Normal poop is brown because of a pigment called stercobilin, a byproduct of bile that gets chemically transformed by gut bacteria as it travels through your digestive tract. When something disrupts that process, whether it’s food, medication, or a medical condition, the color shifts. Most color changes are harmless and temporary, but a few are worth paying attention to.
Why Poop Is Brown in the First Place
Your liver produces bile, a yellow-green fluid that helps digest fats. As bile moves through your intestines, enzymes and bacteria break it down step by step, eventually converting it into stercobilin, the brown pigment you see in a typical bowel movement. Any change that affects bile production, bile flow, or how quickly food moves through your gut can alter that final color.
Green Poop
Green is one of the most common color changes, and it’s almost always harmless. The two main causes are diet and transit time.
Leafy greens like spinach, kale, and broccoli contain chlorophyll, which can tint your stool bright green. Avocados, herbs, matcha, and pistachios can do the same. Even green food dyes in candy or frosting will pass through with their color intact.
The other common cause is diarrhea. Bile starts out yellow-green and only turns brown after bacteria in the large intestine have time to work on it. When food moves through too quickly, bile doesn’t fully break down, and the stool stays green. Some antibiotics can also cause green or yellowish stool, partly by speeding up transit and partly by disrupting the gut bacteria that would normally finish the conversion.
Yellow, Greasy, or Foul-Smelling Poop
Occasional yellow stool isn’t alarming, especially if you’ve been eating a lot of sweet potatoes, carrots, or turmeric. But if your stool is consistently yellow, greasy, bulky, foamy, or unusually foul-smelling, that pattern points to fat malabsorption: your digestive system isn’t breaking down and absorbing fats properly, so they’re being excreted instead.
This type of stool, called steatorrhea, often floats and can be hard to flush. It tends to look pale or clay-like and may leave an oily residue. The underlying causes range widely. Celiac disease, Crohn’s disease, and chronic pancreatitis are among the more common ones. Gallstone-related pancreatic problems, cystic fibrosis, small intestinal bacterial overgrowth (SIBO), and even certain parasitic infections like giardia can also be responsible. If greasy, pale yellow stools persist for more than a few days, it’s worth getting checked out.
Pale, Clay-Colored, or White Poop
This is one of the colors that deserves prompt attention. Stool gets its brown color from bilirubin in bile. When bile isn’t being produced or can’t reach your intestines, the result is stool that looks white, gray, or light tan.
The most common cause is a problem somewhere in the biliary system: the liver, gallbladder, or bile ducts. Gallstones can block bile flow. Hepatitis (whether viral, toxic, or alcohol-related) can impair the liver’s ability to produce bile. Cirrhosis, fatty liver disease, narrowing of the bile ducts, and tumors affecting the liver, bile ducts, gallbladder, or pancreas can all produce pale stool. Pancreatitis is another possibility.
If you notice clay-colored stool along with yellowing of your skin or eyes (jaundice) and dark urine, that combination suggests bile is backing up into your bloodstream rather than reaching your gut. That warrants a call to your doctor right away rather than a wait-and-see approach.
Black Poop
Black stool has two very different explanations, and telling them apart matters.
The harmless version comes from foods and supplements. Iron supplements commonly turn stool dark green to black. Pepto-Bismol and other bismuth-containing medications turn it jet black. Black licorice, blueberries (especially in large quantities), blood sausage, and activated charcoal can all do the same. If you can trace the color to something you ate or took, there’s generally nothing to worry about.
The concerning version is called melena: black, tarry stool with a distinctly foul smell. This signals bleeding in the upper digestive tract, typically the esophagus, stomach, or the first part of the small intestine. Blood that’s been digested turns dark and sticky rather than red. If your stool is black and tarry and you haven’t taken iron, bismuth, or eaten anything that explains it, that’s a situation that needs medical evaluation quickly. A simple chemical test can confirm whether blood is present.
Red or Bloody Poop
Bright red blood in or on your stool usually comes from the lower digestive tract: the colon, rectum, or anus. The most common culprits are hemorrhoids and anal fissures. Hemorrhoids are swollen veins in the rectum or anus, similar to varicose veins. Internal hemorrhoids are typically painless but tend to bleed, often leaving bright red streaks on the stool or toilet paper. External hemorrhoids may cause pain along with bleeding. Anal fissures, small tears in the lining of the anus, cause sharp pain during bowel movements along with a small amount of bright red blood.
Before you assume it’s hemorrhoids, though, consider your diet. Beets contain a red pigment called betanin that can turn stool convincingly blood-red. Cherries, tomatoes, red gelatin, and red food dyes can produce similar results. If you ate any of these in the past day or two, that’s likely your answer.
Persistent red blood that isn’t explained by food, especially if it’s mixed into the stool rather than just on the surface, can signal conditions further up in the colon that need evaluation.
Orange Poop
Orange stool is nearly always dietary. Beta-carotene, the pigment that makes carrots orange, passes through your system and tints your stool along the way. Sweet potatoes, squash, pumpkin, and other orange foods have the same effect. Some artificial food colorings can produce orange tones as well. On rare occasions, orange stool can overlap with the early stages of reduced bile flow, appearing as a lighter-than-normal brown, but if it’s clearly orange and you’ve been eating the right foods, it’s almost certainly harmless.
Stool Color in Babies
Infant stool follows its own color rules, and new parents are often caught off guard. A newborn’s first bowel movements, called meconium, are black and tarry. This is completely normal and expected. It’s the buildup of everything the baby ingested in the womb.
After meconium passes, color depends largely on how the baby is fed. Breastfed babies typically produce mustardy yellow stool. Formula-fed babies tend toward yellow-tan with hints of green. Both are normal. Green stool in babies, while startling, is usually just a variation of normal digestion or a sign that food is moving through a bit quickly.
The one color that’s genuinely alarming in infants is the same as in adults: white, pale, or clay-colored stool. In newborns, this can indicate biliary atresia, a condition where the bile ducts are blocked or absent. Pediatricians check for this early, but if you notice persistently pale stool in your baby, it’s worth bringing up immediately.
Foods, Supplements, and Medications at a Glance
- Green: spinach, kale, broccoli, avocados, matcha, pistachios, green food dye, iron supplements, some antibiotics
- Red: beets, cherries, tomatoes, red food dye, red gelatin
- Orange: carrots, sweet potatoes, squash, pumpkin
- Purple or dark blue: grapes, plums, blueberries (can also appear very dark or black in large amounts)
- Black: iron supplements, Pepto-Bismol, activated charcoal, black licorice, blueberries, blood sausage
Most food and supplement-related color changes resolve within a day or two after you stop eating the trigger. If a color change persists beyond that, or if you’re also experiencing pain, weight loss, persistent diarrhea, or fatigue, the cause is more likely to be something beyond diet.