Why Your Poop Is Black and What To Do About It

By Alicia Wooldridge, MD
Medically reviewed checkmarkMedically reviewed
April 19, 2022

It can be quite alarming to notice that your stool is black—but try not to panic. It could be as simple as the last meal you ate! 

That’s right: There are many foods—and some supplements—that can turn your poop black.

This is actually the most typical reason for a change in stool color.

There are, however, also some medical conditions that could cause your stool to be black—such as bleeding somewhere in your digestive tract.

This could be more serious and would require medical attention.

Read on to learn what foods, supplements, and potential  medical conditions cause black stool.

We’ll also discuss how black stool is diagnosed and when you should be calling your doctor.

Why Stool Color Is Important

Your poop is your body’s way of taking out the garbage.

Foods you eat that your body doesn’t need, as well as waste created by the normal functions of your body, are all dumped into your lower digestive system for you to get rid of.

The color of your poop, typically an orange-brown or yellow-brown, reflects the foods you’ve recently eaten, the bile used in digesting, and the overall health of your body.

A dramatic color change is something to note.

If you are experiencing black stool, there are other symptoms to watch for that may indicate you have an underlying medical issue.

We will go over all of these shortly.

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Foods That Cause Your Poop To Be Black

Let’s talk about some of the foods that make your stool black.

Then, we will look at what some of the possible medical conditions are that also cause black stool.

Dark-Colored Foods

As mentioned earlier, before you panic, think back on what you have recently eaten. 

Here are some foods that are known to make your poop dark:

  • Blueberries
  • Black licorice
  • Blood sausage

Beets and foods with a lot of red food coloring can make your poop a dark, sometimes red color as well. 

Iron Supplements 

Iron supplements are sometimes taken to treat anemia that is caused by lower iron levels.

Taking iron can be a great way to build up your iron stores if it’s low, but it can influence your GI tract.

Having black poop is completely normal while taking iron supplements and not something to worry about.

Medicines With Bismuth

Bismuth is a medication that’s been used for over 100 years.

It is FDA-approved to treat diarrhea, nausea, indigestion, and heartburn.

A common side effect of taking medications that contain bismuth is black stool.  

Medications that contain bismuth are:

  • Kaopectate
  • Pepto Bismol
  • Maalox

If you don’t have any other symptoms along with the black stool and your poop is a normal consistency and smell, your black stool is probably just a side effect of your bismuth medication.

Medical Conditions That Cause Your Poop To Be Black

Let’s go over each of the medical conditions that can cause bleeding.

We also listed some accompanying symptoms to watch for with each condition. 

GI Bleeding

Black stool can be a sign that blood is present.

Bleeding that is happening in your upper GI tract or the beginning of your colon will look black in your poop.

It can also have a very foul smell and a tar-like consistency.  

Note: Bleeding that is happening in your lower GI tract will be bright red and not black.

Typically, other symptoms accompany a GI bleed, such as:

  • Feeling weak or lightheaded
  • Pale skin
  • Vomiting blood or coffee-ground material
  • Abdominal pain
  • Shortness of breath

Bleeding in your GI tract could potentially be a medical emergency, depending on how much bleeding is happening.

Let your medical provider know immediately if you suspect a GI bleed and call 911 if you feel like you’ve lost a lot of blood.

Gastritis

Gastritis is when the lining of your stomach becomes inflamed; it can sometimes bleed as a result.

Gastritis is often caused by the bacterium H. pylori but can also be caused by smoking nicotine, drinking alcohol, a virus, and taking non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen.

Other symptoms to watch for:

  • Pain in your upper abdomen
  • Loss of appetite
  • Vomiting blood or coffee-ground like material

Colitis

Colitis is when the colon part of your intestine is inflamed; it’s a type of irritable bowel syndrome.

Sometimes colitis can cause sores to form in your intestines, and those sores can bleed.

Other symptoms to watch for:

  • Abdominal pain
  • Pus and blood in your poop
  • Loss of appetite
  • Weight loss

Esophageal Varices

Your esophagus is the part of your digestive tract that connects your mouth to your stomach.

Sometimes people who have liver problems have enlarged veins in their esophagus, which are called varices.

At times these enlarged veins can rupture and bleed.

