A small amount of bright red blood in your stool is usually caused by hemorrhoids or a tiny tear in the skin around your anus. These two conditions account for the vast majority of minor rectal bleeding, and neither is dangerous. That said, blood in your stool always deserves attention, because the color, amount, and accompanying symptoms can point to a wide range of causes, some of which do need medical evaluation.
What the Color of the Blood Tells You
The shade of blood you see is a rough map of where the bleeding is coming from. Bright red blood typically originates near the end of the digestive tract: the rectum, anus, or lower colon. This is the most common type people notice on toilet paper or in the bowl, and it’s the kind most often linked to minor causes.
Dark maroon blood, sometimes mixed with clots, generally comes from higher up in the colon. Black, tarry, sticky stool with a strong odor points to bleeding in the upper digestive tract, such as the stomach or upper small intestine. Blood that travels a longer distance through the gut gets broken down along the way, which is what turns it dark. If your stool looks black and tar-like rather than bright red, that’s a different situation worth prompt medical attention.
Hemorrhoids: The Most Common Cause
Internal hemorrhoids are swollen blood vessels inside the rectum, and they’re extremely common. Most don’t cause pain at all. You might notice a small streak of bright red blood on the toilet paper or a few drops in the bowl after a bowel movement. The bleeding happens because straining or passing a hard stool puts pressure on these swollen vessels.
External hemorrhoids, which form under the skin around the anus, are more likely to cause itching and mild discomfort. Either type can bleed, and the blood is almost always bright red because the source is so close to the surface. Hemorrhoids often improve on their own with more fiber, more water, and less straining.
Anal Fissures: Small Tears, Sharp Pain
An anal fissure is a small tear in the lining of the anus, usually caused by passing a large or hard stool. Unlike hemorrhoids, fissures tend to hurt, sometimes intensely, during and after a bowel movement. You’ll often notice a sharp, burning pain along with a small amount of bright red blood when you wipe.
Fissures heal on their own in most cases within a few weeks, especially if you soften your stool with fiber and stay hydrated. Persistent fissures that don’t heal may need further treatment, but the initial approach is the same as for hemorrhoids: make bowel movements easier to pass.
Foods and Supplements That Mimic Blood
Before assuming the worst, consider what you’ve eaten recently. Beets contain a red pigment called betanin that can turn stool a convincing blood-red color. Large amounts of red candy, red gelatin, or tomato-based foods can do the same. On the darker end, black licorice, Pepto-Bismol, and iron supplements can all turn stool jet black, which might look alarming if you’re not expecting it.
If you recently ate any of these and feel perfectly fine otherwise, the color change is likely dietary. It should resolve within a day or two once the food passes through your system.
Infections That Cause Bloody Stool
Certain bacterial infections can inflame the lining of the colon enough to cause visible bleeding. A specific strain of E. coli (the type responsible for hemorrhagic colitis) and Shigella are among the more common culprits. These infections usually come with obvious additional symptoms: diarrhea, cramping, fever, and general misery.
If your bloody stool showed up alongside sudden diarrhea and stomach pain, especially after eating undercooked food or traveling, an infection is a likely explanation. Most cases resolve within a week, but some strains can cause serious complications, particularly in young children and older adults.
Medications That Increase Bleeding Risk
Common pain relievers like ibuprofen and aspirin can irritate the lining of your stomach and intestines, sometimes causing bleeding you wouldn’t otherwise experience. Daily aspirin regimens, even at low doses, increase the risk of gastrointestinal bleeding. The tricky part is that these medications can cause serious internal damage without any warning symptoms beforehand. Risk factors include older age, higher doses, a history of ulcers, and combining these medications with blood thinners or corticosteroids.
If you take any of these regularly and notice blood in your stool, that’s worth bringing up with your doctor, even if the amount seems small.
Less Common but More Serious Causes
Several conditions beyond hemorrhoids and fissures can cause rectal bleeding, and they’re worth knowing about even though they’re less likely to be responsible for a small amount of blood.
Diverticular bleeding happens when small pouches in the colon wall (diverticula) rupture a blood vessel. It typically shows up as a sudden, painless episode of moderate to heavy bleeding, with bright red to dark maroon stool, sometimes mixed with clots. This is more common in people over 60.
Inflammatory bowel disease, which includes Crohn’s disease and ulcerative colitis, causes chronic inflammation in the digestive tract. The hallmark is bloody diarrhea that comes back repeatedly, often paired with abdominal pain, weight loss, and fatigue over weeks or months. A single episode of minor bleeding is unlikely to be IBD, but recurring bloody diarrhea is a pattern worth investigating.
Colorectal cancer is understandably the concern that brings most people to search this question. Rectal bleeding is one of the more common symptoms of colon cancer. Nearly half of younger adults diagnosed with colon cancer had rectal bleeding as a symptom. However, the bleeding from cancer rarely shows up as a one-time small streak. It’s more often persistent, may be accompanied by changes in bowel habits, unexplained weight loss, or a feeling that your bowel doesn’t fully empty. The U.S. Preventive Services Task Force recommends that most people begin routine colorectal cancer screening at age 45, but if you’re having symptoms like rectal bleeding, screening guidelines don’t apply the same way. Symptomatic bleeding calls for diagnostic testing regardless of your age.
When Blood in Your Stool Needs Urgent Attention
A small amount of bright red blood after straining, with no other symptoms, is rarely an emergency. But certain combinations of symptoms call for immediate care. Get to an emergency room if rectal bleeding is continuous or heavy, or if it comes with severe abdominal pain or cramping.
Call 911 if you’re bleeding from the rectum and experience any signs of significant blood loss: dizziness or lightheadedness when you stand up, rapid shallow breathing, confusion, blurred vision, fainting, cold or clammy skin, nausea, or very low urine output. These signs suggest your body is losing blood faster than it can compensate.
What to Do Next
If you’ve noticed a small amount of bright red blood once or twice, with no pain and no other symptoms, hemorrhoids or a fissure are the most probable explanation. Increasing your fiber intake, drinking more water, and avoiding straining during bowel movements will address both of those causes.
If the bleeding keeps happening, shows up in larger amounts, or comes with changes in your bowel habits, abdominal pain, or weight loss, get it evaluated. Your doctor will likely start with a physical exam and may recommend a colonoscopy to look directly at the lining of your colon. If you’re 45 or older and haven’t had a screening colonoscopy yet, recurrent bleeding is a good reason to schedule one.