Blood in your stool is surprisingly common. Population studies estimate that roughly one in seven otherwise healthy adults have experienced rectal bleeding at some point. The causes range from completely harmless (hemorrhoids, a small tear) to conditions that need prompt medical attention, and the color of the blood is one of the best clues to what’s going on.
What the Color of the Blood Tells You
Bright red blood typically comes from the lower part of your digestive tract, meaning the colon, rectum, or anus. You might see it on the toilet paper, dripping into the bowl, or streaked on the surface of your stool. The most common cause of this type of bleeding is diverticulosis, where small pouches in the colon wall become clogged or infected. Hemorrhoids, anal fissures, and inflammation of the colon (from conditions like inflammatory bowel disease) are also frequent culprits.
Dark, tarry, almost black stool points to bleeding higher up, in the stomach or esophagus. Blood that travels through the full length of the digestive tract gets broken down by digestive enzymes, which turns it dark and gives it a sticky, tar-like consistency. The most common causes are stomach ulcers and inflammation of the esophagus or stomach lining. Less common causes include enlarged blood vessels in the digestive tract (a complication of liver disease) or a small tear where the esophagus meets the stomach, sometimes caused by forceful vomiting.
Hemorrhoids vs. Anal Fissures
These two are the most frequent benign explanations for bright red blood, and they feel quite different. Hemorrhoids, which are swollen blood vessels in or around the anus, usually don’t hurt. You’ll notice blood on the paper or in the bowl, sometimes with itching or a feeling of fullness near the anus, but the actual act of having a bowel movement isn’t painful. Internal hemorrhoids bleed more often than external ones.
Anal fissures are tiny tears in the skin lining the anus. They hurt, sometimes sharply, during and after a bowel movement. You’ll typically see a small amount of bright red blood on the tissue. Fissures are commonly triggered by passing a large or hard stool, and they tend to heal on their own within a few weeks if you keep stools soft.
Foods and Medications That Mimic Blood
Before assuming the worst, consider what you’ve eaten or taken recently. Beets, tomatoes, and anything with red food coloring can make stool look reddish in a way that’s easy to mistake for blood. On the dark end, blueberries, black licorice, blood sausage, iron supplements, activated charcoal, and bismuth (the active ingredient in Pepto-Bismol) can all turn stool black without any bleeding involved. If you recently consumed any of these, wait a day or two and see if the color returns to normal.
More Serious Causes
Inflammatory bowel disease, which includes ulcerative colitis and Crohn’s disease, can cause recurring blood in the stool. Ulcerative colitis in particular often produces bloody diarrhea because the inflammation is concentrated in the colon’s inner lining. Crohn’s disease, by contrast, usually causes diarrhea that is not bloody, though bleeding can still happen depending on where the inflammation is located. Both conditions come with other symptoms like persistent abdominal pain, urgency, fatigue, and unintentional weight loss.
Colorectal cancer is what most people fear when they see blood in their stool. While it accounts for a small fraction of rectal bleeding cases, it’s the reason screening matters. Warning signs that set cancer-related bleeding apart from hemorrhoids include a change in bowel habits lasting more than a few weeks (new constipation, narrower stools, or a feeling that your bowel doesn’t empty completely), unexplained weight loss, and persistent fatigue. Blood from a tumor may be mixed into the stool rather than sitting on top of it, and it can be intermittent enough that you don’t notice it without a screening test.
When Blood in Stool Is an Emergency
Most rectal bleeding doesn’t require a trip to the emergency room. But heavy or continuous bleeding, or bleeding paired with severe abdominal pain or cramping, warrants immediate medical attention.
Call 911 if you’re bleeding from the rectum and experiencing any signs of significant blood loss:
- Dizziness or lightheadedness when you stand up
- Rapid, shallow breathing
- Blurred vision or fainting
- Confusion
- Cold, clammy, or pale skin
- Very low urine output
These symptoms suggest your body isn’t circulating enough blood, and that requires urgent evaluation regardless of the underlying cause.
Managing Minor Bleeding at Home
If you’re dealing with occasional bright red blood and you suspect hemorrhoids or a fissure, a few simple changes often resolve it. Adding more fiber to your diet (fruits, vegetables, whole grains, or a fiber supplement) softens your stool and reduces straining, which is the primary driver of both conditions. Warm baths, particularly sitting in a few inches of warm water for 10 to 15 minutes, can soothe irritated tissue. Over-the-counter medicated creams designed for hemorrhoids can also help with swelling and discomfort.
Staying well hydrated works alongside fiber to keep stools soft. Avoid sitting on the toilet for long periods, and don’t strain or force a bowel movement. If bleeding persists beyond a week or two despite these measures, or if it’s your first time noticing blood and you’re unsure of the cause, getting checked is worthwhile even if the bleeding is minor.
Screening for Colorectal Cancer
The U.S. Preventive Services Task Force recommends that all adults begin colorectal cancer screening at age 45. From age 50 to 75, screening is strongly recommended for everyone at average risk. Between 76 and 85, the decision becomes more individualized based on your overall health and screening history.
You don’t necessarily need a colonoscopy to get screened. Several options exist: a stool-based test (FIT) done annually can detect hidden blood your eyes would miss, a stool DNA test every one to three years combines blood detection with genetic markers, and a colonoscopy every 10 years provides the most thorough visual exam. The right choice depends on your preferences, risk factors, and what your provider recommends. If you’ve noticed blood in your stool and you’re over 45 without a recent screening, that’s a reasonable prompt to schedule one.