Blood in your poop is common, but it’s not normal. Most of the time the cause is something minor and treatable, like hemorrhoids or a small tear in the skin near your anus. But because blood in your stool can also signal more serious conditions, it’s worth paying attention to the details: the color, the amount, and any other symptoms you’re experiencing.
What the Color of the Blood Tells You
The color of the blood is one of the most useful clues about where the bleeding is coming from. Bright red blood typically originates from the lower part of your digestive tract, near the rectum or anus. This is the kind you might see on the toilet paper, on the surface of your stool, or dripping into the bowl. It hasn’t traveled far, so it still looks fresh.
Black, tarry-looking stool points to bleeding higher up in the digestive tract, such as the stomach or upper intestines. Blood turns dark as it moves through your system because digestive enzymes break down hemoglobin, the protein that gives blood its red color. By the time it reaches the other end, it looks black and often has a sticky, tar-like consistency. Maroon-colored stool falls somewhere in between and can indicate bleeding in the middle portions of the intestine.
The Most Common (and Least Serious) Causes
Hemorrhoids are the leading cause of bright red rectal bleeding in adults. These are swollen blood vessels in or around the anus that can bleed when you strain during a bowel movement. The bleeding can look dramatic, sometimes dripping into the toilet or leaving streaks on toilet paper, but hemorrhoids rarely cause enough blood loss to be dangerous. The discomfort tends to feel like a dull ache or itch rather than sharp pain.
Anal fissures, which are small tears in the lining of the anus, are the other common culprit. They tend to produce less blood than hemorrhoids but more pain. A sharp, burning sensation during and after a bowel movement that can linger for hours is the hallmark of a fissure. Both conditions are strongly associated with constipation, straining, and hard stools.
Foods and Medications That Mimic Blood
Before you worry, consider what you’ve eaten or taken recently. Beets and foods with red coloring can make stool appear reddish, closely mimicking the look of blood. On the other end of the spectrum, iron supplements, bismuth-containing antacids like Pepto-Bismol, black licorice, blueberries, and activated charcoal can all turn your stool black, imitating the appearance of upper digestive tract bleeding. If your stool looks alarming but you feel perfectly fine, run through your recent diet and medications first.
Infections That Cause Bloody Stool
Food poisoning and other gut infections can cause bloody diarrhea, often with sudden onset. Certain strains of E. coli, Shigella, and Yersinia are among the bacteria most likely to produce visible blood in your stool. These infections typically come with other symptoms: cramping, fever, nausea, and frequent watery or bloody diarrhea that starts within a few days of eating contaminated food or traveling somewhere with different sanitation standards. Most cases resolve on their own, though some bacterial infections need targeted treatment.
Inflammatory Bowel Disease
When bloody stool is ongoing rather than a one-time event, inflammatory bowel disease (IBD) becomes a more important consideration. IBD, which includes Crohn’s disease and ulcerative colitis, involves chronic inflammation of the digestive tract. The bleeding tends to come alongside other persistent symptoms: abdominal pain, frequent and urgent diarrhea, unintentional weight loss, fatigue, and sometimes fever. Some people also notice mucus in their stool.
IBD is different from irritable bowel syndrome (IBS), which does not involve inflammation and does not cause bleeding. If you’ve been told you have IBS but you’re seeing blood, that’s a reason to go back to your doctor for further evaluation.
Blood in Stool in Children
The causes differ somewhat by age. In newborns, swallowed maternal blood during delivery is one possibility, along with anal fissures. In older infants and children, the most common causes include anal fissures, food protein allergies (particularly to cow’s milk protein), infectious diarrhea, and juvenile polyps. Intussusception, a condition where one part of the intestine telescopes into another, is a less common but more urgent cause in young children that typically produces “currant jelly” stool along with severe cramping.
How Likely Is It to Be Cancer?
This is the fear behind most searches about blood in stool, so here are the numbers. Studies of patients who went to their doctor with new rectal bleeding found that colorectal cancer was the cause in roughly 2 to 7 percent of cases. In one study, among patients 45 and older with a new episode of rectal bleeding, about 1 in 18 was diagnosed with colorectal cancer, and about 1 in 20 had precancerous growths called adenomas. Taken together, roughly 1 in 10 patients with new rectal bleeding in that age group had some form of concerning growth.
That means the vast majority of rectal bleeding, even in older adults, turns out to be something benign. But it also means the risk isn’t trivial, particularly if you’re over 45, have a family history of colon cancer, are losing weight without trying, or notice a change in your bowel habits alongside the bleeding.
What Your Doctor Will Want to Know
If you do bring this up with a doctor, expect them to ask specific questions: what color the blood is, how much there is, how long it’s been happening, whether it’s on the surface of the stool or mixed in, whether your bowel habits have changed, and whether you have pain, fever, or weight loss. These details help narrow down the source before any tests are ordered.
For people under 40 where hemorrhoids are the likely explanation, a physical exam may be all that’s needed, unless red-flag symptoms like weight loss, anemia, or a family history of colon cancer are present. For older adults or anyone with concerning symptoms, a colonoscopy is the standard next step. This allows a doctor to visually inspect the entire colon and, if needed, remove polyps or take tissue samples during the same procedure.
Signs That Need Urgent Attention
A small streak of bright red blood on the toilet paper after straining is usually not an emergency. But certain combinations of symptoms call for immediate medical care. Heavy or continuous bleeding, severe abdominal pain or cramping, and any signs that you’re losing a significant volume of blood, such as dizziness when standing, rapid shallow breathing, confusion, fainting, cold and clammy skin, or blurred vision, all warrant a trip to the emergency room. These signs suggest enough blood loss to affect your circulation, which needs to be addressed quickly regardless of the underlying cause.