Read below about black stool, including causes, treatment options and remedies. Or get a personalized analysis of your black stool from our A.I. health assistant. At Buoy, we build tools that help you know what’s wrong right now and how to get the right care.

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Black Stool Symptoms

Not everyone talks about it, but everybody does it. Bowel movements can vary in appearance but there are instances that might leave you a bit concerned with what's going on in those intestines of yours.

Black stool symptoms can be serious but often, there is a simple explanation for the change of your stool's appearance. Sometimes, the change is associated with your diet. But if you notice a consistent dark shade staring back at you from your toilet bowl, you should begin trying to discover the cause of the discoloration.

Here's what to expect if you're experiencing black tarry stool symptoms:

  • Dark stool that is either black or dark red in color [6]
  • Bloating or abdominal swelling [6]
  • Discomfort while defecating [7]
  • Burning sensation
  • Loss of appetite [8]

What determines the color of your stool? The shade reflects what's happening internally.

The body does a great job of making sure that every morsel we eat is turned into useful energy. Most bowel movements consist of one-part solid waste and three parts water. Most of the time, bacteria make up about one third of the solid portion. Another third is indigestible matter. The remaining 40% is a grab-bag of waste, fat, red blood cells, and bile. The ideal combination of these components gives you a distinctive brown shade.

But when these ratios are thrown off, whatever the cause, the shade of your stool changes. Black stool typically signals an excess of blood. But before you panic, consider the variety of causes connected to black stool symptoms. [9]

Black Stool Causes

Though there are some serious causes, most cases of black stool can be traced to diet changes, viruses, or other non-life-threatening causes.

Diet and lifestyle:

  • False Melena: A black stool is a false melena if it is caused by eating certain food such as black licorice, blueberries, cranberries, beets, prunes, dark chocolate cookies, or blood sausages. [1,2]
  • Supplements or medication: You can also notice black stool if you are taking iron supplements or bismuth-containing medication. [2]

Infectious black stool causes:

  • Viral infections: Rotavirus, one type of a viral infection, can cause acute gastroenteritis (inflammation of the stomach and intestines.) This can lead to severe diarrhea with black tarry stools, especially in infants and children. [3]

Other black stool causes:

  • Internal sores: Sores, like peptic ulcers or internal tears, can cause black stool if blood reaches the intestines. [4]
  • Internal bleeding: Trauma, like a car accident, can cause internal bleeding. Depending on the location of the bleeding, black stool can be a symptom. [5]

9 Possible Conditions

The list below shows results from the use of our quiz by Buoy users who experienced black stool. This list does not constitute medical advice and may not accurately represent what you have.

  1. 1.Normal Variation of Constipation

    Constipation is a very common condition affecting the large intestine. It is characterized by difficulty passing stool, or passing stool less often. Commonly it is linked to not eating enough dietary fiber, not drinking enough fluids, or not getting enough exercise. Some medications can cause constipation as well.

    Variable, but can resolve in days to weeks

    Top Symptoms:
    abdominal pain (stomach ache), nausea, stomach bloating, constipation, constipation
    Symptoms that always occur with normal variation of constipation:
    Symptoms that never occur with normal variation of constipation:
  2. 2.Stomach Ulcer

    A peptic ulcer is a sore in the lining of the stomach or the first part of your small intestine (the duodenum), which causes pain following meals or on an empty stomach.

    2-4 weeks with treatment

    Top Symptoms:
    fatigue, nausea, loss of appetite, moderate abdominal pain, abdominal cramps (stomach cramps)
    Symptoms that never occur with stomach ulcer:
    pain in the lower left abdomen
    Primary care doctor
  3. 3.Upper Gastrointestinal Bleeding

    The digestive, or gastrointestinal (GI), tract includes the esophagus, stomach, small intestine, large intestine, rectum, and anus. Upper GI bleeding is a medical emergency involving internal bleeding from the esophagus, stomach, or the small intestine.

    Several days to weeks of recovery in the hospital.

    Top Symptoms:
    fatigue, being severely ill, abdominal cramps (stomach cramps), lightheadedness, rectal bleeding
    Symptoms that always occur with upper gastrointestinal bleeding:
    vomiting (old) blood or passing tarry stools, being severely ill
    Emergency medical service
  4. 4.Acute Gastritis

    Acute gastritis is the sudden onset of nausea, vomiting, and/or upper abdominal pain that's caused by inflammation of your stomach lining. If it doesn't go away, this can become an ulcer. Causes include taking a medication that affects the stomach, an infection by a bug called, "H. Pylori", or your immune system reacting to yourself.

