Why Is Your Poop Black and Tarry?

Medically Reviewed by Minesh Khatri, MD on May 27, 2023
4 min read

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.

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.

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.

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


A bleeding ulcer is the most common concerning cause of dark stools. An ulcer is an open sore on the inside of your stomach or small intestine. Sometimes these sores bleed. This can make your poop dark. Blood exposed to gastric acids turns black and tarry (sticky). This is called melena and is a sign of an upper gastrointestinal bleed.

Alcohol and NSAIDs and hpylori increase your risk for gastric ulcers

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

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.

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 a dark color in your vomit or poop
  • Feel weak or dizzy
  • Feel short of breath
  • Have pain in your chest or belly

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 bright red blood in your 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:

  • Blood in your vomit or have black tarry stool
  • Get very dizzy or pass out