Other symptoms to watch for:

  • Tarry stool
  • Feeling lightheaded
  • Pale skin
  • Vomiting blood

Bleeding Ulcer

A bleeding ulcer, also called a peptic ulcer or stomach ulcer, is when there is an open sore in the first part of your small intestines, in the section right after your stomach.

Sometimes bleeding ulcers are caused by the bacterium H. Pylori, but they can also be caused by long-term use of NSAIDs like ibuprofen.

Watch out for abdominal pain that:

  • Starts at night or between meals
  • Stops if you eat or take an antacid
  • Lasts for minutes to hours
  • Comes and goes for a few days or weeks

Mallory-Weiss Tear

A Mallory-Weiss tear is when the connection between the esophagus and the stomach gets a tear in it. This is usually caused by very forceful or long-term coughing or vomiting.

This tear will bleed, and you may vomit blood or have black blood in your poop.

The tear usually repairs itself within a few days, and surgery is usually not needed.   

Esophageal and Gastric Cancers

Tumors (even benign ones) growing in your digestive tract can cause bleeding as they weaken the lining of your digestive tract.

If the tumor that is bleeding is higher up in your digestive tract, the blood could appear black in your stool after it has encountered your digestive enzymes.

Other symptoms to watch for:

Angiodysplasia

Angiodysplasia is when some of the blood vessels in the colon start to break down and bleed due to age.

This is a problem typically only seen in aging adults.

The bleeding in the colon can cause the poop to be black.

Other symptoms to watch for:

  • Weakness
  • Shortness of breath (from being anemic)
  • Pale coloring
  • Fatigue

Colon Polyps

A polyp is an extra overgrowth of tissue in your body.

Colon polyps grow in your colon or large intestine.

Most of them are not dangerous, but they can sometimes cause bleeding and should be checked for cancer.

Depending on where the polyp is, you may see bright red or black in your stool.

Black Stool Diagnosis 

To determine the cause of your black stool, your primary provider will likely start with a physical exam and a review of your health history including all of the medications, vitamins, and supplements you take.

Depending on your symptoms and if bleeding is suspected, you might be sent for some of these lab tests:

CBC (Complete Blood Count) 

This panel will check to see if you’re anemic due to blood loss. 

Fecal Occult Test 

This is a take-home test for your poop.

When you have a bowel movement, you collect a sample of your stool and take it to the lab for testing.

This will reveal if the cause of the black stool is blood or not.

If it is determined that you have a bleed somewhere in your digestive tract, your medical provider will need to determine where the bleed is so it can be correctly treated.

Finding the bleed can be done through multiple procedures.

Endoscopy 

This is when a tiny camera on a scope is fed through your digestive system.

It can be done through your upper GI tract or your lower GI tract (these are called colonoscopies).

This test is done in a hospital or outpatient center with light sedation to help keep you comfortable.

GI Series 

Before your test, you drink a liquid called barium and then an x-ray is done to observe how the liquid passes through your digestive tract.

A GI series requires fasting beforehand and is done in an outpatient or hospital setting.

Exploratory Surgery

Now and then, if the source of the bleeding cannot be determined in other ways, a surgeon may opt to go in and find the cause via surgical methods. 

Treatment Options for Black Stool

Treatment for black stool depends on the underlying cause.

In many cases, you don’t need to do anything at all.

Other times, it may require something as simple as a change in diet or a clip placed where the bleed is.

Your provider will discuss your treatment options with you after they’ve determined the source of your bleeding, if applicable.

Concerned about your stool color? Chat with a provider through K Health.
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When To See a Medical Provider

Seek medical care immediately if you are having black stool and any of the following symptoms:  

  • Feeling faint or passing out
  • Severe pain in your abdomen
  • Vomiting blood or coffee-ground material
  • Passing tarry-textured stool 
  • Losing weight for no discernible reason
  • Feeling short of breath

How K Health Can Help

Did you know you can get affordable primary care with the K Health app?

Download K to check your symptoms, explore conditions and treatments, and, if needed, text a provider in minutes. K Health’s AI-powered app is HIPAA compliant and based on 20 years of clinical data.

K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Alicia Wooldridge, MD

Dr. Alicia Wooldridge is a board certified Family Medicine physician with over a decade of experience.