    Prognosis is great with the appropriate treatment

    Top Symptoms:
    nausea or vomiting, nausea, stomach bloating, loss of appetite, mild abdominal pain
    Symptoms that never occur with acute gastritis:
    Primary care doctor

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  5. 5.Chronic Gastritis

    Chronic gastritis is longterm inflammation of your stomach. If it doesn't go away, this can become an ulcer. Causes include taking a medication that affects the stomach, an infection by a bug called, "H. Pylori", or your immune system reacting to yourself

    With appropriate treatment, prognosis is very good.

    Top Symptoms:
    nausea or vomiting, stomach bloating, loss of appetite, moderate abdominal pain, mild abdominal pain
    Primary care doctor
  6. 6.Colonic Neoplasm

    Colonic neoplasm is a disorder of the large intestine. It often causes abdominal pain, cramping, changes in bowel habits, and fatigue.

    The treatment & prognosis for colonic neoplasm are variable and dependent on the disease severity.

    Top Symptoms:
    fatigue, stomach bloating, stool changes, diarrhea, constipation
    Primary care doctor
  7. 7.Stomach Neoplasm

    Stomach neoplasm is a disease affecting that stomach that impairs it's ability to function properly.

    The treatment & prognosis for stomach neoplasm vary and are dependent on the disease severity.

    Top Symptoms:
    abdominal pain (stomach ache), nausea, loss of appetite, constipation, diarrhea
    Primary care doctor
  8. 8.Acute Variceal Hemorrhage

    Acute variceal hemorrhage is a condition that can occur secondary to (as a result of) liver disease. Blood vessels bringing blood from the digestive tract back to the heart which course through the esophagus (a muscular tube that carries food from the mouth to the stomach) become dilated. In acute variceal hemorrhage, these vessels burst, resulting in internal bleeding.

    Full recovery from hemorrhage is expected within 6 weeks.

    Top Symptoms:
    being severely ill, abdominal pain (stomach ache), vomiting, constipation, lightheadedness
    Symptoms that always occur with acute variceal hemorrhage:
    being severely ill, vomiting (old) blood or passing tarry stools
    Emergency medical service
  9. 9.Non Specific Stool Change

    There are many factors affecting the appearance of someone's stools. Often a variation in stool color and/or consistency is caused by food or medicines. Leafy greens and certain vegetables like spinach and kale can make stool look green. Iron supplements and medicines containing bismuth like Pepto-bismol can turn stools black. It looks like your stool change is probably a variation of normal.

    A few days

    Top Symptoms:
    black stool, green poop, dark brown stool, red stool
    Symptoms that never occur with non specific stool change:
    tarry stool, weight loss, rectal bleeding, fever
    Wait and watch

Black Stool Treatments, Relief and Prevention

It is imperative to seek medical help immediately if you have an illness accompanied by black tarry stool. In some cases, a colonoscopy or endoscopy is recommended to have a better look at the stomach and colon to check for any tears, polyps, or other bleeding sources. Unless you are certain that your dark stool is being caused by your diet, a doctor's visit is recommended. [1,6]

Seek immediate treatment if you are experiencing:

If your condition requires treatment, there are two main options.

  • Medications: Doctors may give you antibiotics or acid-reducing medications depending on the underlying cause.
  • Surgery: Aside from treating abnormal veins, surgery is required to remove polyps or any parts of the colon damaged by cancer or inflammatory bowel disease. [12,13,14]

If your black stool is related to your diet and the problem occurs frequently, consider the following preventative measures. [9]

  • Always drink plenty of water: Skip sugary drinks and stick with water.
  • Avoid food that is blue, green, or black in color: The dyes, whether natural or manmade, can alter the color of your stool.
  • Eat food rich in fiber: Increase your fiber intake by eating raspberries, pears, whole grains, beans, and artichokes to reduce tears in the colon.

We sometimes don't give bowel movements a second thought as they are a part of life. But if we start to pay attention to what our black stool symptoms are trying to tell us, we can combat underlying health problems and complications as early as possible.

FAQs About Black Stool

Here are some frequently asked questions about black stool.

Can different foods/drinks cause black stool?

Yes, the following foods can cause black stool: black licorice, blueberries, iron supplements, lead, and pepto-bismol, and charcoal. Furthermore, beets may cause a dark or black is stool, though usually coloration from the beets may clue observers into the origin of the color. Iron supplements and dark leafy vegetable can also darken stool as well as foods that contain blood like blood sausage or blood pudding. Dark beers and lagers may also significantly darken stool. 6,9,15

Can black stool be caused by dehydration?

