Bloody diarrhea can range from bright red streaks on loose stool to watery bowel movements that are entirely red, maroon, or even black. The color and pattern of the blood tell you a lot about where the bleeding is coming from and how serious it might be. Here’s what to look for and what different appearances mean.
Bright Red Blood
The most recognizable form of bloody diarrhea involves bright red blood, either mixed into watery stool or coating the surface. This color indicates the bleeding source is in the lower digestive tract, typically the colon or rectum. The blood looks red because it hasn’t traveled far enough through the gut to be broken down by digestive enzymes.
You might see this as red-tinged water in the toilet bowl, streaks of red on the stool itself, or stool that’s uniformly pinkish-red. In more severe cases, the stool can look almost entirely like blood with very little solid material. Some people also notice blood on the toilet paper after wiping, though that alone (without loose stool) points more toward hemorrhoids or a small tear near the anus than toward bloody diarrhea specifically.
Dark, Maroon, or “Currant Jelly” Stool
When blood has spent more time in the intestines before being passed, it oxidizes and darkens. Maroon-colored diarrhea suggests bleeding from the upper colon or small intestine. The stool often has a thicker consistency than bright red bloody diarrhea and may look like dark red or purplish jelly.
In children, a distinctive “currant jelly” stool, which looks like dark red mucus or preserves, is a hallmark of intussusception, a condition where part of the intestine folds into itself. This typically comes with episodes of cramping abdominal pain and vomiting. It’s a medical emergency in kids.
Black, Tarry Stool
Bleeding that starts high in the digestive tract, such as the stomach or upper small intestine, produces black, tarry stools. The blood turns dark because hemoglobin (the protein in red blood cells) gets broken down by digestive enzymes as it passes through the entire length of the gut. The result is stool that looks like tar or coffee grounds: sticky, very dark, and with a distinctly foul smell that’s different from normal stool.
This type of bleeding can accompany diarrhea, but even without loose stools, black tarry bowel movements signal active bleeding and should be taken seriously.
Blood With Mucus
Bloody diarrhea that also contains visible mucus, a clear or whitish slimy substance, points toward inflammation in the lining of the colon. This combination is common in inflammatory bowel diseases like ulcerative colitis and Crohn’s disease, where the immune system attacks the intestinal lining. The stool often looks like it has streaks or globs of bloody, jelly-like mucus mixed in with loose or watery material.
Bacterial infections can also produce mucus-heavy bloody stool. When pathogens like Shigella, Campylobacter, or certain strains of E. coli invade the intestinal wall, they trigger an inflammatory response. The resulting diarrhea tends to be frequent, watery or loose, and often contains both blood and mucus alongside a fever. This pattern, bloody diarrhea with fever, is sometimes called dysentery and is a strong indicator of a bacterial or parasitic infection rather than a dietary issue.
What Causes the Different Appearances
The visual differences come down to three factors: where the bleeding originates, how much blood is present, and whether there’s active inflammation.
- Infections: Bacteria like Salmonella, Shigella, Campylobacter, and certain E. coli strains cause inflammatory diarrhea that’s often watery with visible blood and mucus, paired with fever and cramping.
- Inflammatory bowel disease: Ulcerative colitis and Crohn’s disease produce chronic or recurring bloody diarrhea, frequently with mucus. Flares can last days to weeks.
- Diverticular bleeding: Pouches in the colon wall can bleed suddenly, producing large volumes of bright red or maroon blood mixed with stool.
- Stomach or upper intestinal bleeding: Ulcers or other upper GI sources produce the black, tarry appearance described above.
In children specifically, causes differ somewhat from adults. Milk protein allergy in infants can cause fussiness and blood-streaked stools, though frank diarrhea is uncommon with this condition. Intussusception produces the currant jelly stool mentioned earlier. Infectious diarrhea in kids looks similar to what adults experience but is considered more urgent because children dehydrate faster.
Foods and Medications That Mimic Blood
Before assuming the worst, it’s worth considering what you’ve eaten or taken recently. Beets and foods with red food coloring can turn stool reddish, which looks alarming in the toilet. On the darker end, iron supplements, black licorice, blueberries, blood sausage, activated charcoal, and bismuth-containing medications like Pepto-Bismol all cause black stools that can be mistaken for tarry, blood-containing stool.
The key difference is texture and smell. Stool that’s black from food or medication tends to be firm or normal in consistency and doesn’t have the sticky, tar-like quality or unusually strong odor of true upper GI bleeding. If you’ve recently eaten beets and your stool is reddish but otherwise normal in consistency and you feel fine, that’s likely the explanation. If you’re unsure, the discoloration from food typically resolves within a day or two of stopping the food.
Signs That Need Immediate Attention
Acute bloody diarrhea is generally considered a medical emergency, particularly when it’s accompanied by other warning signs. Large volumes of blood, whether bright red or dark, suggest significant bleeding that can lead to dangerous fluid loss. Dizziness, a racing heartbeat, feeling faint when standing, or confusion all point to dehydration or blood loss that’s affecting circulation.
Bloody diarrhea with a high fever suggests an invasive infection that may need targeted treatment. In children of any age, bloody diarrhea warrants prompt medical evaluation because dehydration develops quickly and certain pediatric causes like intussusception require urgent intervention. Persistent bloody diarrhea lasting more than a couple of days, or any episode severe enough to make you feel weak or lightheaded, is worth getting evaluated rather than waiting out.