What is blood in the stool?

It is important to recognize the signs of blood in the stool early. Stool that is bright red, maroon colored, or black may be a sign of rectal bleeding. Several conditions can cause rectal bleeding, such as hemorrhoids, colon cancer, and polyps.
Not all red or black stool indicates the presence of blood. Certain foods can affect the color of your stool. Tomatoes, beets, and cranberries can all make stool look red, as can red food dye. Blueberries, black licorice, and dark leafy vegetables can all turn stool black.
Many causes of rectal bleeding will either resolve on their own or can be treated by a doctor.
Signs and symptoms of bloody stool
Pay attention to the color of your stool and whether it is mixed into the stool or covering it. This may be important information that helps your doctor make a diagnosis.
All of the following may indicate rectal bleeding:
- Dark blood in the stool
- Bright-red blood mixed with or covering the stool
- Black or tarry (resembling the color of tar) stool
- Bright-red bloody vomit
- Vomit that resembles coffee grounds
Bright-red stool may indicate that blood is coming from the rectum or lower digestive tract. Darker blood may suggest that it is coming from the upper digestive tract.
Abdominal cramps may indicate that blood in the stool is also irritating the stomach.
Causes of blood in the stool
Many things can cause blood in the stool. Common causes of rectal bleeding include:
Hemorrhoids
Hemorrhoids are swollen blood vessels in the anus or rectum. They are the most common cause of rectal bleeding and are often related to constipation, pregnancy, heavy lifting, obesity, and diarrhea. They typically do not produce pain.
Anal fissures
Anal fissures are tears in the lining of the anus. They can result from constipation, diarrhea, or inflammation. They frequently cause pain during and after bowel movements.
Proctitis
Proctitis is the inflammation of the rectum’s lining. It may be caused by an infection, radiation therapy, some medications, or inflammatory bowel disease.
Colon polyps
Polyps are growths in the lining of the large bowel. Most do not cause symptoms. However, they may turn into colon cancer if left untreated.
Colon cancer
It is important to catch colon cancer early when it can still be treated. It may or may not produce rectal bleeding. Other symptoms of colon cancer include.
- Abdominal cramping
- Weakness
- Fatigue
- Unintended weight loss
Additional Blood in Stool Causes
Several other disorders may cause rectal bleeding, including:
- Peptic ulcers (sores in the lining of the esophagus)
- Crohn’s disease (chronic inflammation of the gastrointestinal tract)
- Ulcerative colitis (inflammation of the large intestine)
- Gastritis (inflammation of the stomach lining)
- Diverticulitis (inflammation or infection of small pouches in your intestines)
- Intestinal infection

SLIDESHOW
Inflammatory Bowel Disease (IBD) Causes, Symptoms, Treatment See SlideshowWhen to see the doctor for blood in the stool
Continuous rectal bleeding, large quantities of blood in the stool, or black or tarry stool can all be symptoms of serious diseases. In addition, the presence of a fever or excessive weakness combined with bloody stool requires a visit to the doctor.
Diagnosing blood in the stool
A doctor will need to locate which area of the gastrointestinal tract is causing the bleeding. In order to diagnose the cause of blood in the stool, your doctor may perform one or more of the following tests:
- Blood test
- Stool sample
- Colonoscopy, where a camera is inserted into the colon
- Endoscopy, where a camera is inserted through the mouth or rectum
- Capsule endoscopy, where a camera is swallowed
Treatments for blood in the stool
While some causes of blood in the stool may resolve on their own, your doctor may decide on an active treatment to stop the bleeding.
The most common method of treatment is endoscopy. In addition to being a diagnostic tool, it can be used to introduce a needle to inject chemicals or a cauterization device, which is used to burn a part of the body to close it or remove it.
Medication can also be used to control the recurrence of bleeding. Surgery may also be required to remove hemorrhoids or polyps.
What does green stool mean? Stool color chart
The normal color of the stool is brown, although green or greenish stool is also considered normal. The most common causes of green stool include
- Eating green veggies such as spinach and kale
- Ingesting green food coloring
- Taking iron supplements
Sometimes during diarrhea when the food moves through the intestine rapidly, there isn’t enough time for the bile to break down the food completely. This may also cause green stools.
Stool color chart
Color | Potential Cause | What to Do |
Black | Gastrointestinal (GI) bleeding | It's an emergency |
Black | Iron, bismuth | Cannot assume this to be the reason for the stool color |
Maroon | GI bleeding | This is an emergency |
Red | Hemorrhoids | Consult a physician |
Red | Inflammatory bowel disease | Consult a physician |
Red | Infection, diverticular bleed | Consult a physician |
Red | Tumor, rapid upper GI bleeding | Consult a physician |
Green | A diet high in green vegetables | Consult a physician |
Green | Associated with diarrhea | Consult a physician |
Green | Normal color | Consult a physician |
Brown | Normal color | Nothing |
Yellow | Diseases of the pancreas | Consult a physician |
Yellow | Celiac disease, cystic fibrosis | Consult a physician |
Yellow | Giardia infection | Consult a physician |
Clay, pale yellow or white | Liver or biliary disease | Lack of bile in the stool |
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Which foods can change the color of stools?
Foods can play a major role in changing the color of stools, which include
- Green leafy vegetables such as spinach and kale (green)
- Green food coloring used in drinks or ice pops (green)
- Iron supplements (green or black)
- Gluten-rich foods such as wheat, barley or rye (yellow)
- Bread, pasta and cookies (yellow)
- Barium (black)
- Black licorice (black)
- Blueberries (black)
- Beets (red)
- Tomato soup (red)
- Gelatin dessert (red or orange)
- Red drinks (red)
- Carrots (orange)
- Winter squash (orange)
- Pumpkin (orange)
- Sweet potatoes (orange)
- Sodas (orange)
- Candy (orange)
What causes a color change in the stools?
Some common causes of color change in the stools include
- Bleeding in the stomach (tar-colored stools)
- Bleeding in the lower parts of the intestines or colon (maroon-colored stools)
- Bismuth-containing medications (black stools)
- Tumor (red-colored stools)
- Piles (bright red blood in stools)
- Aluminum hydroxide containing antacids or antibiotics (yellowish-white stools)
- Iron pills (black stools)
- Pancreatic cancer (bright yellow stools)
- High fat foods (bright yellow stools)
- Weight loss medications
- Pancreatitis (inflammation of the pancreas)
- Diarrhea (green stools)
- Celiac disease (gluten intolerance)
- Cystic fibrosis (inherited life-threatening condition that damages the lungs and digestive system)
What are the symptoms associated with stool color changes?
Symptoms associated with the stool color may be due to an underlying condition. In many cases, there may be no symptoms at all. Accompanying symptoms include the following
- Weakness or dizziness due to loss of blood from the body
- Nausea, vomiting of blood, diarrhea and cramping due to the presence of blood in the stomach
- Abdominal pain due to the underlying cause of the bleeding, for example, an ulcer
- Weight loss due to cancers
- Gas
- Foul-smelling stools
- Loose stools
When should I seek medical care for stool color changes?
If the stool color changes are due to changes in the diet, it will resolve on its own. If there’s a persistent change in the color of the stool, you should seek immediate medical attention.
Additionally, contact a physician if you observe the following symptoms
- Vomiting
- Diarrhea
- Fever
- Abdominal pain
Health Solutions From Our Sponsors
American Society for Gastrointestinal Endoscopy: "Understanding Minor Rectal Bleeding."
John Hopkins Medicine: "Health: Gastrointestinal Bleeding or Blood in the Stool."
University of Iowa Hospitals & Clinics: "Stools with blood."
Medscape Medical Reference
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