Blood in stool: causes and when to worry
The short answer
Bright red blood on toilet paper or streaked on stool often comes from hemorrhoids or a small anal tear, while dark red, maroon or black tarry stool points to bleeding further up the gut. A small one-off streak is often minor, but blood that keeps coming back, or comes with a change in bowel habit, weight loss or tiredness, should be checked by a doctor. Heavy bleeding, clots, dizziness or black tarry stool need urgent care.
Seeing blood when you wipe or in the toilet bowl is frightening. Most of the time the cause is small and treatable, usually a hemorrhoid or a tiny tear near the anus. Still, rectal bleeding is one of the symptoms doctors want to hear about, because the same sign can occasionally come from something further up the bowel that is easier to treat when it’s found early.
The color, the amount and what else is going on tell you a lot about where the blood is coming from and how quickly to act. This guide walks through each.
What blood in stool looks like
Blood changes color as it travels through the gut. The further it has come, the darker it gets.
| What you see | Where it’s likely from | Common causes |
|---|---|---|
| Bright red blood on toilet paper, streaks on the outside of stool, pink water | The anus or the last part of the rectum | Hemorrhoids, anal fissure |
| Bright red or dark red blood mixed into stool | The rectum or colon | Hemorrhoids, inflammation, infection, polyps, diverticular bleeding, cancer |
| Maroon stool or dark red clots | The colon or lower small intestine | Diverticular bleeding, inflammation, polyps, cancer |
| Black, sticky, tar-like stool | The stomach or upper small intestine | Stomach ulcer, inflamed stomach lining, bleeding from anticoagulants or NSAIDs |
| Blood you can’t see | Anywhere | Found only by a stool test |
Before you assume it’s blood, think about the last day or two. Beets, red food coloring, tomato juice and red drinks can tint stool red. Iron tablets, bismuth medicines such as Pepto-Bismol, black licorice and blueberries can turn it black. The poop color chart covers those food causes in more detail, and the guide to black stool explains how to tell harmless black stool from bleeding.
Bright red blood in stool
Bright red means the blood is fresh, so it usually comes from close to the exit.
Hemorrhoids are swollen veins in and around the anus. Internal hemorrhoids often bleed without hurting, leaving bright red blood on the paper or dripping into the bowl after you go. External hemorrhoids can itch, feel like a lump and become painful if a clot forms inside one. Straining, constipation, pregnancy and sitting on the toilet for a long time all make them more likely.
An anal fissure is a small tear in the lining of the anus, often caused by passing a hard stool. It usually hurts while you go and for a while afterward, sometimes for hours, and leaves a little bright red blood on the paper. Fissures often follow a bout of constipation.
Other causes of bright red bleeding include anal sex or injury, some sexually transmitted infections, and anticoagulant medicines like warfarin or apixaban, as well as aspirin, which make any bleeding more noticeable.
Painless bright red blood
Painless bleeding is most often from internal hemorrhoids, which is reassuring. Polyps and bowel cancer usually don’t hurt either, so bleeding without pain is no reason to skip a check if it keeps coming back.
Blood only when wiping
A smear on the paper after a hard stool, with nothing in the bowl, is the classic pattern of a fissure or hemorrhoid. If it settles once your stools are softer, that fits. If it keeps happening for more than a few weeks, see a doctor.
Dark red or maroon blood
Darker blood has usually come from higher in the colon, so it has had time to change color. Possible causes include diverticular disease (small pouches in the bowel wall that can bleed), inflammatory bowel disease such as ulcerative colitis or Crohn’s disease, infections that cause bloody diarrhea, polyps and colorectal cancer. Dark red or maroon blood is less likely to be a simple hemorrhoid and should be seen by a doctor promptly.
Blood in stool with clots
A clot forms when there’s enough blood for it to pool and set. Clots, or toilet water that turns red, usually mean more bleeding than a streak on the paper. Large clots or a lot of blood need emergency care. Smaller clots that come once, for example with a flaring hemorrhoid, still deserve a prompt appointment so a doctor can find the source.
Blood with mucus or diarrhea
Blood mixed with slimy mucus, or bloody diarrhea, can come from an infection, inflammatory bowel disease, or sometimes polyps or cancer. A stomach bug can cause it for a few days, but bloody diarrhea should always get medical advice the same day. The mucus in stool guide explains what mucus on its own usually means.
