Bleeding when you poop is extremely common, affecting 10 to 20 percent of the general population at some point. In most cases, the cause is something minor like hemorrhoids or a small tear in the skin around your anus. But because bleeding can occasionally signal something more serious, it’s worth understanding what different types of bleeding look like, what causes them, and which signs should prompt a visit to your doctor.
What the Color of the Blood Tells You
The color and consistency of the blood you see is one of the most useful clues about where the bleeding is coming from. Bright red blood, whether it’s on the toilet paper, streaked on the surface of your stool, or dripping into the bowl, almost always comes from the lower part of your digestive tract: the rectum or anus. This is the most common type of bleeding people notice, and it’s the type most often caused by hemorrhoids or fissures.
Dark red or maroon-colored blood mixed into the stool typically points to bleeding higher up in the colon, from sources like polyps, diverticular disease, or inflammation. Black, tarry, sticky stools with a strong odor suggest the bleeding is coming from even further up, often the stomach or upper small intestine. Blood turns black as it’s digested during its journey through the gut. Very rarely, rapid bleeding from the upper digestive tract can produce bright red blood if the bleeding is fast enough that the blood doesn’t have time to darken.
Hemorrhoids: The Most Common Cause
Hemorrhoids are swollen blood vessels in or around the anus, and they’re by far the most frequent reason people see blood after a bowel movement. Internal hemorrhoids, which sit inside the rectum where you can’t see or feel them, often cause painless bleeding. You might notice bright red blood on the toilet paper or dripping into the bowl, with no discomfort at all. External hemorrhoids form under the skin around the outside of the anus and are more likely to cause a noticeable lump, itching, or pain, especially if a blood clot forms inside them.
Straining during bowel movements, sitting on the toilet for long periods, chronic constipation, and pregnancy all increase the risk of developing hemorrhoids. They account for roughly a third of all cases where people seek care for rectal bleeding.
Anal Fissures: When It Hurts Too
If the bleeding comes with a sharp, tearing pain during your bowel movement, an anal fissure is a likely culprit. A fissure is a small tear in the lining of the anus, usually caused by passing a hard or large stool. The pain can be intense during the bowel movement itself and may continue as a throbbing ache for several hours afterward. You’ll typically see bright red blood on the toilet paper or the surface of the stool, similar to hemorrhoids, but the pain is the distinguishing feature.
Most fissures heal on their own within a few weeks, especially if you soften your stools by increasing fiber and fluid intake. Fissures that persist beyond six to eight weeks are considered chronic and may need further treatment.
Other Conditions That Cause Bleeding
Beyond hemorrhoids and fissures, several other conditions can cause blood in your stool. Diverticular bleeding happens when small pouches in the colon wall (diverticula) rupture a blood vessel. This tends to cause sudden, painless bleeding that can be heavy, often producing dark red or maroon-colored stool. Diverticular disease becomes more common after age 40.
Inflammatory bowel diseases like Crohn’s disease and ulcerative colitis cause chronic inflammation in the digestive tract. Bleeding from these conditions is usually accompanied by other symptoms: persistent diarrhea, abdominal cramping, weight loss, and fatigue. If you’re experiencing bloody stools along with weeks of diarrhea or unexplained weight loss, these conditions are worth investigating.
Polyps, which are small growths on the inner lining of the colon, can bleed intermittently and often cause no other symptoms. Most polyps are harmless, but some can develop into cancer over time, which is one reason routine screening is important.
The Link to Colorectal Cancer
This is the possibility that worries most people, and it deserves a straight answer. About 6 percent of people over age 40 who see a doctor for rectal bleeding alone turn out to have colorectal cancer. That means the vast majority do not. But rectal bleeding is one of the strongest early warning signs of colorectal cancer, particularly in younger adults.
A National Cancer Institute analysis found that rectal bleeding had the strongest association with early-onset colorectal cancer of any warning sign studied. Other warning signs include abdominal pain, persistent diarrhea, and iron deficiency anemia (which can show up as unusual fatigue, pale skin, or shortness of breath). Having just one of these signs in the months before diagnosis was associated with roughly twice the likelihood of colorectal cancer compared to having none. Having three or more signs was linked to a sixfold increase in risk.
New cases of colorectal cancer in people under 50 have been climbing since the mid-1990s, which is why the U.S. Preventive Services Task Force now recommends that all average-risk adults begin screening at age 45, down from the previous recommendation of 50. If you have a family history of colorectal cancer or inflammatory bowel disease, screening may need to start even earlier.
What Happens During a Workup
A physical exam alone can’t reliably determine whether rectal bleeding is coming from something simple like hemorrhoids or something deeper in the colon. Even if a doctor finds hemorrhoids during an exam, that doesn’t rule out a second source of bleeding higher up. This is why many people with rectal bleeding are eventually referred for a colonoscopy, which was the most frequently performed diagnostic procedure in one large study of rectal bleeding workups, used in nearly half of all cases.
During a colonoscopy, a flexible camera is guided through the entire colon, allowing your doctor to see polyps, inflammation, diverticula, or other sources of bleeding directly. The procedure itself takes about 30 to 60 minutes, and the preparation (clearing out your bowels the day before) is generally considered the most unpleasant part. If polyps are found, they can usually be removed during the same procedure.
Signs You Should Act Quickly
Most rectal bleeding doesn’t require emergency care, but some situations do. Heavy bleeding that doesn’t stop, blood clots in your stool, or bleeding accompanied by dizziness, lightheadedness, a racing heartbeat, or feeling faint can indicate significant blood loss that needs immediate attention. These are signs your body is struggling to compensate for the volume of blood you’ve lost.
You should also seek prompt evaluation if you notice black, tarry stools, which suggest bleeding from the upper digestive tract, or if bleeding is accompanied by severe abdominal pain and fever, which could indicate an infection or a condition like diverticulitis.
Preventing Constipation-Related Bleeding
Since constipation and straining are behind many cases of hemorrhoids and fissures, keeping your stools soft is one of the most effective ways to prevent rectal bleeding from recurring. Fiber is the cornerstone: people who consume less than 25 grams of fiber per day are up to three times more likely to develop constipation-related complications, including bleeding. Most adults fall well short of that target.
A recent study using machine learning to identify dietary predictors found that people who ate less than 50 grams per day of boiled vegetables or oatmeal had a bleeding rate of nearly 44 percent, compared to those who ate more. Inadequate whole grain intake showed a similar pattern. Beyond diet, drinking at least two liters of fluid daily, staying physically active, and maintaining a regular sleep schedule all help keep your digestive system moving smoothly. On the toilet, avoid straining or sitting for extended periods. If you feel the urge, go promptly rather than holding it, which can harden the stool and set the stage for tearing.