Why Does Blood Appear in the Stool?
Reviewed by Semenko Vitaliy Oleksandrovych, Orthopedic Trauma Surgeon updated: 26 February 2026
Why There May Be Blood in the Stool: The Most Common Causes
Blood in the stool is a symptom, not a diagnosis in itself, and the causes can range from relatively harmless to serious. Most often it is related to an anal fissure or hemorrhoids: in the latter case, removal of hemorrhoids may be needed, while a fissure that does not heal with conservative treatment may require anal fissure removal. Other causes include rectal polyps, inflammatory bowel disease, diverticulosis, infections, and, less commonly, tumors.
What Red, Dark, or Black Stool Color Means
| Color or Appearance of Stool | What It May Mean | When Medical Help Is Needed |
|---|---|---|
| Bright red blood on paper or on the surface of the stool | Bleeding source near the anus — fissure, hemorrhoids | If episodes recur or pain increases |
| Blood mixed into the stool | Source further up — colon, polyps, inflammation | A doctor’s visit is always advisable |
| Dark red, maroon stool | Bleeding from the upper intestine | Needs evaluation soon |
| Black, tarry stool (melena) | Bleeding from the stomach or duodenum | Emergency medical care |
Blood in Stool Along with Pain, Diarrhea, Fever, or Weight Loss
A combination of blood with cramping abdominal pain, prolonged diarrhea, fever, or unexplained weight loss may point to inflammatory bowel disease, an intestinal infection, or other conditions requiring detailed evaluation. Such combinations of symptoms should not simply be attributed to hemorrhoids without a doctor’s examination.
When Blood in the Stool Requires Emergency Care
Urgent care is needed for heavy bleeding, black tarry stool, dizziness or weakness, sharp abdominal pain, or blood in the stool accompanied by vomiting blood. These signs can indicate massive gastrointestinal bleeding that requires hospitalization.
How a Doctor Determines the Cause of Blood in the Stool
The workup usually starts with a history, examination, and a digital rectal exam, after which anoscopy, rectosigmoidoscopy, or colonoscopy may be ordered to examine the intestinal lining. If polyps are found, they can often be removed during the procedure itself — removal of rectal polyps — and if a malignant process is suspected, a biopsy and further treatment follow, up to removal of rectal cancer.
What to Do If There Is Blood in Your Stool
If blood appears in the stool, it is best not to delay seeing a doctor, even if the bleeding is minor and painless. Self-treatment can mask the symptoms of a more serious condition. Before the consultation, avoid taking pain relievers on your own, as they can increase bleeding, and pay attention to any accompanying symptoms so you can describe them to the doctor in detail.
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