The truth is, the color of your poop can give you a sense of your overall gut health, so it's worth paying attention to it. And while poop can come in a variety of colors (green and brown are common, experts say), there's one color that usually warrants a checkup with a doctor: black poop. What does black poop mean?
Content What does black stool mean: you changed your dietWhat does black stool mean: you took iron supplementsWhat does black stool mean: you took Pepto-BismolWhat does black stool mean: you have gastrointestinal bleedingThe difference between “melena” and gastrointestinal bleedingOther symptoms that can accompany black stoolThere are many treatment optionsWhen to see a doctor
According to gastroenterologist Samantha Nazareth, black stool can have several causes, from dietary factors to more serious diseases. WomanEL will list them for you.
What does black poop mean: you changed your diet
Are you trying new foods? Dr. Nazareth says that some dark-colored ingredients, like black licorice, blueberries, and black pudding, can affect the color of your poop. Also, red foods (like beets or anything with red food coloring) can turn your poop a dark red color that you might mistake for black.
What does black stool mean: you took iron supplements
If your doctor has prescribed iron pills to treat anemia (a condition that causes low red blood cell counts) or another health problem, black, tarry stools that look almost dark green could be a possible side effect. “The most common benign cause of black stools is taking iron supplements,” says Dr. Nazareth.
In addition to dark stools, iron pills can cause nausea, constipation, or a metallic taste in your mouth. If these side effects bother you, talk to your doctor. He or she may recommend taking a lower dose or switching to a different medication.
What does black poop mean: you took Pepto-Bismol
These over-the-counter medications help relieve symptoms of indigestion, such as nausea, diarrhea, or upset stomach. But bismuth, the active ingredient in Pepto-Bismol, can also interact with small amounts of sulfur in your digestive system and turn your stool black. When bismuth and sulfur mix, they form a substance called bismuth sulfide, which can make your stool darker than normal as it passes out of your body.
Fortunately, this is a harmless side effect. And the color of your stool should return to its normal color a few days after you stop taking the medication.
What does black stool mean: you have gastrointestinal bleeding
Sometimes black stool is a sign of gastrointestinal (GI) bleeding, often caused by a disorder or other medical condition. These include:
- Peptic ulcers: ulcers in the lining of the stomach.
- Gastroesophageal reflux disease (GERD). A chronic form of acid reflux in which stomach contents flow back up into the throat.
- Gastritis: inflammation of the stomach lining.
- Cancer of the stomach, esophagus, or colon.
Because some causes of GI bleeding are serious, your doctor will take this symptom just as seriously. “Black stools can be a medical emergency if they're caused by GI bleeding. Especially if they're accompanied by symptoms like dizziness, weakness, paleness, shortness of breath, or low blood pressure, which could indicate significant blood loss,” says Dr. Nazareth.
If you experience black, tarry stools along with these symptoms, you should seek medical attention immediately, she adds.
The difference between “gastrointestinal” and gastrointestinal bleeding
While you may hear the terms “melena” and gastrointestinal bleeding used interchangeably, they’re not exactly the same thing. “Melena is black, tarry stools that result from digested blood, usually from bleeding in the upper gastrointestinal tract,” says Dr. Nazareth. This includes the esophagus, stomach, small intestine, and sometimes the right side of the colon. As the blood moves through the gastrointestinal tract, it can come out as black stools with a very distinct foul odor that comes from the blood being broken down during digestion.
On the other hand, gastrointestinal bleeding is a broader term that can include both melena (bleeding from the upper gastrointestinal tract) and hematochezia, which is bright red blood that comes from the lower gastrointestinal tract, such as the colon or rectum. Hematochezia is often called “rectal bleeding.” And it looks more like visible blood in the stool than a dark color.
Other symptoms that may accompany black stools
Like many other digestive issues, black stools can be accompanied by other unpleasant symptoms. Often, these symptoms depend on the cause. While you should always consult a doctor and not self-diagnose, here are some other symptoms to look out for, based on the most common causes of black stools.
If it's from iron supplements:
- You may feel pain in your back, groin, muscles, chest, or sides.
- You may feel dizzy or have chills.
- You may experience a metallic taste in your mouth.
- You may feel nauseous or vomit.
- You may have a fever, headache, or redness.
If this happened after taking Pepto-Bismol:
- You may notice that your tongue has also turned black (this is also caused by the active ingredient coming into contact with the sulfur in your saliva).
If it is the result of gastrointestinal bleeding:
- Your stool may have a noticeably sticky consistency or odor – both of which are signs of melena.
- You may feel nauseous and possibly vomit.
- You may have stomach pain.
- You may experience shortness of breath or feel very weak and tired.
- Remember that symptoms of gastrointestinal bleeding require immediate medical attention.
There are many treatment options
Treatment options for black stools vary widely depending on what’s causing them. Sometimes, it’s best to wait and see. If you and your doctor think diet or supplements are to blame, “eliminating the offending substance will help you determine if that’s the cause,” says Dr. Nazareth.
But if your doctor is concerned that your black stools could be a sign of bleeding in your GI tract, they'll likely want to run a few tests to make a diagnosis. These may include blood or imaging tests, as well as an endoscopy, a procedure in which a thin tube with a camera is passed down your esophagus and stomach.
After that, further treatment will depend on the diagnosis. Your medical team will develop a plan to address and stop the bleeding, as well as the source of the bleeding. For example, your doctor may choose to stitch up a wound in your GI tract, or if you have lost a lot of blood, you may need a blood transfusion (a procedure in which you receive donated blood).
When to see a doctor
If you notice that your stool has turned black and you think it's related to recent dietary changes or supplements—like taking Pepto-Bismol or eating an unusual amount of black licorice—you can wait until your bowel movements return to normal in a few days. Although it's still a good idea to let your doctor know what's happening, just in case.
But since black stools can also be a sign of a more serious condition, it's almost always better to err on the side of caution and seek medical attention right away. This is especially true if you also have:
- Abdominal pain (according to Dr. Nazareth, this could be a sign of an ulcer or some types of cancer).
- Nausea or vomiting, especially if you vomit blood or something that looks like coffee grounds.
- Unintentional weight loss.
- Fatigue, dizziness, or lightheadedness.
- A strong, pungent odor along with black stools (according to Dr. Nazareth, this is typical of melena).
- Shortness of breath or rapid heartbeat (i.e. irregular heartbeat).
- Pale skin.
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