Bleeding when you poop is surprisingly common. Roughly one in seven adults report experiencing rectal bleeding at some point, and the most frequent causes are minor, treatable conditions like hemorrhoids and anal fissures. That said, the color of the blood, the amount, and any symptoms that come with it all matter. Understanding what’s behind the bleeding helps you figure out whether it’s something you can manage at home or something that needs a closer look.
The Most Common Causes
Hemorrhoids and anal fissures account for the vast majority of rectal bleeding, especially in younger adults. They’re different problems, but both involve the tissue in and around your anus.
Hemorrhoids are swollen blood vessels inside or just outside the rectum. Most don’t cause pain. You might notice bright red blood on the toilet paper or in the bowl, along with itching, mild discomfort, or small lumps near the anus. Straining during bowel movements, sitting for long periods, and pregnancy all increase your risk.
Anal fissures are small tears in the skin lining the anus. They’re more painful than hemorrhoids, often causing a sharp or burning sensation during and after a bowel movement. You’ll typically see blood when you wipe. Fissures usually happen when you pass a large or hard stool, and the pain can linger as itching or burning that doesn’t go away quickly.
What the Color of Blood Tells You
The appearance of blood in or on your stool gives a rough indication of where the bleeding is coming from. Bright red blood almost always points to a source near the end of the digestive tract: the rectum, anus, or lower colon. This is the type you’d expect with hemorrhoids, fissures, or inflamed tissue in the lower bowel.
Dark red or maroon-colored blood typically comes from higher up in the colon or sometimes the small intestine. Black, tarry stools suggest bleeding even further upstream, often in the stomach or upper small intestine. It takes roughly 100 to 200 milliliters of blood in the upper digestive tract to produce that tarry appearance, and stools can remain dark for several days after the bleeding has actually stopped. If your stool looks black and sticky rather than just dark from food, that’s a signal to get evaluated promptly.
Less Common but Serious Causes
Inflammatory Bowel Disease
Ulcerative colitis causes chronic inflammation and ulcers in the lining of the colon and rectum. When the inflammation is limited to the rectum, rectal bleeding may be the only symptom. More widespread disease brings diarrhea (often with blood or mucus), abdominal cramping, urgency, fatigue, fever, and unintentional weight loss. The underlying problem is an immune system that mistakenly attacks the cells of the digestive tract, leading to ongoing damage. Crohn’s disease, the other major form of inflammatory bowel disease, can affect any part of the digestive tract and also causes bleeding, though its pattern tends to be different.
Colon Polyps
Polyps are small growths on the inner wall of the colon. Most cause no symptoms at all, and many people only discover them during a screening colonoscopy. When polyps do bleed, it often happens slowly over weeks or months, without any visible blood in the stool. Instead, you may develop iron deficiency anemia, feeling unusually tired or short of breath. Larger polyps are more likely to cause noticeable changes: red streaks in the stool, darker stool color, or shifts in bowel habits like constipation or diarrhea lasting more than a week. Certain types of polyps, particularly villous adenomas and large sessile serrated lesions, carry a higher risk of becoming cancerous over time, which is why finding and removing them early matters.
Colorectal Cancer
Rectal bleeding can be an early sign of colorectal cancer, though it’s far from the most likely explanation. Cancer-related bleeding tends to be persistent, often accompanied by unexplained weight loss, a change in the caliber or frequency of your stools, or a feeling that your bowel doesn’t fully empty. The risk rises with age, which is one reason screening recommendations exist.
Medications That Increase Bleeding Risk
If you take blood thinners, aspirin, or common over-the-counter pain relievers like ibuprofen or naproxen, you have a higher chance of gastrointestinal bleeding. These medications affect your body’s ability to form clots or protect the stomach and intestinal lining. Anticoagulants, antiplatelet drugs, and NSAIDs are all independently associated with elevated risk for upper GI bleeding. That doesn’t mean you should stop taking a prescribed medication because you notice some blood, but it’s important context to share with your doctor.
When Rectal Bleeding Needs Urgent Attention
A small amount of bright red blood on the toilet paper after straining is rarely an emergency. But certain combinations of symptoms signal that you need immediate medical care. Go to the emergency room 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 of shock: rapid or shallow breathing, dizziness or lightheadedness when you stand up, blurred vision, fainting, confusion, nausea, cold or clammy skin, or very low urine output. These signs mean your body is losing blood faster than it can compensate.
How Doctors Figure Out the Cause
The evaluation depends on your age, symptoms, and how the bleeding looks. For suspected hemorrhoids or fissures, a doctor may use an anoscope, a short tube about 7 centimeters long that examines the anal canal and lower rectum. It requires no preparation and takes just a few minutes.
If the source might be higher up, a sigmoidoscopy uses a flexible tube to examine the rectum and sigmoid colon (the lower portion of the large intestine). This requires an enema beforehand but usually no sedation. A full colonoscopy examines the entire colon and is the standard test when there’s concern about polyps, inflammatory bowel disease, or cancer. It requires a bowel prep the day before and sedation during the procedure.
Current guidelines from the U.S. Preventive Services Task Force recommend that most adults begin routine colorectal cancer screening at age 45, continuing through age 75. You may need to start earlier if you have inflammatory bowel disease, a personal or family history of colorectal cancer or polyps, or a genetic condition like Lynch syndrome.
Preventing Bleeding From Straining
Since straining is the trigger behind most hemorrhoid and fissure bleeding, keeping your stools soft is the single most effective preventive measure. That comes down to fiber and water. The National Academy of Medicine recommends 25 grams of fiber per day for women 50 and younger (21 grams over 50) and 38 grams for men 50 and younger (30 grams over 50). Most Americans fall well short of these targets.
Fiber works best when it absorbs water, which is what makes stool soft, bulky, and easier to pass. Increasing fiber without drinking enough fluid can actually make constipation worse. Good sources include beans, lentils, whole grains, vegetables, fruits, and nuts. If you’re significantly below the target, increase your intake gradually over a couple of weeks to avoid gas and bloating. Avoiding long periods of sitting on the toilet and not delaying the urge to go also reduce pressure on the rectal veins that lead to hemorrhoids.