Blood in your poop is common, but it is not normal. About one in seven adults report rectal bleeding over any given 12-month period, and younger people actually experience it more often than older adults. While the cause is usually something minor like hemorrhoids or a small tear, blood in your stool always signals that something is bleeding somewhere in your digestive tract, and that deserves attention.
The Most Common Causes Are Minor
The vast majority of rectal bleeding in otherwise healthy people comes from two sources: hemorrhoids and anal fissures. Both result from straining during bowel movements, and both produce bright red blood you might notice on toilet paper, in the bowl, or on the surface of your stool.
Hemorrhoids are swollen blood vessels around your anus that can bleed when irritated. They don’t always hurt, which is why you might see blood without any other symptoms. Anal fissures, on the other hand, are small tears in the lining of your anus. The tissue inside your anus is thinner and more delicate than regular skin, making it easy to tear with hard or large stools. About 90% of fissures cause pain, typically a sharp sting during a bowel movement that fades afterward. Hemorrhoid pain, when present, tends to be more constant. That timing difference is a useful way to tell them apart.
Fissures can get stuck in a frustrating cycle. The pain causes your anal muscles to clench and spasm, which pulls the tear apart and reduces blood flow to the area. That makes healing slower, which causes more pain, which causes more clenching. Softening your stool with fiber and water is the most effective way to break that loop.
What the Color Tells You
The color of blood in your stool reveals roughly where in your digestive tract the bleeding is coming from.
- Bright red blood generally comes from the lower digestive tract: the colon, rectum, or anus. Hemorrhoids, fissures, polyps, and inflammation in the colon are typical sources.
- Dark red or maroon blood mixed into the stool can indicate bleeding deeper in the colon or small intestine. Diverticulosis (small pouches in the colon wall that can bleed) is one common cause.
- Black, tarry, sticky stool usually means bleeding higher up, in the stomach or upper intestine. Digestive enzymes break down the blood as it passes through, turning it dark and giving it a distinctive foul smell. Stomach ulcers, severe acid reflux, and inflammation of the stomach lining are frequent causes. It takes a relatively small amount of blood, roughly half a cup, to produce this effect.
Black tarry stool is generally more concerning than a streak of bright red on toilet paper, because upper digestive bleeding tends to involve larger volumes and more serious conditions. That said, any persistent bleeding warrants investigation regardless of color.
Foods and Medications That Mimic Blood
Before assuming the worst, consider what you’ve eaten or taken recently. Beets contain a red pigment called betanin that can turn your stool a convincing blood-red. Cherries, tomatoes, and foods with red dyes can do the same. On the darker end, Pepto-Bismol can turn stool jet black, and so can iron supplements (which may produce a dark green or black color). Even eating large amounts of brightly colored candy can mix pigments in your gut and produce black stool.
If you suspect a food is the culprit, stop eating it for a few days. If the color returns to normal, you have your answer.
Medications That Cause Real Bleeding
Several common medications increase your risk of actual digestive tract bleeding. Anti-inflammatory painkillers like ibuprofen and naproxen are among the most frequent culprits. Low-dose aspirin, widely used for heart protection, raises the risk of upper gastrointestinal bleeding by roughly two to four times compared to not taking it.
The risk climbs sharply when these drugs are combined with each other or with certain other medications. Taking an anti-inflammatory painkiller alongside a corticosteroid (like prednisone) increases bleeding risk nearly 13-fold. Combining anti-inflammatories with blood thinners raises it about 9-fold. Even antidepressants in the SSRI class (commonly prescribed medications like sertraline or fluoxetine) can amplify bleeding risk when taken with painkillers, pushing it up to 7 times higher than baseline. If you take any combination of these medications and notice blood in your stool, that information is important to share with your doctor.
Red Flags That Need Quick Attention
Most rectal bleeding is not an emergency, but certain patterns suggest something more serious. Blood in your stool alongside unexplained weight loss, persistent fatigue, or a change in appetite raises the possibility of colorectal cancer or inflammatory bowel disease. A sudden change in the shape of your stool, particularly if it becomes consistently thin like a pencil, is another warning sign. Feeling like you need to have a bowel movement when you don’t, or feeling bloated or full all the time, also warrants investigation. Symptoms that come on suddenly and last more than two weeks should prompt a visit to your doctor.
Inflammatory bowel diseases like ulcerative colitis and Crohn’s disease cause chronic inflammation in the digestive tract and often produce bloody stool along with cramping, diarrhea, and fatigue. These are autoimmune conditions that, over time, also raise the risk of colorectal cancer.
Heavy bleeding is a different situation entirely. If you’re passing large amounts of blood, feeling dizzy or lightheaded when you stand up, or your heart is racing, those are signs of significant blood loss that needs emergency care.
Screening and Testing
The U.S. Preventive Services Task Force recommends that all adults begin routine colorectal cancer screening at age 45 and continue through age 75. This applies to people at average risk, with no symptoms and no family history. If you’re experiencing rectal bleeding, your doctor may recommend testing regardless of your age.
The simplest screening tool is a stool test, either a fecal occult blood test or a fecal immunochemical test (FIT). These check for hidden blood you can’t see with the naked eye. They’re noninvasive and done at home, but they can miss some polyps and cancers, and they sometimes flag blood that turns out to be insignificant.
Colonoscopy remains the most thorough option. A small camera examines the entire colon, and if polyps are found, they can often be removed during the same procedure. It’s not perfect either, as very small polyps can occasionally be missed, but it’s the most sensitive screening tool available. Your doctor will decide which test makes sense based on your age, symptoms, and family history.