Why Is My Poop Black?

Causes and Treatments for Black or Tarry Stool

Black poop often happens after consuming certain medications, supplements, or dark foods like beets or black licorice. While black poop isn't always something to worry about, it can occasionally be a sign of a serious underlying health condition, such as liver disease.

To rule out a life-threatening condition, contact your healthcare provider right away if:

  • You have a history of gastrointestinal (GI) bleeding
  • Your stool has an especially foul smell
  • You have abdominal pain or any other unusual symptoms
  • The problem lasts longer than a few days

This article explores the causes of black or tarry stool. It explains some of the more serious health problems associated with it and outlines common treatments for black stool caused by medical conditions.

An illustration with causes of black stool

Illustration by Michela Buttignol for Verywell Health

Quick Facts About Black Stool

  • Most cases of black stools are from eating black foods or iron supplements.
  • Black stool due to blood indicates a problem in the upper GI tract.
  • Blood in the stool can be detected through a stool test.
  • See your healthcare provider immediately if you have black stool with pain, vomiting, or diarrhea.
  • If you suspect there is blood in your stool, contact your healthcare provider as soon as possible.

Dark Foods

If you have recently eaten a large portion of dark or black-colored foods, it's only natural for your poop to look black, too.

Some foods or ingredients may be more likely than others to make your poop look black, such as:

  • Black licorice
  • Blueberries
  • Blood sausage
  • Beets
  • Dark beer
  • Red food coloring
  • Dark chocolate

If you notice black stool after eating one of these foods, and you are not experiencing any other new or unusual symptoms, wait and see if the stool color returns to normal after a few bowel movements. If it doesn't, reach out to your healthcare provider.

Medications or Supplements

Black stools could be caused by supplements, medication, or minerals.

If you suspect that your poop is black due to a medication or supplement you are taking, call your healthcare provider. Your provider will tell you whether this side effect is normal or you should be seen for an evaluation.

Iron Supplements

Iron supplements, which healthcare providers sometimes prescribe to treat iron deficiency or anemia, are known to cause black stools. This effect is normal, and does not mean there is blood in your poop.

The phenomenon occurs when iron that has not been absorbed in your gut mixes with the microbiome in your digestive tract, causing your stool to turn a black color.

While black-looking stool is common with iron supplements, black and tarry stool is not. If your stool has a texture similar to coffee grounds or has red streaks in it, contact your healthcare provider immediately.

Bismuth

Bismuth subsalicylate, the main active ingredient in Peptol-Bismol, turns into bismuth sulfide when it mixes with the sulfur in your digestive track. Bismuth sulfide is black, and as it passes through your digestive black, it can turn your stool black as well.

This reaction is more likely to happen if you have recently eaten a lot of sulfur-rich foods, like broccoli, kale, onions, or garlic. In some places, the water supply also has a high concentration of sulfur.

Black poop due to bismuth is common. Again, it does not mean there is blood in your poop. Nonetheless, it's always a good idea to contact your healthcare provider if you aren't sure whether your black poop and medication are related.

Blood in the Stool (Melena)

Blood that comes from the upper GI tract—such as the esophagus or the stomach—may turn the stool black. This is a condition called melena. If you have melena, you may also notice that your stool has a tarry texture or is similar to coffee grounds.

Blood changes from red to black as it passes through the body and interacts with enzymes, substances that help digest food in the GI tract. This makes it a bit more difficult to tell if there is red blood in or on the stool.

Bright red blood in or on the stool is typically blood from the lower GI tract, such as the rectum or the colon. This is a condition called hematochezia. Blood stemming from this region will be redder in appearance because it will be exposed to less of the digestive process.

If the black stool appears tarry, or you also have other symptoms such as fainting or near-fainting, dizziness, pain, or vomiting, contact a healthcare provider immediately. This could be a medical emergency.

Some people are more likely to develop bleeding in the GI tract. Talk to your doctor if any of these risk factors apply to you:

  • Chronic vomiting
  • Alcoholism
  • Use of NSAIDs (non-steroidal anti-inflammatory drugs), including aspirin, Advil (ibuprofen), and Aleve (naproxen)
  • Use of anticoagulants (drugs that prevent blood clots)
  • Recent gastrointestinal surgery

Ulcer

An ulcer is a type of sore on the stomach lining that can cause bleeding and melena. Contrary to popular belief, stomach ulcers are not usually caused by stress or spicy food, although these can aggravate an already existing ulcer.

In fact, stomach ulcers are usually caused by an infection with bacteria called Helicobacter pylori (H. pylori). Long-term use of NSAIDs is another cause of stomach ulcers.

NSAIDs can irritate the stomach by weakening the lining's ability to resist acid made in the stomach. For this same reason, NSAIDs have an adverse effect on Crohn's disease and ulcerative colitis—conditions that cause ulcers and inflammation of the GI tract.

Stomach ulcers caused by an infection may be treated with antibiotics. Your healthcare provider may also recommend an acid reducer. Ulcers from NSAIDs usually heal after you stop taking the drug.

Gastritis

Gastritis is inflammation of the stomach lining. This inflammation can be caused by too much alcohol, eating spicy foods, smoking, infection with bacteria, or prolonged use of NSAIDs. Gastritis can also develop after surgery or trauma or may be associated with already existing medical conditions.

