Why Is My Poop Black? Causes of 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.

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.

Eating certain dark-colored foods can give you black stools. But it can also occur due to a medical issue that causes bleeding in your upper digestive tract.

Looking down into the toilet bowl and seeing poop that looks a bit different than usual can be a little stressful — but it isn’t always cause for alarm.

If you’ve noticed your stools are looking black and tarry, it could be connected to a more serious issue like bleeding in your gastrointestinal tract. But it could also be due to certain things you’ve been eating.

Read on for some of the reasons your poop might be taking on a darker hue, and when to talk with a doctor.

Dark-colored foods

Sometimes, the simplest reason is the actual reason: If you’ve noticed your poop has gone from its usual brown to a blacker color, it could be due to the sorts of foods you’ve been eating. This is especially true if you haven’t noticed any additional gastrointestinal symptoms.

Some foods that can turn your poop black:

• black licorice
• blueberries
• dark chocolate cookies

Iron supplements

Many people take iron supplements for anemia, a condition in which an individual’s blood has a lower-than-normal amount of red blood cells, causing feelings of tiredness and weakness. These supplements can have a few side effects, including

• nausea
• constipation
• black stools

If you take iron supplements and are having issues with side effects, talk with your doctor. There are a few different types of iron supplements, and some may be easier on your stomach than others.

Medicines containing bismuth

Medicines containing bismuth subsalicylate — like Pepto-Bismol — can turn your stools black. Ingesting too much bismuth subsalicylate over a prolonged period of time can also turn your tongue and teeth black.

Ulcers

Ulcers are open sores on the lining of the digestive tract. While they’re not always painful, they can cause:

• a burning sensation in the stomach
• indigestion
• heartburn
• a general feeling of being unwell

When ulcers start to bleed, they can create more severe symptoms, including black, “sticky,” tarry stools (which are darker in color due to blood mixing with digestive fluids). Because this is a more severe symptom, you should talk with your doctor ASAP if these dark stools are accompanied by any of the manifestations above.

Upper gastrointestinal (GI) bleeding

In addition to ulcers, there are a few other conditions that can cause bleeding in the upper GI tract, which in turn can lead to black, tarry stools. Black stools caused by these kinds of upper GI issues are sometimes referred to as melena. A few of these conditions include:

• gastritis
• esophagitis
• Mallory-Weiss syndrome
• esophageal or stomach cancer

Many of these conditions are serious and include a host of other gastrointestinal symptoms. If your stools have been black and tarry for a few days, and are accompanied by stomach aches and vomiting, you should seek medical help immediately.

Esophageal varices

The esophagus is a tube that carries foods and liquids to the stomach. When veins inside the esophagus become swollen — a condition usually connected to cirrhosis or other advanced liver diseases — they can occasionally rupture and cause both red, bloody stools, or black, tarry stools.

It’s important to call your doctor immediately if you are already aware that you are living with liver disease, and start to experience black stools along with:

• muscle cramps
• stomach discomfort
• rapid weight loss
• jaundice

How is the cause of black stools diagnosed?

If your symptoms are not severe enough to warrant a hospital visit, your doctor will likely ask about your medical history and perform a physical examination to try to determine the cause of your unusual stool color. They’ll probably order blood tests and a stool sample, and may also suggest imaging (like X-rays) to see the inside of your digestive tract.

Your doctor may also schedule a gastroscopy or colonoscopy to assess the condition of your gut.

A colonoscopy is often performed while you’re under sedation. Your doctor will insert a thin, flexible tube through your anus into the rectum with a camera on the end to see the inside of your colon and look for the cause of your symptoms.

A gastroscopy is similar in nature to a colonoscopy but focuses on the esophagus, stomach, and small intestine. The thin tube is inserted through your throat, rather than the anus.

If you need help finding a primary care doctor, then check out our FindCare tool here.

What are the treatment options for black stools?

Treating black stools varies according to what is causing the condition.

If you notice that you’ve been eating a lot of blueberries, blackberries, and other dark foods, limit your intake for a few days and see if it makes a difference.

The same goes for iron supplements and medicines containing bismuth subsalicylate: If you think your black stools may be connected to taking either of these, talk with your doctor about safe alternatives.

Ulcers can have different causes, but milder forms are commonly treated by:

• proton pump inhibitors (PPIs), which reduce the amount of acid in your stomach so the ulcers can heal
• H2 receptor antagonists, which also reduce the amount of acid in the stomach
• over-the-counter antacids
• reduced use of nonsteroidal anti-inflammatory drugs (NSAIDs)

Surgery is also an option for more severe cases of bleeding ulcers.

If your black stools are due to a condition that is causing upper GI bleeding, your treatment will vary depending on the severity of the condition.

Don’t wait to talk with your doctor if your black, tarry stools are accompanied by gastrointestinal discomfort or other intense symptoms — make an appointment right away or head to the nearest ER.

Takeaway

Black stools can be caused by a variety of issues, from eating too much black licorice to bleeding in your gastrointestinal tract. The key to identifying how serious your condition is are the other symptoms that are present.

If you are experiencing nausea, stomach upset, dizziness, or abdominal pain along with black stools, contact your doctor quickly.