Get emergency care if you pass a lot of blood, or you have blood in stool together with dizziness, fainting, a racing heart, severe belly pain or vomiting blood. Call your local emergency number.
Short answer
Bright red blood on toilet paper or the surface of stool most often comes from hemorrhoids or a small tear near the anus. Maroon or dark red blood mixed through stool suggests bleeding higher in the colon. Black, tarry stool suggests bleeding in the stomach or upper gut. Any blood that keeps happening, or that you cannot explain, should be checked by a clinician.
What does blood in stool look like?
Blood in stool can look bright red, maroon or dark red, or black and tarry, depending on where in the gut it comes from. Sometimes it is not visible at all.
| What you see | Where it may come from | Common causes |
|---|---|---|
| Bright red blood on paper, or streaks on the stool | Rectum or anus, the lowest part of the gut | Hemorrhoids, anal fissures |
| Maroon or dark red blood mixed in | Colon or lower small intestine | Diverticular disease, inflammatory bowel disease, infection, polyps |
| Black, tarry, sticky stool | Stomach or upper gut | Ulcers, gastritis, esophageal varices |
| No visible blood (occult blood) | Anywhere in the gut | Found on a stool test. Polyps, ulcers, colorectal cancer, among others |
What causes blood in stool?
The most common cause of bright red blood in stool is hemorrhoids, but blood can also come from anal fissures, diverticular disease, inflammatory bowel disease, infections, ulcers, polyps or colorectal cancer.
- Hemorrhoids. Swollen veins around the anus. They cause bright red blood, often painless, seen on paper or in the toilet.
- Anal fissures. Small tears in the skin, often from hard stool. They cause sharp pain during and after a bowel movement, and a little bright red blood.
- Diverticular disease. Small pouches in the colon wall can bleed suddenly, often painlessly, with maroon or red blood.
- Inflammatory bowel disease. Crohn's disease and ulcerative colitis cause bloody diarrhea, often with mucus, cramps and weight loss.
- Infections. Some bacterial infections cause bloody diarrhea with fever.
- Ulcers and gastritis. These bleed into the upper gut and give black, tarry stool.
- Polyps and colorectal cancer. These can bleed slowly, sometimes without any visible blood at first.
Which foods and medicines can look like blood in stool?
Beets, tomato juice and soup, red gelatin, red drink mixes and red food dye can turn stool red. See red stool for how to tell the difference. Iron and bismuth (Pepto-Bismol) can turn stool black. If you ate one of these, the color should clear within a couple of days. If you are not sure, treat it as possible blood and get advice. Do not guess when the color is dark, sticky or repeated.
When is blood in stool an emergency?
Blood in stool is an emergency if you pass a large amount of blood or clots, have black tarry stool, or feel dizzy, faint or weak. Any new or repeated blood in stool should be checked by a doctor.
Call a doctor within a day
- Any blood in stool that is new, repeated or unexplained
- Small streaks of bright red blood that keep coming back
- Blood together with a change in bowel habits, weight loss or tiredness
- You are 45 or older and have never been screened for colorectal cancer
Get care now
- A large amount of red or maroon blood, or blood clots
- Black, sticky, tar-like stool
- Dizziness, fainting, a racing heart or very pale skin
- Severe belly pain, or vomiting blood
- Bloody stool with a high fever
In the United States, current guidelines generally suggest colorectal cancer screening from age 45 for people at average risk. Ask your doctor what is right for you. Blood in stool is not a substitute for screening, and absence of blood does not rule out a problem.
Warning signs to know
These are signs that published medical guidance says need prompt or urgent care. The list is not complete, and ticking boxes cannot tell you whether you are ill. If you are worried, contact a clinician whatever you tick.
Questions people ask
Is a little blood in stool normal?
A small amount of bright red blood on toilet paper is common and often caused by hemorrhoids or a small tear. It still should not be assumed harmless if it keeps happening, so mention it to a clinician.
What does blood in stool look like?
It can be bright red on the paper or the stool surface, maroon or dark red mixed in, or black and tarry. Sometimes it is not visible at all.
When should I worry about blood in stool?
Worry if you pass a lot of blood, if stool is black and tarry, or if you feel dizzy, faint, weak or have severe belly pain. Also see a doctor if bleeding repeats or comes with weight loss or a change in bowel habits.
Can hemorrhoids cause blood in stool?
Yes. Hemorrhoids are the most common cause of bright red blood on toilet paper or on the surface of stool. They are usually painless. Other causes can look similar, so get new or persistent bleeding checked.
What causes blood clots in stool?
Clots suggest heavier bleeding. Causes include diverticular bleeding, inflammatory bowel disease, and other conditions in the colon. Seek medical care promptly.
Sources
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