Bleeding when you poop is almost always caused by something in the lower part of your digestive tract, and the most common culprits are hemorrhoids and anal fissures. These two conditions account for the majority of cases, especially in adults under 30. While the sight of blood can be alarming, it often points to something treatable. That said, the color, amount, and accompanying symptoms all matter in figuring out what’s going on.
Hemorrhoids: The Most Common Cause
Hemorrhoids are swollen blood vessels in or around the anus. They’re extremely common and often develop from straining during bowel movements, sitting for long periods, or chronic constipation. You might notice bright red blood on the toilet paper, in the bowl, or coating the stool. Most hemorrhoids don’t actually cause pain, which surprises many people. What they do cause is itching, mild discomfort, and sometimes a noticeable lump or swelling near the anus.
Internal hemorrhoids, which sit inside the rectum, are the ones most likely to bleed. You may not even feel them. External hemorrhoids, closer to the surface, are more likely to itch or feel sore, particularly if a blood clot forms inside one.
Anal Fissures: When It Hurts Too
If the bleeding comes with a sharp, stinging pain during or after your bowel movement, an anal fissure is more likely. A fissure is a small tear in the lining of the anus, usually caused by passing a large or hard stool. The blood is typically bright red and shows up on the toilet paper or on the surface of the stool. Unlike hemorrhoids, fissures tend to cause a burning or stinging sensation that can linger for minutes to hours after you go. Some people also notice itching that doesn’t go away between bowel movements.
Most fissures heal on their own within a few weeks, especially if you soften your stools and avoid straining. Chronic fissures that don’t heal may need further treatment.
What the Color of Blood Tells You
Bright red blood generally comes from the lower digestive tract: the rectum, anus, or lower colon. This is the type you’ll see with hemorrhoids, fissures, and a few other conditions discussed below.
Dark, tarry, almost black stools point to bleeding much higher up in the digestive tract, such as the stomach or upper intestines. Blood turns dark as it travels through the gut and gets broken down by digestive enzymes. If your stools look black and sticky rather than showing streaks of red, that’s a different situation entirely and warrants prompt medical attention.
Other Possible Causes
Diverticular Bleeding
Diverticulosis, where small pouches form in the walls of the colon, becomes increasingly common with age. About 30% of people over 50 and 75% of people over 80 have it. Roughly 10% of those people will experience some bleeding when hard stool passing through a pouch erodes a blood vessel. This bleeding is usually painless and temporary, producing fresh red blood in the stool. It often stops on its own, though about 3% of people with diverticulosis need treatment for persistent bleeding.
Inflammatory Bowel Disease
Conditions like Crohn’s disease and ulcerative colitis cause chronic inflammation in the digestive tract that can lead to rectal bleeding. The key difference here is that the bleeding rarely happens in isolation. It typically comes with other symptoms: abdominal pain, diarrhea (sometimes urgent), unexplained weight loss, fatigue, or nausea. If your bleeding is paired with any of these, it’s worth mentioning all of them to your doctor, not just the blood.
Colorectal Polyps or Cancer
This is the concern most people are really searching about. Polyps are small growths on the lining of the colon or rectum. Most are harmless, but some can become cancerous over time. Bleeding from polyps or colorectal cancer can look identical to hemorrhoid bleeding, which is why screening matters. The U.S. Preventive Services Task Force recommends that all adults begin colorectal cancer screening at age 45 and continue through age 75. If you’re under 45 but have persistent bleeding, a family history of colorectal cancer, or other concerning symptoms, screening may still be appropriate.
What to Expect at the Doctor’s Office
Your doctor will likely start by asking about your bowel habits, what the blood looks like, how often it happens, and whether you have any other symptoms. A physical exam of the area is standard. For many people, especially younger adults with clear hemorrhoid or fissure symptoms, that’s enough to make a diagnosis.
If the cause isn’t obvious, or if you’re over 45 and haven’t been screened, a colonoscopy is the go-to test. It allows a direct look at the entire colon and rectum, and it’s highly effective at identifying the source of bleeding. For younger patients with suspected anal or rectal causes, a more limited exam of the lower colon may be sufficient.
How to Prevent It From Happening Again
Most bleeding from hemorrhoids and fissures comes down to one thing: straining. Hard stools force you to push, which puts pressure on blood vessels and can tear delicate tissue. The single most effective change you can make is getting more fiber into your diet. The current dietary guidelines recommend 14 grams of fiber per 1,000 calories you eat, which works out to about 28 grams a day on a standard 2,000-calorie diet. Most people fall well short of this.
Good sources include beans, lentils, whole grains, fruits, and vegetables. If you’re not used to eating much fiber, increase your intake gradually over a week or two to avoid bloating and gas. Drinking enough water is equally important because fiber needs fluid to soften stool effectively. Without adequate hydration, adding fiber can actually make constipation worse.
Beyond diet, avoid sitting on the toilet longer than necessary. Scrolling your phone for 15 minutes while sitting puts sustained pressure on the veins around your anus. Go when you feel the urge, and get up when you’re done.
Signs That Need Immediate Attention
A small amount of bright red blood on the toilet paper after a hard bowel movement is usually not an emergency. But certain combinations of symptoms signal something more serious. Seek emergency care if rectal bleeding is continuous or heavy, or if it comes with severe abdominal pain or cramping.
Call 911 if you have significant bleeding along with any signs that your body isn’t handling the blood loss well: rapid or shallow breathing, dizziness or lightheadedness when you stand up, blurred vision, fainting, confusion, cold or clammy skin, or very little urine output. These suggest your blood pressure is dropping and you need help quickly.