Why Is My Poop Black? Causes & When It’s Serious

Key takeaways:

• Black poop can be due to things like eating certain foods or can be from a more serious condition, such as gastrointestinal bleeding.
• If you have frequent black poop or black tarry-looking stools, you should get medical attention to rule out any major problems.
• If in addition to black poop, you also have other symptoms such as stomach pain, dizziness, or vomiting, you should get medical attention immediately.

Noticing black poop can be alarming, as black stools may be related to something as simple as your diet or taking certain supplements, or could be the result of a more serious health problem.

Let’s look at the common causes of black poop, help you understand when black poop might indicate a problem, and then explore potential treatment and prevention strategies.

Is black poop normal?

Black poop can be normal if it’s caused by something like foods you have eaten or is the result of taking certain medications or supplements. Knowing what causes black poop and recognizing when it could mean a serious health problem is essential.

For instance, having your poop turn temporarily black due to your diet is almost always harmless, but seeing black, tarry stools can sometimes mean there is bleeding somewhere in your digestive tract. If you suspect gastrointestinal bleeding, this always requires a prompt evaluation by your physician.

Causes of black poop

Black stool can stem from various causes, ranging from dietary choices to more serious medical conditions. Here’s a closer look at some common causes and when they may signal a need for medical attention.

Dietary causes

Certain foods, especially those that are rich in iron or have pigments that give them a very dark color, can cause the appearance of black poop. For example:

• Black licorice, blueberries, and beets all contain dark pigments that may affect your stool color and cause black poop.
• Red meat and liver are both high in iron, which can lead to black poop.
• Dark leafy greens such as kale, collards, and turnip greens are another source of iron and may also cause black poop.

These changes to your stool color are typically harmless, and the color of your poop should go back to normal within a few days after you stop eating these foods.

Iron supplements and multivitamins

Iron supplements are a common cause of dark or black poop, as your body doesn’t absorb all the iron. This unabsorbed iron can darken your stool. This is a well-known side effect of taking iron-containing supplements and is generally not a cause for concern. Some multivitamins also contain iron or other minerals that can have this effect.

However, if your black poop continues even after you have discontinued the iron-containing supplements, or you are experiencing other symptoms such as abdominal pain, diarrhea, or vomiting, you should consult your healthcare provider.

Medications

Certain medications, particularly those containing bismuth, like Pepto Bismol, can turn your poop black. Bismuth reacts with very small amounts of sulfur in your saliva as well as your gastrointestinal tract and creates bismuth sulfide, a black substance that colors your poop.

This effect is temporary and should rapidly fade and stop completely once the medication is discontinued. If the black poop continues after you stop taking the medication, you should consult with your healthcare provider.

Internal bleeding

A more serious cause of black poop is bleeding within your upper gastrointestinal tract, which includes your stomach, esophagus (food tube), and small intestine.

This type of bleeding is known as melena and results in black-appearing, tarry poop with a distinct, very foul odor. Melena is caused by blood that mixes with your digestive enzymes, and this partially digested blood travels through your intestines, darkening the color and also affecting its consistency.

Common causes of gastrointestinal bleeding include:

• Stomach ulcers: These are also called peptic ulcers. It’s now known that most ulcers are caused by an infection from the H. pylori bacteria. Some ulcers can result from the chronic use of non-steroidal anti-inflammatory drugs (NSAIDs) such as brand names Advil, Aleve, and Motrin, among others.
• Esophageal varices: These are swollen varicose veins in the esophagus that can bleed into the esophagus. They are commonly associated with liver disease.
• Gastritis: This is an inflammation of your stomach lining and can be due to alcohol use, infection, or prolonged use of NSAIDs.

All of these causes of gastrointestinal bleeding need to be promptly seen and managed by a physician, as if untreated, can lead to severe complications.

What black poop may mean based on appearance, consistency, or other symptoms

Different types of black stool can indicate various health issues, especially when paired with specific symptoms. Here’s what certain appearances and consistencies of black poop might mean.

• Watery or liquid black poop: This suggests bleeding in your upper gastrointestinal tract (esophagus, stomach, or upper part of small intestine) especially if you also have dizziness or fatigue. Liquid black poop can lead to dehydration, so you should get medical advice promptly if this is occurring.
• Stringy black poop: This type of poop may mean you have mucus and blood in your stool. The presence of mucus usually means there is a condition present that is causing inflammation, such as Crohn’s disease. If you regularly experience stringy black poop you should see your physician for an evaluation as soon as possible.
• Tarry or sticky black poop: Black tarry or sticky black poop is often the result of digested blood coming from bleeding in your GI tract. The presence of blood in your poop is usually also accompanied by a strong, very foul odor. This is very concerning and you should get an immediate medical evaluation.
• Hard black poop: The use of iron-containing supplements can lead to dark, hard poop. In addition to the iron causing the black discoloration, iron can also cause constipation leading to hard poop. Increasing your fluid and fiber intake may help to relieve the constipation caused by iron-containing supplements. If you can’t relieve your constipation with fluids and extra fiber, you should get the advice of your physician.
• Black poop with blood: Visible blood with black poop means active bleeding somewhere in your GI tract. If you see blood, you should get immediate medical attention.
• Black flecks in poop: While this is better than seeing completely black poop, these black flecks could still be due to particles of digested blood coming from somewhere within your digestive tract. Black flecks in poop could also be caused by certain foods or medications. If you see black flecks in your stool, you should be evaluated by your physician to determine the source.
• Black poop and stomach pain: This combination could mean a bleeding stomach ulcer or other gastrointestinal issue. If you have black poop and stomach pain you should get medical attention immediately.
• Black poop after drinking alcohol: Alcohol is a well-known stomach irritant and can cause gastritis, an irritation of the lining of your stomach. Untreated gastritis can in some cases lead to bleeding, especially in individuals with existing liver issues. You should limit or stop drinking alcohol while getting the advice of your physician as soon as possible.
• Black poop while pregnant: If you are pregnant, you may be taking prenatal vitamins containing iron, which can cause black poop. If you have black poop and you are not taking iron supplements or prenatal vitamins that contain iron, or you are having stomach pain, vomiting, or other symptoms, you should see your physician.

