Blood in Stool: Causes, Warning Signs, and When to Get a Colonoscopy

September 9, 2026

Noticing blood in the toilet or on toilet paper is unsettling, and it’s one of the most common reasons people search for answers before they pick up the phone to call a doctor. If this just happened to you, take a breath. Blood in stool is more common than most people realize, and it’s never something to dismiss, but it also doesn’t automatically mean something serious.

Below, we’ll walk through what different colors and types of bleeding usually mean, the most common causes, the warning signs that call for prompt attention, and how to get evaluated, including a direct path to a colonoscopy at our Phoenix and Gilbert, AZ offices without needing a referral first.

What Does Blood in Stool Look Like?

Bright red blood, whether in the toilet bowl, on the stool itself, or on toilet paper, usually points to bleeding low in the digestive tract, from the rectum, anus, or colon. Dark, maroon, or black, tarry stool usually points to bleeding higher up, in the stomach or small intestine, since blood darkens the further it travels through digestion.

That distinction matters because it’s often the first clue in figuring out what’s going on:

• Bright red blood: commonly from hemorrhoids, anal fissures, or bleeding low in the colon.
• Dark, maroon, or black, tarry stool: commonly from bleeding higher in the digestive tract, and typically comes with a stronger odor

It also helps to notice how the blood appears. Blood that streaks the surface of the stool or shows up only on toilet paper tends to point toward a source closer to the anus, like a fissure or external hemorrhoid. Blood that’s mixed throughout the stool, rather than sitting on the surface, can point to a source further up in the colon. Mucus alongside blood is also worth mentioning to your doctor, since it can be a sign of inflammation.

Blood When You Wipe

Bright red blood that only shows up on the toilet paper, not mixed into the stool itself, often points to something at the anus or lower rectum, most commonly a small tear (anal fissure) or an external hemorrhoid. Blood mixed into the stool or floating in the toilet water can still be minor, but it’s worth mentioning to a doctor regardless of how it looks.

Common Causes of Blood in Stool

Most cases of blood in stool are caused by common, treatable conditions like hemorrhoids or anal fissures. But blood in stool can also signal something that needs medical evaluation, like diverticular bleeding, inflammatory bowel disease, polyps, or colorectal cancer, which is why any occurrence is worth mentioning to a doctor, even if it seems minor.

Hemorrhoids

Hemorrhoids are swollen veins in the rectum or anus, and they’re extremely common. They often bleed bright red, especially after straining during a bowel movement, and can cause itching or discomfort. Most cases are manageable with hemorrhoid treatment and don’t require surgery. If you’re already dealing with ongoing symptoms, our guide on bleeding hemorrhoids covers treatment options in more depth.

Anal Fissures

Anal fissures are small tears in the lining of the anus, often caused by straining or passing a hard stool. They typically cause bright red blood and can sting or burn, especially right after a bowel movement. Many fissures heal on their own with dietary changes, but ongoing ones should be evaluated.

Diverticular Bleeding

As people age, small pouches called diverticula can form in the wall of the colon, a condition known as diverticulosis. These pouches are usually harmless on their own, but they can occasionally bleed, sometimes suddenly, painlessly, and in a noticeably larger amount than what you’d see with a hemorrhoid or fissure. Diverticular bleeding is actually one of the more common causes of sudden, significant rectal bleeding in older adults. It often stops on its own, but it still warrants a medical evaluation to confirm the source and rule out anything else going on.

Inflammatory Bowel Disease

Conditions like Crohn’s disease or ulcerative colitis cause ongoing inflammation in the digestive tract, which can lead to bleeding. This type of bleeding usually shows up alongside other symptoms, like diarrhea, cramping, or a frequent urge to go, and it tends to be recurring rather than a one-time occurrence. If you’re managing symptoms like these regularly, it’s worth a conversation with a gastroenterologist about what’s driving them, since inflammatory bowel disease responds much better to treatment when it’s identified and managed early rather than left to progress.

Polyps and Colorectal Cancer

Hemorrhoids are swollen veins in the rectum or anus, and they’re extremely common. They often bleed bright red, especially after straining during a bowel movement, and can cause itching or discomfort. Most cases are manageable with hemorrhoid treatment and don’t require surgery. If you’re already dealing with ongoing symptoms, our guide on bleeding hemorrhoids covers treatment options in more depth.

Polyps are growths that form in the lining of the colon. Most are harmless, but some can develop into colon cancer over time if left unchecked, which is the core reason screening matters.

According to the American College of Surgeons, rectal bleeding or blood in the stool is one of the recognized symptoms of colorectal cancer, alongside changes in bowel habits, unexplained weight loss, and fatigue. This doesn’t mean blood in your stool means cancer. Most causes are far less serious. But it’s exactly why any bleeding deserves a real evaluation rather than a guess.

