Common Black Stool Causes And Symptoms In Adults

causes of black stool

The color and smell of your stool can reveal a lot about your health and diet. Any shade of brown is considered normal and healthy. But here’s the truth: poop can have different colors, ranging from shades of brown and yellow to white, green, and even black.

Black stool can be caused by two main reasons. It could be some dark-colored food or drink you had. Or there’s blood in your poop. If the poop looks black and almost like tar, it could be a sign of a bleeding in the upper gastrointestinal tract. The condition is known as melena and it is considered a medical emergency.


Let’s look at the 6 possible causes of black poop.

1. Dark-Colored Foods

If the color of your food is too dark, the chances to see black poop are high. Here are a few possibilities:

  • Black licorice
  • Blueberries
  • Dark chocolate cookies
  • Fruit punch
  • Blood sausages
  • Prunes
  • Certain veggies like beets and cranberries

2. Iron Supplements Or Other Medicines

You could also experience black stool if you take iron supplements. Because the medicine is high in iron and this leads to a much darker shade of stool. This is the reason why pregnant women (who take iron tablets and other prenatal vitamins) and anemic people (who take iron supplements) might have black poop.

Also, newborns can have black poop initially, because of swallowing traces of their mother’s blood during labor.


Another reason to get black stool is if you frequently consume certain kinds of medication such as anticoagulants or nonsteroidal anti-inflammatory drugs (NSAID).1

3. Peptic Ulcers

Peptic ulcers are a very common problem. These are ulcers that usually develop in the inner lining of your stomach or the small intestine. It could be caused by bacteria, excessive alcohol, smoking, or taking certain medication frequently. One study found out melena is mainly caused by a peptic ulcer.2 Do you have these symptoms of peptic ulcer?


4. Gastritis

Gastritis is a condition when the stomach lining becomes inflamed. The inflammation could last for years if not treated causing a lot of pain and discomfort. Black stool is a common symptom of erosive gastritis – a type of gastritis with little inflammation and formation of ulcers in the stomach lining.

5. Esophageal Varices

Tar-like black stool could be a symptom of esophageal varices. When blood flow to the liver gets blocked, swollen veins in the lower esophagus (close to your stomach) get damaged and bleed out.


6. Cancer

Sometimes malignant tumors could cause black stool. This type of tumor usually targets the esophagus and stomach and this could lead to black stool. Certain types of cancer can lead to a black stool. Colon cancer occurs when cancerous cells start growing from the colon or rectum and spread to other nearby organs. Black stool can also be a symptom of stomach cancer. In this type, healthy cells in the inner lining of the stomach turn cancerous over a period of years.

Symptoms To Look Out For

If you haven’t eaten anything that causes suspicion, check if you have the following symptoms along with black stool.

  • Abdominal pain
  • Nausea
  • Diarrhea
  • Fever
  • Rectal pain
  • Weight loss

If your stool color has changed suddenly without your eating dark foods or taking iron supplements and other medicines, go to a doctor immediately. Black stool caused by a medical reason can get serious if not treated in time.