What Does It Mean if My Stools Are Black?

What Does It Mean if My Stools Are Black?

Seeing black stools in the toilet can be alarming. Fortunately, in most cases, black stools are not a reason to worry as they can often be caused by food or medications. 

Below, the experts at Digestive Disease Consultants of Orange County in Orange County, California explain what conditions could lead to color changes in your stool. Read on to learn about these underlying causes and whether you might need a colonoscopy to get to the bottom of your black stools. 

Common causes of black stools

When you eat black licorice, blueberries, plums, dark beans, or blood sausages, your stools can be a darker shade. Iron supplements, activated charcoal, and medications containing bismuth subsalicylate (such as Pepto-Bismol) can also turn your stools black.

Normally, this isn’t a cause for concern as your stools revert to their normal color over time. 

Health conditions that could cause black stools

However, black stools can sometimes be a sign of an underlying condition that causes bleeding. As blood gets mixed with feces, the feces may turn black. Such conditions include:

Gastric cancer 

If your black stools are accompanied by symptoms such as losing weight without trying, fatigue, indigestion, and nausea, you should speak to our professionals immediately as these may be signs of gastric cancer. 

The good news is that stomach cancer is rare and makes up only 1.5% of the types of cancers diagnosed in the United States. Luckily, when you catch stomach cancer early, your chances of survival are significantly increased. 


Ulcers are sores found on the lining of the stomach, small intestine, or esophagus. When they bleed, the blood mixes with the digestive fluids and can cause stools to look darker or sometimes black. 

If you experience black stools as well as burning in your stomach, chest pain, indigestion, and discomfort, you should contact a medical professional as soon as possible. Untreated bleeding ulcers can lead to blood loss and anemia.

Ulcers are often caused by an H. pylori bacterial infection. Our team uses advanced H. pylori breath testing to assess whether you might have an ulcer. 

Advanced liver disease

Liver disease is often associated with pale-looking stools. However, in advanced stages, liver disease can cause black stools. 

In advanced cirrhosis, the blood can’t pass properly through a severely damaged liver, which causes an increase in blood pressure in the vein that connects the gut to the liver. If you have liver disease and start to notice black stools, contact a doctor as this condition requires immediate medical attention. 


Parasitic infections can be another cause of black stools. Black specks in the stool could be waste from the parasites or their eggs. Our experts may recommend a colonoscopy to look inside your digestive tract and find the cause of your black stools. 

Find out what your black stools may indicate 

Black stools aren’t always a reason to worry. However, to make sure you’re fine, it’s best to contact us and schedule an appointment to determine whether it’s your diet, medications, or an underlying condition causing your symptoms. 

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