No, dehydration does not cause black stool if it is not accompanied by gastrointestinal bleeding. Dehydration may cause sparse, hard pebble-like stools, it may also darken the color of the stool. Black stools are noticeably darker than the dark brown or dark green stools that accompany dehydration, and should be taken seriously as a sign of internal bleeding if there is no other obvious cause. 16

Why is stool black sometimes?

Stool is black because a dark colored food, or a food that becomes dark when exposed to stomach acid or bile has been consumed (see list above). Aside from food, most healthcare professionals are concerned because digested blood is black and tarry in appearance. [1]

Is it normal for a person to have black stool?

If someone has eaten a food that is known to cause black stool and is not at risk of internal bleeding caused by medication, they may not be at risk. If they have black stool with no explanation or have a bleeding disorder or predisposition toward gastrointestinal bleeding, then black stool should be considered abnormal. [1]

Can black stool be caused by stress?

No. Black stool cannot be caused by stress. It is possible for stress to cause an ulcer, for that ulcer to bleed, and for that blood to darken stool, but this is relatively uncommon. Stress in the absence of other conditions, does not cause black stools. Conditions that cause black stool, however, can cause stress or place stress on the body. A bleed in the gut can also cause fatigue and irritability in some. [17]

Questions Your Doctor May Ask About Black Stool

  • Q.Have you experienced any nausea?
  • Q.Have you been feeling more tired than usual, lethargic or fatigued despite sleeping a normal amount?
  • Q.Any fever today or during the last week?
  • Q.Have you had any changes in your weight?

If you've answered yes to one or more of these questions, try our black stool symptom checker to find out more.

Black Stool Quiz

Black Stool Symptom Checker Statistics

  • People who have experienced black stool have also experienced:

    • 16% Abdominal Pain (Stomach Ache)
    • 8% Diarrhea
    • 7% Nausea
  • People who have experienced black stool were most often matched with:

    • 58% Upper Gastrointestinal Bleeding
    • 33% Stomach Ulcer
    • 8% Normal Variation of Constipation
  • Source: Aggregated and anonymized results from visits to the Buoy AI health assistant (check it out by clicking on “Take Quiz”).

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  1. Rectal Bleeding. Middlesex Hospital. Middlesex Hospital Link.
  2. LaFee S. End Results: What Color is Your Poop and Other Pressing Fecal Matters. UC San Diego Health. Published May 4, 2018. UCSDH Link.
  3. Rotavirus. Mayo Clinic. Published January 4, 2018. Mayo Clinic Link.
  4. Rectal Bleeding: Possible Causes. Cleveland Clinic. Published January 27, 2015. Cleveland Clinic Link.
  5. Saeb-Parsy K, Omer A, Hall NR. Melaena as the Presenting Symptom of Gastric Mucosal Injury Due to Blunt Abdominal Trauma. Emergency Medical Journal. 2006;23(5):e34. BMJ Link.
  6. Bloody or Tarry Stools. Nicklaus Children's Hospital. Nicklaus Children's Hospital Link.
  7. Bleeding From the Bottom (Rectal Bleeding). NHS. Published January 4, 2017. NHS Link.
  8. When to Call the Doctor About Digestive Problems. Sutter Health. Sutter Health Link.
  9. LaFee S. End Results: What Color is Your Poop and Other Pressing Fecal Matters. UC San Diego Health. Published May 4, 2018. UCSDH Link.
  10. Borke J, Zieve D, Conaway B, et al. Bleeding. National Library of Medicine: MedLinePlus. Published October 16, 2017. MedLinePlus Link.
  11. Indications of Post Op Bleeding or Signs of Post Op Bleeding. Act For Libraries. Act For Libraries Link.
  12. Bowel Polyps. NHS. Published July 9, 2017. NHS Link.
  13. Colon Cancer. UCSF Department of Surgery. Published August 17, 2018. UCSF Department of Surgery Link.
  14. Sica GS, Biancone L. Surgery for Inflammatory Bowel Disease in the Era of Laparoscopy. World Journal of Gastroenterology. 2013;19(16):2445-2448. WJG Link.
  15. Should Your Child See a Doctor? Stools - Unusual Color. Seattle Children's. Published March 19, 2018. Seattle Children's Link.
  16. Constipation. John Hopkins Medicine. John Hopkins Medicine Link.
  17. Symptoms & Causes of GI Bleeding. National Institute of Diabetes and Digestive and Kidney Diseases. Published July 2016. NIDDK Link.