Why Is Your Poop Black and Tarry?

If you notice your poop is black or tarry, it might be due to something as simple as a change in your diet or a new medicine you're taking. Sometimes, though, it's a sign of a medical problem that you don't want to ignore.

Even if you think you know why it's happening, always call your doctor if you have black, tarry stools.

Iron Supplements

Black poop can be a side effect of iron pills you take for anemia -- a condition that happens when you don't have enough red blood cells to carry oxygen around your body.

Other side effects of iron supplements are:

Tell your doctor if you notice any problems after you take iron supplements. You may need to stop or switch to a different type.

Dark-Colored Foods

Sometimes dark-colored foods turn your poop black. These include:

  • Black licorice
  • Chocolate sandwich cookies
  • Blueberries
  • Grape juice
  • Beets

The dark color should go away once you stop eating the food that caused it.

Medicines With Bismuth

Drugs for upset stomach like bismuth subsalicylate (Pepto-Bismol and Kaopectate) contain bismuth to calm your belly. Bismuth can turn your tongue and poop black.

This symptom is harmless. It should go away once you stop taking the medicine. Call your doctor and stop taking it if you:

  • Have a ringing or buzzing sound in your ears or can't hear
  • Feel worse after taking bismuth

Bleeding Ulcer

A bleeding ulcer is the most common cause of dark stools. An ulcer is a sore on the inside of your stomach or small intestine. Sometimes these sores bleed. This can make your poop dark.

Other signs that you have an ulcer include:

  • Burning pain in your belly
  • Swollen belly
  • Burping
  • Heartburn
  • Nausea, throwing up, or having vomit that looks like coffee grounds

Some medicines for ulcers lower the amount of acid in your stomach. Others coat and protect it from the damage that stomach acids can cause.

Call your doctor if you:

  • See blood in your poop or vomit
  • Have trouble breathing
  • Feel like you're about to pass out
  • Have lost weight without trying
  • Lose your appetite

Continued

Esophageal and Gastric Cancers

If you have bleeding in the upper GI tract -- the esophagus, stomach, and duodenum -- you could have black, tarry stools that are called melena. It could be a sign of esophageal and gastric cancers.

Some other symptoms of esophageal cancer are:

If you have gastric (stomach) cancer, you could have symptoms like:

  • Feeling tired
  • Being bloated after you eat
  • Severe heartburn or indigestion
  • Nausea or vomiting
  • Pain in your stomach
  • Losing weight when you're not trying to

Treatment for these cancers depends on the stage of the disease and how far it's spread. Options can include surgery, chemotherapy, or radiation.

Mallory-Weiss Tear

Intense coughing or vomiting can tear the esophagus and make it bleed, a condition called a Mallory-Weiss tear.

Other symptoms you might get are:

Most tears heal on their own. If yours doesn't, your doctor can use a heat treatment or give you medicine to stop the bleeding.

Call your doctor if you:

  • See blood in your vomit or poop
  • Feel weak or dizzy
  • Have trouble breathing
  • Have pain in your chest or belly

Esophageal Varices

Varices are swollen veins in the esophagus -- the tube that your food travels down to get from your throat to your stomach. These abnormal veins can sometimes leak blood or break open. They're more common in people with liver disease.

If varices are the cause of your black stools, you might also have symptoms like:

  • Yellow skin and eyes
  • Bruises
  • Swollen belly
  • Throwing up blood
  • Dizziness
  • Fainting

Bleeding in your esophagus is an emergency that needs treatment in a hospital. The treatment usually involves getting medicine through an IV to lower the pressure in the veins or a procedure called an endoscopy to tie off the veins to stop the bleeding.

Call your doctor if you:

  • See blood in your vomit or poop
  • Get very dizzy or pass out

WebMD Medical Reference Reviewed by Sabrina Felson, MD on May 04, 2019

Sources

SOURCES:

American Cancer Society: "What Is Colorectal Cancer?"

Cedars-Sinai: "Mallory-Weiss Tear."

Cleveland Clinic: "Esophageal Varices," "Oral Iron Supplementation."

Continence Foundation of Australia: "Bristol stool chart."

GI Society: "The Scoop on Poop."

Johns Hopkins Medicine: "5 Things Your Poop Can Tell You About Your Health."

KnowYourOTCs.org: "Bismuth Subsalicylate."

Mayo Clinic: "Colon cancer: Symptoms & causes," "Esophageal varices: Symptoms & causes," "Gastritis: Symptoms & causes," "Peptic Ulcer: Symptoms & causes," "Stool color: When to worry," "Esophageal cancer," "Stomach cancer."

MD Anderson Cancer Center: "Colorectal cancer symptoms: When to talk to your doctor."

National Institute of Diabetes and Digestive and Kidney Diseases: "Treatment for Peptic Ulcers (Stomach Ulcers)."

Nicklaus Children's Hospital: "Bloody or tarry stools."

Seattle Children's Hospital: "Stools -- Unusual Color."

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