Here’s the encouraging part: colon cancer is one of the more preventable cancers precisely because it usually starts as a polyp, and polyps can be found and removed during a colonoscopy before they ever get the chance to turn into cancer. That’s the real value of screening, it’s not just about detecting cancer early, it’s about catching and removing the thing that could become cancer in the first place. If you’d like to understand more about how symptoms can present, our article on symptoms of colon cancer goes into more detail.

When to Worry About Blood in Stool: Red Flag Symptoms

Seek medical attention if blood in stool is accompanied by dark or tarry stools, ongoing or heavy bleeding, unexplained weight loss, fatigue or weakness, a change in bowel habits lasting more than a few days, or abdominal pain. These combinations are more likely to point toward something that needs prompt evaluation rather than a minor, self-resolving cause.

Watch for:

• Dark, black, or tarry stools
• Bleeding that’s heavy, ongoing, or happens more than once
• Unexplained weight loss
• Fatigue or unusual weakness
• A change in bowel habits that lasts more than a few days
• Abdominal pain alongside the bleeding
• Blood clots in the stool

If bleeding is heavy, you’re feeling dizzy or lightheaded, or you suspect significant blood loss, that calls for immediate care rather than a scheduled appointment. A blood clot in the stool on its own isn’t automatically an emergency, but it’s a detail worth telling your doctor about specifically, since it can help pinpoint where the bleeding is coming from.

Why Am I Pooping Blood With No Pain?

Painless bleeding is common, especially with internal hemorrhoids, which often aren’t sensitive to touch the way external ones can be. But painless bleeding still deserves evaluation. Some more serious causes, including early colorectal cancer, can also be entirely painless, which is exactly why the absence of pain shouldn’t be read as a sign that nothing’s wrong. Pain, or the lack of it, tells you less than most people assume. What matters more is getting the actual cause identified, and how often it happens. A single instance after a bout of constipation is different from bleeding that keeps showing up week after week, and that pattern is one of the first things your provider will want to know about.

When to Get a Colonoscopy

Any unexplained or recurring blood in stool is a reason to talk with a gastroenterologist, and a colonoscopy is often the most direct way to find out exactly what’s causing it. The American Cancer Society recommends that average-risk adults begin routine colorectal cancer screening at age 45. But blood in stool at any age is a reason to be evaluated sooner, not a reason to wait for a routine screening age to roll around.

At Digestive Institute of Arizona, getting evaluated doesn’t require jumping through hoops first. Our Direct Screen Colonoscopy Program allows patients to schedule a screening colonoscopy directly, without needing a referral from a primary care doctor first. It’s a faster, more straightforward path to answers, available at both our Phoenix and Gilbert, AZ locations.

If you haven’t had one before, a colonoscopy is more straightforward than most people expect. It’s a minimally invasive procedure, typically taking 30 to 60 minutes, done under sedation so you’re comfortable throughout. Your gastroenterologist examines the entire colon and rectum for irregularities, and if a polyp is found, it can often be removed during the same procedure, no separate appointment needed. Most patients rest briefly afterward as the sedation wears off and are able to go home the same day with someone else driving.

FAQs

Q1. What does blood in stool mean?

It can come from a range of causes, from common and minor ones like hemorrhoids or fissures to more serious conditions like diverticular bleeding, inflammatory bowel disease, or colorectal cancer. The color and any accompanying symptoms help narrow it down, but a doctor’s evaluation is the only way to know for sure.

Q2. Is bright red blood in stool serious?

Not always. It’s often caused by hemorrhoids or fissures. But bright red blood can also come from more serious sources further up the colon, so it’s worth having evaluated, especially if it happens more than once.

Q3. What does dark or black stool mean?

Dark, tarry stool can indicate bleeding higher in the digestive tract, such as the stomach, and should be evaluated promptly, even if there’s no pain involved.

Q4. Can stress cause blood in stool?

Stress itself doesn’t cause bleeding, but it can worsen conditions like IBS or inflammatory bowel disease that make bleeding more likely. Blood in stool should always be evaluated rather than attributed to stress alone.

Q5. Do I need a referral for a colonoscopy?

Not at Digestive Institute of Arizona. Our Direct Screen Colonoscopy Program lets you schedule a screening colonoscopy directly, without a primary care referral, at our Phoenix or Gilbert offices.

Q6. At what age should I get screened for colon cancer?

The American Cancer Society recommends average-risk adults begin screening at 45. If you’re experiencing blood in stool at any age, that’s a reason to get evaluated sooner rather than waiting for a routine screening age.

If you’re noticing blood in your stool, don’t wait to have it checked out. Book an appointment at one of our Phoenix or Gilbert – AZ locations and let our team help you get real answers.

This article is for educational and informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.