Read our guides on different types of stool and stool colors for more.

When to see a doctor about black poop

While black stool is often harmless, certain symptoms alongside it may indicate a more serious underlying issue. Here’s when it’s important to seek medical attention.

You should see your physician if black poop goes on beyond a few days or if you also have symptoms like:

• You experience black poop for 3 days or longer.
• You have persistent or severe abdominal pain.
• You experience unexplained weight loss.
• You feel nauseous or are vomiting.
• You feel dizzy or are fainting.

You should go to the emergency room if:

• You are vomiting blood, which may often resemble coffee grounds.
• You experience severe abdominal pain.
• You are showing symptoms of shock, such as confusion, dizziness, cold sweats, or a rapid heartbeat.

These symptoms suggest that you may have significant blood loss or other serious medical conditions.

Questions to ask your doctor about black poop

If you’re concerned about black stool, here are some questions you can ask your doctor to better understand the cause and steps to take.

• Could my diet or any supplements I’m taking be causing black poop?
• Do you recommend I get any special tests to rule out bleeding in my digestive system?
• What signs should I watch for that could indicate I need emergency care?
• Are there preventive measures, dietary, or lifestyle changes that can help me avoid this issue?

How to stop or treat black poop

Addressing black stool often involves simple dietary changes or medication adjustments, though medical treatment may be necessary for more serious causes. Here are some steps that can help.

Adjust your diet

Reducing your intake of foods that may be causing dark poop, such as iron-rich liver and red meat can help if your diet is responsible.

Also eliminating black licorice, dark green leafy vegetables, or fruits with dark pigments such as blueberries and beets can help you to identify the cause. Drinking plenty of fluids so you stay well hydrated will also support healthy digestion as well as stool consistency.

Review medications and supplements

If your black poop is being caused by taking iron supplements or medications, you can discuss alternatives to these with your physician.

It’s possible your healthcare provider can prescribe a lower dose of medication or switch you to a different supplement.

Get medical treatment

If gastrointestinal bleeding or other underlying health problems are causing you to have black poop, treatment may include medications to reduce your stomach acid, antibiotics for infections, or even surgery to stop bleeding if necessary. Your healthcare provider will guide the appropriate treatment for your condition.

How to prevent black poop

Taking preventive steps can often help you avoid issues with black stool before they start. Here are some ways to maintain digestive health and prevent black stool.

Maintain a balanced diet

Making sure to eat a well-balanced diet with plenty of lean protein, vegetables, and fruit can help support healthy stool color as well as consistency.

If your diet is the reason you are having black poop, avoiding eating large amounts of iron-rich foods and staying well hydrated should prevent this.

Routine check-ups

Annual check-ups and discussing any new symptoms with your healthcare provider can help you to identify any gastrointestinal issues early so you can get treatment if needed.

Regular check-ups are particularly important if you have a history of any gastrointestinal conditions such as irritable bowel syndrome (IBS) or Crohn’s disease.

Frequently asked questions: black poop

Black stool can raise many questions, especially about common causes and remedies. Here are answers to some frequently asked questions to help clarify what may be causing black poop and when it’s normal or concerning.

Can dehydration cause black poop?

While dehydration alone doesn’t typically cause black poop, it can contribute to constipation, which makes your poop appear darker. Getting plenty of fluids will also help to support regular digestion.

Does Pepto Bismol make your poop turn black?

Yes, Pepto Bismol can make your poop turn black. It contains bismuth, which can react with the sulfur found naturally in your saliva as well as in your intestines and temporarily turn poop black.

This effect is harmless and should completely go away once you stop taking Pepto Bismol.

Do iron supplements make your poop turn black?

Yes, iron supplements can frequently cause black poop. This is a common side effect and is harmless. If you are having other symptoms along with black poop such as stomach pain or vomiting, you should see your healthcare provider.

Managing black poop

While black poop can be caused by your diet, some medications, and certain supplements, it’s important to know how to recognize when this might mean a more serious health problem. If your black poop continues or you are having other symptoms such as stomach pain or vomiting, you should see your health provider for an evaluation.

General Medicine follows a strict editorial process, including using real experts to write our articles, vetted primary sources, fact-checking, a secondary medical review, and updates as necessary. This article was medically reviewed and fact checked by Dr. Pallabi Sanyal-Dey, MD.

Sources

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Centers for Disease Control and Prevention. “About Alcohol Use.” Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, https://www.cdc.gov/alcohol/about-alcohol-use/index.html. Accessed 28 Oct. 2024.

Veterans Health Administration. “Gastrointestinal Bleeding: Symptoms, Diagnosis, and Treatment.” Veterans Health Library, U.S. Department of Veterans Affairs, https://www.veteranshealthlibrary.va.gov/Encyclopedia/3,40442. Accessed 28 Oct. 2024.

National Institute of Diabetes and Digestive and Kidney Diseases. “Gastrointestinal Bleeding.” National Institute of Diabetes and Digestive and Kidney Diseases, U.S. Department of Health and Human Services, https://www.niddk.nih.gov/health-information/digestive-diseases/gastrointestinal-bleeding. Accessed 28 Oct. 2024.

"Crohn's Disease." Crohn's & Colitis Foundation, https://www.crohnscolitisfoundation.org/patientsandcaregivers/what-is-crohns-disease. Accessed 28 Oct. 2024.