Diseases & Conditions A - Z
powered by Talix

Bloody Or Tarry Stools

Bloody or tarry stools refer to a stool sample that’s either dark red or black in color. Bloody or tarry stools can indicate bleeding or other injuries in your gastrointestinal tract. You may also have dark, discolored bowel movements after eating dark-colored foods. Notify your doctor any time you have bloody or black-colored stool to rule out serious medical conditions.

What Causes Black, Tarry Stools?

Black, Tarry Stools

Bleeding in the upper portion of your digestive system can cause black, tarry stools. Ulcers or another form of irritation in your esophagus or stomach known as gastritis can cause bleeding. When the blood mixes with digestive fluids, it takes on the appearance of tar.

Certain medications can also lead to black-colored stools. Iron supplements and bismuth-based medications, for example, can darken your stools.

Sometimes, serious blood and circulation abnormalities in your digestive system can cause black, tarry stools. These can include the following:

  • Bowel ischemia is a reduction of blood flow to the intestines.
  • Vascular malformation is misshapen veins.
  • Varices are large, protruding veins in the intestines.

Red, Bloody Stools

Red or bloody stools can also be due to several different medical conditions. Your stools may be bloody due to bleeding in the lower half of your digestive system. Cancerous or benign polyps on your colon can produce gastrointestinal bleeding in some cases. Inflammatory bowel diseases such as diverticulosis, ulcerative colitis, and Crohn’s disease may cause you to expel bright red or maroon-colored blood in your stool.

A common cause of bloody stools is the presence of hemorrhoids. Hemorrhoids are swollen veins located in your rectum or anus. Straining to produce a bowel movement can cause bleeding.

Blockages at any point in your digestive tract can cause black, tarry, or bloody stools.

Dietary Causes

The foods you eat can cause your stools to appear bloody or tarry. Eating red or black foods can give your feces a dark appearance without the existence of blood.

The following can discolor your bowel movements:

  • black licorice
  • blueberries
  • dark chocolate cookies
  • red-colored gelatin
  • beets
  • red fruit punch

How Is the Cause of Bloody or Tarry Stools Diagnosed?

Your doctor will take a medical history and perform a physical examination to determine the cause of your unusual stool color. They’ll probably order blood tests and a stool sample. Imaging tests such as MRIs, X-rays, and CT scans can help them see the blood flow to your digestive system. These diagnostic tools will reveal any blockages that could be causing gastrointestinal


Your doctor may schedule a colonoscopy to assess the condition of your colon. A colonoscopy often occurs while you’re under sedation. Your doctor will use a thin, flexible tube with a camera on the end to see the inside of your colon and look for the cause of your symptoms.

What Are the Treatment Options for Bloody or Tarry Stools?

The treatment of bloody or tarry stools varies according to the cause of the problem. According to the American Cancer Society, people with cancer who have hemorrhoids can ease the passage of stool and reduce bleeding by using stool softeners under a doctor’s direction. Sitz baths can also ease the pain of hemorrhoids and prevent bleeding.

Your doctor may prescribe acid-reducing medications to treat bleeding ulcers. Antibiotics and immunosuppressant drugs can also calm inflammatory bowel disease and infections.

Vein abnormalities and blockages may require surgical repair if the bleeding doesn’t stop on its own. If you’ve lost a lot of blood through your stool, you may be at risk of developing anemia. You may need a blood transfusion to replenish your supply of red blood cells.

Polyps on your colon that cause bloody stools can indicate precancerous conditions or cancer in some people. Your doctor will determine the appropriate treatment for these conditions. Removal of the polyps may be all that’s necessary in some cases. Other polyps may require radiation therapy and chemotherapy if cancer is present.

How Can I Prevent Bloody or Tarry Stools?

You can help lessen the occurrence of bloody or tarry stools by drinking plenty of water and eating lots of fiber. Water and fiber help soften stool, which can ease the passage of stool from your body. Some foods that have fiber include:

  • raspberries
  • pears
  • whole grains
  • beans
  • artichokes

However, consult your doctor to decide on a high-fiber diet that will work with your underlying cause or condition. For example, berries can be irritating if you have an inflammatory, gastric condition.

Content licensed from:

Written by: Erica Roth
Medically reviewed on: Feb 23, 2016: Debra Sullivan, PhD, MSN, RN, CNE, COI

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
Symptom Search
Enter your symptoms in our Symptom Checker to find out possible causes of your symptoms. Go.
Drug Interaction Checker
Enter any list of prescription drugs and see how they interact with each other and with other substances. Go.
Pill Identifier
Enter its color and shape information, and this tool helps you identify it. Go.
Drugs A-Z
Find information on drug interactions, side effects, and more. Go.

Eating Raw Cookie Dough is Even Riskier, FDA Warns

The FDA issued an official warning regarding the E. coli risk associated with consuming raw cookie dough containing contaminated flour.