Red stool usually comes from something you ate, but it can also signal bleeding somewhere in your digestive tract. The most important first step is figuring out whether the red color is actually blood or just a harmless pigment from food. In many cases, the answer is simple and nothing to worry about. But when it is blood, the color, amount, and accompanying symptoms tell you a lot about what’s going on.
Foods and Medications That Turn Stool Red
Before assuming the worst, think about what you’ve eaten in the last day or two. Beets are the most common culprit. They contain a deep red pigment that passes through your digestive system largely intact, and the result can look alarming in the toilet. Tomatoes, tomato sauce, red gelatin, cranberries, red velvet cake, and anything with red food coloring can do the same thing.
Certain medications also change stool color. Pepto-Bismol and iron supplements tend to make stool dark or black rather than red, but some antibiotics and anti-inflammatory drugs can irritate the gut lining enough to cause minor bleeding. If you recently started a new medication and notice a color change, that’s worth mentioning to your doctor. The key difference: food-related color changes are uniform throughout the stool, while blood often shows up as streaks, drops, or clots.
Bright Red Blood: What It Usually Means
Bright red blood in or on your stool typically comes from the lower part of the digestive tract, meaning the colon, rectum, or anus. The blood looks red because it hasn’t traveled far enough through the gut to be broken down by digestive enzymes. The most common causes are relatively minor.
Hemorrhoids are swollen blood vessels in or around the anus. Internal hemorrhoids (inside the rectum) often bleed painlessly. You might see bright red blood on the toilet paper or dripping into the bowl, but you won’t necessarily feel anything. External hemorrhoids, on the other hand, can itch, hurt, and sometimes develop a painful clot. Hemorrhoids are extremely common and are the single most frequent reason people see blood after a bowel movement.
Anal fissures are small tears in the skin around the anus, usually caused by passing hard or large stools. They tend to cause a sharp, stinging pain during bowel movements along with a small amount of bright red blood. These are especially common in people dealing with constipation and in young children during toilet training.
Diverticular bleeding happens when small pouches in the colon wall (which many adults develop with age) rupture a tiny blood vessel. This type of bleeding tends to come on suddenly and can be heavy for a short period, but it usually stops on its own without treatment.
Dark or Tarry Stool Is a Different Signal
If your stool looks black, sticky, and tar-like rather than red, that points to bleeding higher up in the digestive tract, such as the stomach or upper small intestine. The blood turns dark because hemoglobin, the protein in red blood cells, gets broken down by digestive enzymes as it travels through the gut. This type of stool often has a distinctly foul smell.
Dark, tarry stool can indicate a stomach ulcer, inflammation of the stomach lining, or other upper digestive issues. It’s generally considered more urgent than a small streak of bright red blood, because bleeding from the upper tract tends to involve larger volumes.
When Red Stool Points to Something Serious
Most episodes of red stool turn out to be food-related or caused by hemorrhoids. But blood in the stool is also a symptom of conditions that need medical attention, including inflammatory bowel disease and colorectal cancer. What separates a minor issue from a serious one is usually the pattern of symptoms.
Colorectal cancer symptoms often include a persistent change in bowel habits (new diarrhea or constipation that doesn’t resolve), ongoing belly cramps or gas, a feeling that your bowel doesn’t fully empty, unexplained weight loss, and fatigue. Blood in the stool may be visible or hidden. A one-time episode of red stool with no other symptoms is far less concerning than recurring blood paired with any of those changes.
A study from the University of Louisville found that among adults under 50 who had colonoscopies, rectal bleeding was the strongest predictor of colorectal cancer, increasing the odds 8.5 times compared to people without bleeding. That doesn’t mean most rectal bleeding is cancer. It means rectal bleeding, especially when it’s new, recurring, or paired with other symptoms, deserves investigation rather than dismissal.
Red Stool in Babies and Children
Red stool in infants has its own set of causes, many of them harmless. Newborns sometimes swallow blood during delivery or from a cracked nipple during breastfeeding, and that blood passes through as red stool. Diaper rash can cause small amounts of blood around the anus that mix into the diaper. Female newborns occasionally have a brief vaginal discharge (sometimes called a “mini-period”) triggered by the withdrawal of the birth parent’s hormones after delivery.
In older babies and toddlers, food allergies are a notable cause. A protein allergy, most commonly to cow’s milk, can inflame the lining of the intestine and cause bloody stool. Constipation-related anal fissures are also very common during toilet training. Infections picked up from contaminated food or contact with other children can cause bloody diarrhea as well. If a child has red, jelly-like stool along with severe intermittent crying and pulling the legs up, that combination warrants immediate medical evaluation, as it can indicate a bowel obstruction called intussusception.
How Doctors Figure Out the Cause
If you see blood in your stool more than once, your doctor will likely start with a physical exam and a detailed history: what the blood looks like, how often it appears, and whether you have any other symptoms. For many people, that’s enough to identify hemorrhoids or fissures without further testing.
When the cause isn’t obvious, a colonoscopy is the most direct way to look at the entire colon and identify the source of bleeding. A stool test that detects hidden blood (the kind you can’t see) is often used as a screening tool, particularly for people who aren’t yet due for a colonoscopy. Your age, family history, and symptom pattern all factor into which tests your doctor recommends first.
Signs That Need Immediate Attention
A small amount of blood on toilet paper after straining doesn’t usually require a trip to the emergency room. But heavy or continuous rectal bleeding, especially with severe abdominal pain, is a different situation. If you’re passing a large amount of blood and experiencing rapid or shallow breathing, dizziness when you stand up, confusion, cold or clammy skin, blurred vision, or fainting, those are signs of significant blood loss that requires emergency care. The combination of heavy bleeding with any of those symptoms means your body is struggling to compensate for the blood you’re losing.