Symptoms A-Z

Why Is My Stool Black? 8 Causes of Black Stool Symptoms

What causes black or tarry stools? Most commonly, black stools are caused by eating certain foods or taking supplements like iron. Other less common causes include intestinal blood located in the upper digestive tract. Read below for associated symptoms like black stool and stomach pain, or other causes and treatment options.

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Black and Tarry Stool Symptoms Explained

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

Your black stool can likely be described or accompanied by:

  • Dark stool that is either black or dark red in color [1]
  • Bloating or abdominal swelling [1]
  • Discomfort while defecating [2]
  • Burning sensation
  • Loss of appetite [3]

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 percent 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 [4].

What Makes Your Poop Black

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

Black stool causes related to diet and lifestyle factors include the following.

  • 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 [6,7].
  • Supplements or medication: You can also notice black stool if you are taking iron supplements or bismuth-containing medication [7].

Infectious black stool causes

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 [8].

Other black stool causes

Other causes of black stools include the following.

  • Internal sores: Sores, like peptic ulcers or internal tears, can cause black stool if blood reaches the intestines [9].
  • 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 Black Stool 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.

Normal variation of constipation

Constipation means bowel movements which have become infrequent and/or hardened and difficult to pass.

There is wide variation in what is thought "normal" when it comes to frequency of bowel movements. Anywhere from three times a day to three times a week is considered normal.

As long as stools are easy to pass, laxatives should not be used in an effort to force the body to a more frequent schedule.

Constipation is usually caused by lack of fiber in the diet; not drinking enough water; insufficient exercise; and often suppressing the urge to have a bowel movement.

A number of medications and remedies, especially narcotic pain relievers, can cause constipation.

Women are often affected, due to pregnancy and other hormonal changes. Young children who demand low-fiber or "junk food" diets are also susceptible.

Constipation is a condition, not a disease, and most of the time is easily corrected. If simple adjustments in diet, exercise, and bowel habits don't help, a doctor can be consulted to rule out a more serious cause.

Rarity: Common

Top Symptoms: abdominal pain (stomach ache), nausea, stomach bloating, constipation, constipation

Symptoms that always occur with normal variation of constipation: constipation

Symptoms that never occur with normal variation of constipation: vomiting

Urgency: Self-treatment

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.

Rarity: Uncommon

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

Urgency: Primary care doctor

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.

Rarity: Uncommon

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

Urgency: Emergency medical service

Acute gastritis

When something interferes with the protective mechanisms of the stomach, a range of problems can occur from mild indigestion to deadly bleeding ulcers. Gastritis is an umbrella term for one of the most common problems, inflammation of the stomach lining.

Symptoms include nausea or vomiting,...

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Chronic gastritis

Gastritis is an inflammation of the lining of the stomach. "Chronic" means it is an ongoing condition that never improves.

The stomach normally contains strong acids to break down food. A layer of mucus lines the stomach to protect it. If the mucus lining is not healthy, the stomach itself can become inflamed.

A common cause of damage is the H. pylori bacteria. It spreads through food, water, and shared eating utensils.

Other causes are nonsteroidal anti-inflammatory drugs, such as ibuprofen or aspirin; drinking alcohol; or severe physical stress such as injury or major surgery. It may be also be an autoimmune response.

Symptoms include upper abdominal pain and discomfort, with nausea and vomiting. A medical provider should be seen if symptoms persist, as chronic gastritis can lead to ulcers, anemia, malnutrition, and continuing damage to the stomach.

Diagnosis is made through patient history, physical examination, and sometimes upper endoscopy or x-rays.

Treatment involves medications to reduce the amount of acid in the stomach, and treating any underlying cause such as H. pylori.

Rarity: Common

Top Symptoms: nausea or vomiting, stomach bloating, loss of appetite, moderate abdominal pain, mild abdominal pain

Urgency: Primary care doctor

Colonic neoplasm

Colonic neoplasm means "new tissue" growing in the colon, or large intestine. This neoplasm may be either benign (not cancerous) or malignant (cancer.)

The exact cause of any cancer remains unknown. Risk factors seem to be:

Being over fifty years of age.

  • Family history of the disease.
  • A high-fat, low-fiber diet, typical in the modern world
  • Chronic inflammatory diseases of the colon such as Crohn's disease.
  • Smoking and alcohol use.
  • Diabetes, obesity, and inactivity.

The earliest symptoms are usually polyps, small growths within the colon which can be detected on colonoscopy and removed before they can become cancerous. Later symptoms may be unexplained fatigue; change in bowel habits; persistent abdominal discomfort such as gas or cramps; blood in stool; or rectal bleeding.

Diagnosis is made through colonoscopy and sometimes blood testing.

Treatment is done through surgery, which may be minor or extensive; and through chemotherapy with radiation therapy, usually done before and after surgery. Supportive care to keep the patient comfortable is also an important part of treatment.

Rarity: Rare

Top Symptoms: fatigue, stomach bloating, stool changes, diarrhea, constipation

Urgency: Primary care doctor

Stomach neoplasm

A neoplasm, or tumor, can be benign/non-cancerous, or it can be malignant/cancer. Since benign stomach tumors are mostly harmless polyps that often go unnoticed, the term stomach neoplasm usually refers to stomach cancer. Because stomach cancer usually goes undetected until an advanced st...

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.

Rarity: Uncommon

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

Urgency: Emergency medical service

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.

Rarity: Common

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

Urgency: Wait and watch

How to Treat and Get Rid of Black or Tarry Stools

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].

When it is an emergency

Seek immediate treatment if you are experiencing:

When to see a doctor for professional treatment

If your condition worsens or persists, you will likely require professional 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 [12-14].

At-home treatment and prevention

If your black stool is related to your diet and the problem occurs frequently, consider the following preventative measures [4].

  • 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 [1,4,15].

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 [6].

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 [6].

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

To diagnose this condition, your doctor would likely ask the following questions:

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

The above questions are also covered by our A.I. Health Assistant.

If you've answered yes to one or more of these questions

Take a quiz to find out what might be causing your black stool

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”).

Black Stool Symptom Checker

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  1. Bloody or Tarry Stools. Nicklaus Children's Hospital. Nicklaus Children's Hospital Link
  2. Bleeding From the Bottom (Rectal Bleeding). NHS. Published January 4, 2017. NHS Link
  3. When to Call the Doctor About Digestive Problems. Sutter Health. Sutter Health Link
  4. LaFee S. End Results: What Color is Your Poop and Other Pressing Fecal Matters. UC San Diego Health. Published May 4, 2018. UCSDH 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. Rectal Bleeding. Middlesex Hospital. Middlesex Hospital Link
  7. LaFee S. End Results: What Color is Your Poop and Other Pressing Fecal Matters. UC San Diego Health. Published May 4, 2018. UCSDH Link
  8. Rotavirus. Mayo Clinic. Published January 4, 2018. Mayo Clinic Link
  9. Rectal Bleeding: Possible Causes. Cleveland Clinic. Published January 27, 2015. Cleveland Clinic 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

Disclaimer: The article does not replace an evaluation by a physician. Information on this page is provided as an information resource only, and is not to be used or relied on for any diagnostic or treatment purposes.