Red poop is usually caused by something you ate, not by bleeding. Beets, red-dyed snacks, flavored gelatin, fruit punch, and red licorice can all turn your stool noticeably red. But when food isn’t the explanation, red stool can signal bleeding somewhere in the digestive tract, and the shade of red helps narrow down where.
Foods and Medications That Turn Stool Red
Before worrying about a medical cause, think back over the last day or two. The most common culprits are beets, red gelatin, red Kool-Aid or fruit punch, red licorice, and red-dyed snack foods (like spicy “red hot” chips). These can produce stool that looks strikingly like fresh blood, even though nothing is wrong.
Certain antibiotics can also give stool a reddish tint. In rare cases, antibiotics cause actual intestinal bleeding rather than just discoloration, so if the red color persists after finishing a course of antibiotics, it’s worth getting checked.
A simple way to test your suspicion: stop eating the red-colored food and wait one to two bowel movements. If the color returns to normal, you have your answer.
What the Shade of Red Tells You
When the red color isn’t from food, the specific shade matters. Bright red blood typically means the bleeding source is low in the digestive tract, in the colon, rectum, or anus. Darker, maroon-colored blood suggests a source higher up in the colon. Black or tar-like stool points to bleeding even further upstream, in the stomach or small intestine, where blood has been partially digested.
One useful detail: if you see blood only on the toilet paper but not mixed into the stool itself, the source is most likely hemorrhoids or a small tear in the skin around the anus (an anal fissure). Blood that’s mixed into the stool or that turns the toilet water red usually comes from somewhere inside the colon.
Common Causes of Bright Red Blood in Stool
Hemorrhoids are the single most common cause of visible rectal bleeding. These are swollen veins inside the rectum or anus that bulge close to the surface and sometimes break open. They’re extremely common, often painless, and tend to flare up with constipation or straining.
Anal fissures are the second major culprit. These are small tears in the lining of the anal canal, usually caused by passing a hard stool. They’re easily mistaken for hemorrhoids because both involve constipation, pain, and bleeding. The key difference is that fissures typically cause a sharp, stinging pain during bowel movements.
Diverticulitis can also cause noticeable rectal bleeding. This happens when small pockets in the inner lining of the colon become infected and inflamed, making the blood vessels inside them fragile and prone to rupturing. Diverticulitis is more common in people over 40 and often comes with abdominal pain, fever, and changes in bowel habits.
More Serious Causes to Be Aware Of
Inflammatory bowel diseases like Crohn’s disease and ulcerative colitis can cause chronic or recurring blood in the stool. These conditions involve ongoing inflammation in the digestive tract and usually come with other symptoms: persistent diarrhea, abdominal cramps, bloating, fatigue, and unintentional weight loss.
Colorectal cancer is less common but important to consider. One useful distinction from Johns Hopkins Medicine: hemorrhoid-related bleeding tends to come and go with flare-ups, while bleeding caused by cancer typically continues or worsens over time and is more likely to be accompanied by pain. Other warning signs of colorectal cancer include new changes in bowel habits (constipation or diarrhea that wasn’t there before), stools that are noticeably narrower than usual, a feeling that your bowel isn’t emptying completely, and unexplained weight loss.
Slowly bleeding tumors can also lose microscopic amounts of blood that don’t visibly change stool color at all. This hidden blood may only be detected through a screening test or when a blood test reveals anemia.
Red Stool in Babies and Young Children
In infants, the most common cause of blood-streaked stool is an allergy to cow’s milk protein, a condition called allergic colitis. It affects 2 to 3 percent of infants and typically shows up as small flecks or streaks of blood in the stool, along with extreme fussiness. It’s very treatable: removing cow’s milk protein from the baby’s diet (or the nursing mother’s diet) usually resolves it. About 30 percent of babies with this allergy also react to soy protein, so a soy-free formula may be needed if symptoms don’t clear up.
Red-dyed foods and drinks are another common cause in children, just as in adults. However, if a child on antibiotics develops red or bloody-looking stool, that warrants a call to the pediatrician, since antibiotics can occasionally cause real intestinal bleeding in children.
When Red Stool Needs Urgent Attention
Most causes of red stool are not emergencies, but certain combinations of symptoms are. Get to an emergency department if you have blood in your stool along with feeling faint, dizzy, or lightheaded. Nonstop bleeding, large blood clots, or toilet water that turns red all warrant immediate evaluation. Other red flags include chest pain, shortness of breath, vomiting blood, fever, significant unexplained weight loss, or jaundice (yellowing of the skin or eyes).
How Doctors Evaluate Blood in Stool
If you report blood in your stool, your doctor will likely start with a rectal exam. Depending on your age, symptoms, and risk factors, a colonoscopy may follow. For average-risk adults, the U.S. Preventive Services Task Force recommends routine colorectal cancer screening starting at age 45, even without symptoms. People with a family history of colorectal cancer or genetic conditions like Lynch syndrome may need screening earlier and more frequently.
When bleeding isn’t visible to the naked eye, doctors use a stool test called a FIT (fecal immunochemical test) to detect hidden blood. This test is specific to human blood, requires only a single stool sample, and has no food restrictions beforehand. It’s significantly more accurate than older stool tests and catches roughly twice as many cases of cancer and advanced precancerous growths. If the FIT is positive, a colonoscopy is the next step to find the source.
If you’re younger than 45 and having symptoms like persistent rectal bleeding, changes in bowel habits, or unexplained weight loss, a colonoscopy is still appropriate. Colorectal cancer rates in younger adults have been rising, and symptoms at any age deserve proper evaluation.