Blood in your stool can look bright red, dark maroon, or jet black depending on where the bleeding originates in your digestive tract. It doesn’t always look the way you’d expect. Sometimes it’s obvious, like red streaks on toilet paper. Other times, the only sign is a stool that looks unusually dark or sticky.
Bright Red Blood
Bright red blood typically comes from the lower part of your digestive tract, meaning the colon, rectum, or anus. This is the most recognizable form. You might notice it as red streaks on the outside of your stool, drops in the toilet bowl, or a small amount on the toilet paper after wiping. The blood looks red because it hasn’t traveled far or been exposed to digestive chemicals, so it still resembles the blood you’d see from a cut on your skin.
The most common causes of this kind of bleeding are hemorrhoids and anal fissures (small tears in the lining of the anus). In these cases, the blood is usually a small amount, separate from the stool itself, and bright enough to be unmistakable. Larger amounts of bright red blood, or blood that’s clearly mixed into the stool rather than sitting on the surface, can point to something deeper in the colon, like polyps, diverticular disease, or inflammatory bowel disease.
Dark Red or Maroon Stool
When bleeding happens higher up in the colon or in the small intestine, the blood has more time to break down before it exits. This gives the stool a dark red or maroon color, and the blood tends to be mixed throughout rather than visible on the surface. The texture of the stool may also change, appearing looser or more clumpy than usual. This type of bleeding is less common than the bright red variety and generally signals a source that’s farther from the rectum.
Black, Tarry Stool (Melena)
Bleeding from the upper digestive tract, such as the stomach or esophagus, produces stool that looks completely different from what most people picture. Classic melena is jet black with a tarry, sticky consistency. It happens because stomach acid chemically transforms the red pigment in blood into a dark brown or black compound as it passes through the digestive system. The stool often has a distinctly foul smell that’s noticeably different from normal.
A small amount of upper GI bleeding may produce stool that looks more dark brown than truly black, which can make it harder to recognize. If the bleeding is significant, the stool becomes unmistakably black, shiny, and tar-like. This appearance is a reliable signal that the bleeding source is in the stomach or upper small intestine rather than the colon.
Invisible Blood (Occult Bleeding)
Sometimes blood in the stool isn’t visible at all. The stool looks completely normal to the naked eye, but a lab test can detect tiny traces of blood. This is called occult (hidden) bleeding, and it’s one reason routine screening tests exist. A fecal immunochemical test, or FIT, uses antibodies to detect a blood protein in your stool sample. It’s better at catching cancer and precancerous polyps than older testing methods and produces fewer false positives. Occult bleeding is particularly relevant for colorectal cancer, which can bleed into the digestive tract intermittently without producing any visible change in stool color or consistency.
Foods and Medications That Mimic Blood
Before assuming the worst, consider what you’ve eaten or taken recently. Beets, tomatoes, and foods with red food coloring can turn stool reddish in a way that looks alarmingly like blood. On the darker end, blueberries, black licorice, blood sausage, iron supplements, bismuth (the active ingredient in Pepto-Bismol), and activated charcoal can all produce dark or black stools that mimic melena. The key difference is texture: stool darkened by food or medication is typically firm and normal in consistency, while true melena is sticky and tar-like.
What Blood in Stool Looks Like With Specific Conditions
Hemorrhoids and Fissures
Small amounts of bright red blood on toilet paper or dripping into the bowl. The stool itself usually looks normal. The blood is on the surface, not mixed in. You may also notice pain or itching around the anus, particularly with fissures.
Colorectal Cancer
Blood from a colorectal tumor can be bright red or dark enough to make the stool look dark brown or black, depending on the tumor’s location. Often, the bleeding is so subtle that the stool looks entirely normal. Other signs include a change in bowel habits lasting more than a few days, such as new constipation, diarrhea, or stools that are noticeably narrower than before. Many of these symptoms overlap with far more common and benign conditions.
Ulcerative Colitis
Bloody diarrhea is a hallmark. The blood is typically bright red to dark red, mixed into loose or watery stool, and often accompanied by mucus, urgency, and cramping. Crohn’s disease, the other main form of inflammatory bowel disease, usually does not cause visibly bloody stool.
Stomach Ulcers
Bleeding from a stomach ulcer typically shows up as black, tarry stool. If the bleeding is rapid and severe, vomit may appear dark brown and granular, often described as looking like coffee grounds. That color comes from stomach acid chemically altering the blood before it’s expelled.
Blood in Children’s Stool
Seeing blood in a child’s diaper or stool is understandably alarming, but the causes in children are often different from those in adults. Anal fissures are the most common culprit, particularly in toddlers dealing with constipation. Infants may develop blood-streaked stools from a milk protein allergy, which triggers inflammation in the lining of the colon. Older children and adolescents can develop juvenile polyps or, less commonly, inflammatory bowel disease. Severe bleeding requiring hospitalization occurs in only about 5 to 10 percent of pediatric cases.
Signs That Bleeding Is Serious
A small amount of bright red blood on toilet paper after a hard bowel movement is common and usually not dangerous. But certain patterns demand urgent attention. If the amount of blood suddenly increases, if you’re passing large clots, or if the bleeding doesn’t stop, that points to something more significant. Symptoms that appear alongside the bleeding are just as important: abdominal cramping, dizziness or lightheadedness, feeling unusually tired, or shortness of breath all suggest you’re losing enough blood to affect your body’s ability to function.
The most dangerous scenario is shock from rapid blood loss. Signs include confusion, a racing heartbeat, pale skin, cold hands and feet, and heavy sweating. This is a life-threatening emergency. Black, tarry stools that persist over multiple bowel movements also warrant prompt medical evaluation, since they indicate ongoing bleeding from the upper digestive tract.