Black stool causes, symptoms, and treatments

black tarry stoolBlack stool can result from dietary changes and could even reveal a serious medical condition, so it’s important to pay attention if you’re seeing black after a bathroom trip. Along with a change in color, black stool may also be tarry in texture and more foul-smelling, which is a clear signal of a serious underlying gastrointestinal problem.

Causes of Black Tarry Stool

False Melena: False melena is black tarry stool caused by food, supplements, medications, or minerals. Iron supplements can trigger false melena, along with foods that are blue, black, or green in color. Some examples of factors that can trigger false melena include black licorice, blueberries, iron supplements, lead, and bismuth.


Melena: This is a result of upper gastrointestinal bleeding in the esophagus, stomach, or small intestine. Other causes of melena include bleeding ulcer, gastritis, esophageal varices, or a Mallory-Weiss tear – this is a tear of the mucous membrane that connects the esophagus and stomach.

Hematochezia: This is the passage of black tarry stool when bleeding is present in parts of the lower digestive tract, such as the colon, rectum, or anus.

Diet: Certain foods can cause stool to appear black or tarry. These foods include black licorice, blueberries, dark chocolate cookies, red-colored gelatin, beets, and red fruit punch.

Medications and Supplements: Common over-the-counter medications to treat the digestive system or diarrhea which contain bismuth can cause stool to appear black. Iron supplements are another common cause of black stool.

Other Causes: Other causes of maroon or black-colored stool are anal fissures, diverticulosis, hemorrhoids, inflammatory bowel disease, infection of the intestines, and trauma or foreign bodies.

Signs and Symptoms of Black Poop

Signs and symptoms of black poop often relate to its underlying cause. Here is a list of potential signs and symptoms that may accompany black tarry poop:

  • Abdominal pain and cramping
  • Bloating or abdominal swelling
  • Changes in bowel habits
  • Diarrhea
  • Gas or indigestion
  • Flu-like symptoms
  • Foul-smelling stool
  • Nausea and vomiting
  • Poor appetite
  • Rectal pain and burning sensation
  • Unexpected weight loss

Diagnosing Black Stool

To properly diagnose the underlying cause of your black tarry stool, your doctor will do a complete medical examination. They will run blood tests and imaging scans to determine any infection, blockages, or anything else that can contribute to black tarry stool.

A colonoscopy or endoscopy may also be recommended to have a better look at the stomach and colon to check for any tears, polyps, or other sources of bleeding.

Treating Black Stool

Treatment for black tarry stool depends on the underlying cause. Some possible treatments for black tarry stool include antibiotics to combat infections, acid-reducing medications to treat ulcers, surgery for abnormal veins, removal of polyps, or simple diet changes like avoiding foods which can cause the stool to appear black or tarry.

How to Prevent Black Stool


If black tarry stool is caused by your diet, you may wish avoid foods that are blue, black, or green in color. You will also want to increase your fiber intake to reduce tears in the colon. Ingest more raspberries, pears, whole grains, beans, and artichokes.

For some conditions, a high-fiber diet is not recommended. Your doctor will help you find the best way to eat based on your unique needs.

Related: Floating poop (steatorrhea): Understand why your stool floats

Author Bio

Mohan Garikiparithi got his degree in medicine from Osmania University (University of Health Sciences). He practiced clinical medicine for over a decade before he shifted his focus to the field of health communications. During his active practice he served as the head of the Dept. of Microbiology in a diagnostic centre in India. On a three-year communications program in Germany, Mohan developed a keen interest in German Medicine (Homoeopathy), and other alternative systems of medicine. He now advocates treating different medical conditions without the use of traditional drugs. An ardent squash player, Mohan believes in the importance of fitness and wellness.


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