When to see a doctor
A small amount of one-off bleeding that has a clear cause, such as a hard stool you strained to pass, often settles by itself. Make an appointment if:
- you’ve had blood in your stool on and off for three weeks or more
- your stools have been looser, more frequent, thinner or otherwise different for three weeks or more
- you’ve lost weight without trying, or feel unusually tired
- you have pain or a lump in your belly, or a lot of pain around the anus
- you’re around 45 or older, or a close relative had bowel cancer
- you can’t tell whether what you’re seeing is blood
- a child has blood in their stool
Ask for an urgent appointment or same-day advice if:
- your stool is dark red, maroon or black
- you have bloody diarrhea
- you take blood thinners and notice new bleeding
Call emergency services or go to the ER if:
- the bleeding won’t stop, or there’s a lot of blood, such as red toilet water or large clots
- you have black, tarry stool along with dizziness, weakness, a fast heartbeat or fainting
- you’re vomiting blood or something that looks like coffee grounds
- you have severe belly pain
Don’t drive yourself if you feel faint.
A doctor will usually ask about your symptoms, examine the area, possibly with a gloved finger, and may test a stool sample or refer you for a colonoscopy or another look inside the bowel. Bowel cancer is much easier to treat when it’s found early, which is why persistent bleeding is always worth checking even when it turns out to be hemorrhoids.
What helps with hemorrhoids and fissures
Once a doctor has confirmed that hemorrhoids or a fissure are the cause, most of the treatment is about softer, easier stools. Eat more fiber from fruit, vegetables, beans and whole grains, drink enough fluid, and don’t strain or sit on the toilet scrolling your phone. A warm bath can ease pain. A pharmacist can suggest creams or stool softeners. If stools are hard or you go rarely, the guides on constipation relief and how often you should poop are a good next read.
Tracking bleeding for your appointment
Doctors will ask when the bleeding started, how often it happens, what it looked like and whether your bowel habit has changed. That’s hard to answer from memory. A simple record helps: the date, whether there was blood, the color, and the Bristol stool type so you can see whether bleeding follows hard stools.
Poopwell lets you log a bowel movement with one tap and add blood, mucus, pain and color to the entry. When you log blood, or choose a black, red or pale color, the app shows a plain reminder to discuss it with a doctor and a list of signs that need urgent care. Those entries are counted under medical alerts in the PDF report, which you can show at your appointment. The app doesn’t diagnose anything, and it’s no substitute for getting bleeding checked.
Questions people also ask
When should I worry about blood in my stool?
See a doctor if you've had blood in your stool on and off for a few weeks, if it comes with looser or more frequent stools, weight loss you can't explain, tiredness or belly pain, or if you're over about 45 or have a family history of bowel cancer. Get emergency care for heavy bleeding, large clots, black tarry stool, or feeling dizzy or faint.
Is bright red blood in stool serious?
Often it isn't. Bright red blood usually comes from near the anus, and hemorrhoids and anal fissures are the most common causes. It can also come from polyps, inflammation or cancer in the lower bowel, so bleeding that repeats or has no obvious cause should be checked.
What does blood in stool look like?
It depends on where it comes from. Bleeding near the anus looks bright red, on the paper, as streaks on the outside of stool or pink in the toilet water. Bleeding higher in the colon tends to be dark red or maroon and mixed in. Bleeding from the stomach or small intestine usually turns stool black and tar-like.
Is painless bright red blood in stool a bad sign?
Painless bright red bleeding is often from internal hemorrhoids, which usually don't hurt. It can also come from polyps or bowel cancer, which are often painless too, so the lack of pain doesn't rule anything out. If it keeps happening, see a doctor.
What does blood in stool with clots mean?
Clots usually mean a larger amount of bleeding. Large clots, or toilet water that turns red, need emergency care. Small clots that come once with a hemorrhoid flare still need a doctor to look at them, sooner rather than later.
Sources
This guide is general information, not medical advice. If you're worried about a change in your bowel habits, talk to a doctor. Get urgent help for heavy bleeding, black tarry stool with dizziness, or severe belly pain.