Left untreated, gastritis can lead to stomach ulcers and other complications. Some people have no symptoms. Acute, suddenly occurring cases of gastritis may only result in tarry, black stool.

Persistent bleeding can lead to more severe symptoms like:

  • Abdominal pain
  • Lightheadedness
  • Nausea
  • Vomiting
  • Indigestion

If your doctor suspects gastritis, they may prescribe:

  • Antacids or proton pump inhibitors
  • Antibiotics that treat H. pylori infection
  • Sucralfate (a drug that helps the stomach heal by soothing irritation)

If these treatments fail to resolve your symptoms, your healthcare provider may order an upper endoscopy to take a closer look at your stomach and small intestine.

Esophageal Varices

Esophageal varices are enlarged veins in the wall of the lower esophagus or upper stomach. When these veins rupture, they may cause bleeding and lead to blood in the stool or in vomit.

Esophageal varices are serious complications resulting from high blood pressure brought on by cirrhosis of the liver.

Most people with esophageal varices experience no symptoms unless the veins rupture. Symptoms of bleeding (ruptured) esophageal varices include:

  • Melena
  • Vomiting blood
  • Lightheadedness
  • Fainting

Bleeding esophageal varices require immediate medical care to stop the bleeding, as they can lead to sudden death.

Elastic bands may be wrapped around the varices to stop the flow of blood. Stents, tubes inserted to manage blood flow, may be used to lower blood pressure. That can reduce the amount of bleeding.

Mallory-Weiss Tear

Mallory-Weiss tear is a tear in the mucous membrane that joins the esophagus and the stomach. If this tear bleeds, it can result in melena.

This condition is fairly rare. It only only occurs in about seven out of 100,000 people in the US and may be caused by violent vomiting, coughing, or epileptic convulsions. About 5% of people with a Mallory-Weiss tear do not survive.

Like other conditions that cause melena, symptoms of a Mallory-Weiss tear may not be obvious. Along with tarry, black stool, some people may experience any of the following:

  • Vomiting tarry blood
  • Lightheadedness (presyncope)
  • Shortness of breath (dyspnea)
  • Diarrhea
  • Abdominal pain
  • Chest pain

In the case of a Mallory-Weiss tear, the tear heals on its own for most people.

If it doesn't resolve itself, you may need treatment to seal the lesion. This may either take the form of a medication injected internally, or a heat therapy known as electrocoagulation.

Liver Diseases

Liver disease can damage the veins that move blood into the liver. This can cause pressure to build up in the veins, eventually causing them to burst. When this happens, you may vomit blood or have black, tarry stool.

Gastrointestinal bleeding is considered a sign of end-stage liver disease, along with bleeding from the nose and gums. This bleeding can be life-threatening, so you should see an emergency medical provider right away.

Other signs of end-stage liver disease include:

  • Jaundice (yellowing of the skin and eyes)
  • Confusion or other mental difficulties
  • Swelling in the belly, arms, or legs
  • Severe fatigue
  • A tendency to bleed easily

Treatment involves managing the specific complications that often arise in end-stage liver disease, and a liver transplant is critical. Unfortunately, not everyone who is placed on the waiting list for a liver transplant survives long enough to receive a new liver.

When to See a Healthcare Provider

If your stool is black and tarry, it means there is blood in your stool. This is a medical emergency. Even if you are not sure about the appearance of your stool, it's better to get immediate medical attention rather than wait it out.

In addition to black, tarry stool, other symptoms that mean you should see a healthcare provider immediately include:

  • Feeling faint or passing out
  • Shortness of breath
  • Abdominal pain
  • Vomiting blood
  • Unintended weight loss

Sometimes, black stool is simply a result of food you ate or supplements you took. If you think that could be the case, stop consuming the food or supplement. If your stool does not return to its normal color within a few bowel movements, contact your healthcare provider.

Diagnosis

Seeing the black color is not enough to determine whether or not there's blood in your stool. Remember, it could be caused by food or iron supplements. A healthcare provider needs to confirm if there's blood. That requires several types of tests.

Your provider will have you collect a small stool sample at home using a special kit. The sample is then sent to a lab for evaluation.

If you're diagnosed with melena, doctors may order further diagnostic tests to determine the cause and the exact location of the bleeding.

Specifically, your doctor may conduct an esophagogastroduodenoscopy (EGD, or upper endoscopy). This procedure involves inserting a flexible tube with a camera down your throat so that your healthcare provider can inspect the lining of the esophagus, stomach, and upper intestine.

Aside from an esophagogastroduodenoscopy (EGD), other tests that might be done include:

  • X-rays
  • Blood tests
  • Colonoscopy (an internal examination of your large intestine)
  • Stool culture (a test that looks for bacteria in a sample of your stool)
  • Barium studies (X-rays taken after a chalky liquid is ingested)

Summary

Black stool isn't always a sign of a bigger health problem. Your poop may look black as a result of food you ate or iron supplements you took. If that's the case, the color of your poop will return to normal within a day or so.

If it doesn't, and if you cannot trace it back to something you have eaten, ask yourself:

  • Does the stool have a tarry appearance or look somewhat like coffee grounds?
  • Is there an especially foul smell that has not gone away?
  • Does my medical history place me at risk for gastrointestinal bleeding?

If you answered yes to one or more of these questions, or if you're experiencing symptoms like nausea, vomiting, or lightheadedness, you should see a healthcare provider right away.

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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.
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By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.