Black poop often has harmless causes such as medications, supplements, or dark foods like beets or black licorice.
While black poop isn't always something to worry about, it can occasionally be an indication that there is blood in your upper gastrointestinal system. This could mean a serious underlying health condition such as liver disease or cancer.
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When should you worry about black stool?
If your stool is black and tarry (a sticky consistency), it means there is blood in it. This is a medical emergency.
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
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, contact 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. They will tell you whether this side effect is normal or if 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
Bismuthsubsalicylate, 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 foul smell and a tarry texture or is similar to coffee grounds.
If your stool is black but you don't see blood in it, it may still be melena. This is because melena does not look like blood. 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 gastrointestinal bleeding. 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
Bleeding 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 muchalcohol, 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 in the esophagus 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 occurs in about sevenout of 100,000 people in the U.S. 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.
Upper GI Cancers
Cancers that cause gastrointestinal (GI) bleeding such as esophageal cancer or stomach cancer can also have black, tarry stools as a symptom. These cancers often have other symptoms such as:
- Swallowing problems
- Indigestion or heartburn
- Unintentional weight loss
- Fatigue
- Pain in the chest or stomach
- Coughing
- Nausea of vomiting
Cancer is typically treated with chemotherapy or radiation therapy and/or surgery.
How do you fix black poop?
If black stool is caused by something you ate or a medication you're taking, you can get rid of it by discontinuing the food or medication. If your black stool is caused by a medical problem, treating the underlying condition may improve this symptom. This is why it's important to see a healthcare provider if you have black stool that doesn't resolve on its own within a few days.
Diagnosis
Color alone s 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 healthcare provider may conduct an esophagogastroduodenoscopy(EGD, or upper endoscopy). This procedure involves inserting a flexible tube with a camera down your throat so that they 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 your poop has a tarry appearance, looks like coffee grounds, or has a foul smell, see your healthcare provider. You should also see a healthcare provider if your poop is black and you are at high risk for gastrointestinal bleeding or if you have other symptoms such as nausea, vomiting, or lightheadedness.
