147/JIR.S65979

  14. American Cancer Society: Cancer Facts and Figures 2019. Atlanta, Ga: American Cancer Society, 2019.

  15. Haggar FA, Boushey RP. Colorectal cancer epidemiology: incidence, mortality, survival, and risk factors. Clin Colon Rectal Surg. 2009;22(4):191-7. doi:10.1055/s-0029-1242458

  16. National Institute of Diabetes and Digestive and Kidney Diseases. Diverticular disease. Updated May 2016.

  17. Tursi A. Diverticular disease: A therapeutic overview. World J Gastrointest Pharmacol Ther. 2010;1(1):27-35. doi:10.4292/wjgpt.v1.i1.27

  18. Washington C, Carmichael JC. Management of ischemic colitis. Clin Colon Rectal Surg. 2012;25(4):228-35. doi:10.1055/s-0032-1329534

Additional Reading
  • Bullard Dunn KM, Rothenberger DA. Colon, Rectum, and Anus. In: Brunicardi F, Andersen DK, Billiar TR, Dunn DL, Hunter JG, Matthews JB, Pollock RE. eds. Schwartz's Principles of Surgery, 10e. New York, NY: McGraw-Hill; 2014.

  • Gomella LG, Haist SA. Chapter 3. Differential Diagnosis: Symptoms, Signs, and Conditions. In: Gomella LG, Haist SA. eds. Clinician's Pocket Reference: The Scut Monkey, 11e. New York, NY: McGraw-Hill; 2007.

  • Mayer RJ. Chapter 91. Gastrointestinal Tract Cancer. In: Longo DL, Fauci AS, Kasper DL, Hauser SL, Jameson J, Loscalzo J. eds. Harrison's Principles of Internal Medicine, 18e. New York, NY: McGraw-Hill; 2012.

  • Stephan M, Carter C, Ashfaq S. Chapter 50. Pediatric Emergencies. In: Stone C, Humphries RL. eds. CURRENT Diagnosis & Treatment Emergency Medicine, 7e. New York, NY: McGraw-Hill; 2011.

  • Usatine RP, Smith MA, Chumley HS, Mayeaux EJ, Jr.. Chapter 66. Hemorrhoids. In: Usatine RP, Smith MA, Chumley HS, Mayeaux EJ, Jr.. eds. The Color Atlas of Family Medicine, 2e. New York, NY: McGraw-Hill; 2013.