Why Do I Have Red or Black Blood in My Poop?

Foods, medication, and blood from the GI tract can cause stool to be dark

If your poop seems to have red or black blood in it, it could be a sign of a medical problem. It's also possible the color could be due to something you ate.

Foods with artificial colors are a common culprit. Certain supplements, like iron, may also cause discolored stools.

Red or black stools could be caused by bleeding in the gastrointestinal (GI) tract. In some instances, it may be an indication of a serious condition like colon cancer. However, it is more likely to be related to easily treated problems like hemorrhoids.

This article discusses some of the reasons for red or black stools, and how to know the difference between dietary causes and those that need to be evaluated by a doctor.

Black vs. Red Stool Medical Causes

Verywell / Jessica Olah

What Is Blood in Stool?

Blood in the stool occurs when you have bleeding along the gastrointestinal tract. If blood looks red, the bleeding is lower in the digestive tract, such as in the colon or rectum. If the blood is black, it's a sign that the bleeding is further up the GI tract, such as in the stomach or small intestine.

Causes of Black Blood in Stool

Black, tar-like stool caused by GI bleeding is called melena. True melena is not only black but foul-smelling as well. There can also be false melena, which looks like blood in the stool but is actually from something you ate.

If you have melena, your doctor may order a fecal occult blood test. This will help determine how much blood is in your stool.

The following conditions affect the upper GI tract so they may cause black blood in the stool.

Bleeding Ulcer

An ulcer is a sore anywhere along the lining of the stomach or intestine. Ulcers can sometimes bleed.

Ulcers usually have one of two causes:

Gastritis

Gastritis is an inflammation of the stomach lining. It can have various causes, including:

  • Overindulging in alcohol or food
  • Eating spicy foods
  • Smoking
  • Infection with bacteria
  • Prolonged use of NSAIDs

Certain medical conditions can also lead to gastritis. These include:

Bleeding in the Esophagus

A few medical conditions can cause bleeding in the esophagus. These include:

Gastric Cancer

Stomach (gastric) cancer can cause tarry black stools along with symptoms like weight loss, vomiting, abdominal pain, and difficulty swallowing. While it isn't clear what causes gastric cancer, some of the risk factors include:

  • Diets high in salted or smoked foods and processed meat
  • Infection with Helicobacter pylori
  • Drinking alcohol
  • Smoking

Causes of Red Blood in the Stool

Red- or maroon-colored stool that contains blood is called hematochezia. The brighter color is because the blood is coming from lower in the digestive tract, like the colon or the rectum.

Red blood in the stool can have a number of medical causes. Always see your healthcare provider if you find blood in your stool. It is important to find the cause of the bleeding.

Hemorrhoids

Hemorrhoids are a common source of bright red blood in the stool or on toilet paper. These are enlarged veins in the rectal area that may burst and bleed.

Hemorrhoids are not usually serious. They can often be treated with over-the-counter medications. Hemorrhoids that won't heal may need to be seen by a doctor. Prescription medication can help.

Anal Fissure

An anal fissure is a tear or ulcer in the lining of the anal canal. The anal canal is the last part of the rectum before the anus.

Anyone can get fissures, but they are most common in middle-aged people and young adults.

Fissures can cause bright red bleeding. They usually heal with home care.

Colon Polyps and Colon Cancer

Colon polyps can also cause red blood in the stool. Polyps are growths on the inside of the colon. Sometimes they can turn into colon cancer. Colon cancer may also cause blood in the stool.

Blood from these sources is not always visible in or on the stool. Blood that isn't visible is called occult blood.

A fecal occult blood test looks for this kind of blood. This test may be done to screen for colon cancer.

Digestive Disorders

Inflammatory bowel disease (IBD) is a set of conditions that cause inflammation of the bowel. These conditions can cause bleeding in the digestive tract. Both Crohn's disease of the colon and ulcerative colitis can cause bloody stool, often with diarrhea.

Diverticular disease can also cause red blood in the stool. Diverticula are pouches that form in the wall of the colon. People with this condition may have large amounts of blood in the stool.

Other Causes of Discolored Stools

Foods are a frequent cause of discolored stools. This is especially true for foods that contain artificial colors. If your discolored stools are caused by something you ate, the color should go back to normal once the food has been digested and is out of your body.

Some of the things that can cause false melena, or black stools, include:

  • Food
  • Supplements
  • Medications
  • Minerals

Some foods with natural or artificial coloring may cause red stools. These include:

  • Red gelatin, popsicles, or Kool-Aid
  • Tomato juice or soup
  • Large amounts of beets

Red stools in babies may be caused by the popular antibiotic Omnicef, which is often used for ear infections. However, because being on antibiotics can cause an infection of the intestinal tract called C. difficile, always call your healthcare provider if your baby has red stools.

When to See a Healthcare Provider

Blood in the stool may not always be serious. Still, it is important to have this symptom checked out by a healthcare provider.

This is true even when you already have a diagnosis of IBD or another chronic illness. Blood in the stool may mean your treatment needs to be changed.

See a healthcare provider if:

  • You have changes in color, odor, or frequency of stools.
  • You can't think of any food or supplements that could explain the color change.
  • The color change lasts a few days.
  • You have other symptoms, like diarrhea, constipation, weakness, or dizziness.

If you have obvious blood in the stool or are passing blood with no stool, see a healthcare provider at once. If there is extreme pain and blood loss, go to the emergency room or call 911.

Summary

Red or black stools could be caused by something harmless, like food or a supplement. Sometimes, though, it can be caused by bleeding somewhere in your GI tract.

Stomach problems like ulcers and gastritis may cause black stools. Bleeding in the esophagus can also cause this.

Red blood in stool is caused by bleeding lower in the GI tract. Hemorrhoids and anal fissures can cause it. More serious causes can include colon polyps, colon cancer, and digestive disorders like inflammatory bowel disease and diverticular disease.

Always see a healthcare provider if you notice blood in your stool.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.