The color of your poop is primarily determined by bile, a digestive fluid your liver produces. Bile contains a pigment called bilirubin, and as it travels through your digestive tract and gets broken down by bacteria, it turns your stool its typical brown color. When something disrupts that process, or when foods and medications add their own pigments to the mix, your stool changes color. Most color changes are harmless, but a few are worth paying attention to.
Why Brown Is Normal
Your liver releases bile salts into your digestive tract to help break down fats. As bile moves through your intestines, bacteria chemically transform its green pigment into brown. The longer bile spends in your gut, the browner it becomes. This is why healthy stool is some shade of brown, from light tan to dark walnut. Variations within that range are completely normal and can shift day to day based on what you eat and how quickly food moves through you.
Green Stool
Green poop has two common explanations. The first is diet. Chlorophyll, the pigment that makes plants green, can do the same to your stool. Broccoli, kale, spinach, and other leafy greens are the usual culprits. Green food dyes in candies, ice cream, or drinks can have the same effect.
The second explanation is speed. When food moves through your intestines faster than usual, bile doesn’t have enough time to fully break down from green to brown. This rapid transit can happen with diarrhea from a stomach bug, food poisoning, or infections like salmonella, E. coli, norovirus, or the parasite Giardia. If your green stool comes with diarrhea, fever, or cramping that lasts more than a couple of days, it’s worth getting checked out.
Red Stool
Red stool looks alarming, but food is often the cause. Beets are the most common offender. Their red-purple pigments (betalains) aren’t consistently broken down during digestion, so they can pass through relatively unchanged and tint your stool anywhere from pinkish to deep red. How well your body handles betalains varies from person to person. Cranberries and blueberries contain similar pigments and can have the same effect.
Tomatoes, watermelon, and other lycopene-rich foods can also turn stool red, though you’d typically need to consume a large amount, like a big bowl of tomato soup or a lot of fresh salsa. Red food dyes, particularly Red 40 (common in candy, sugary cereals, chips, and gelatin desserts), are another frequent cause.
Red stool that isn’t explained by something you recently ate may contain blood from the lower digestive tract. Hemorrhoids are the most common source and usually produce bright red streaks on the stool or toilet paper. Other possible causes include Crohn’s disease, ulcerative colitis, colon polyps, and bacterial infections like E. coli or salmonella. Capsaicin from hot peppers can irritate the lining of the rectum enough to cause light bleeding as well. If you see red and can’t trace it to a food, or if it happens repeatedly, it’s a signal to get evaluated.
Black Stool
Black stool falls into two very different categories, and telling them apart matters.
The harmless kind is stool that’s simply been stained dark by something you ingested. Iron supplements are a common cause. So are bismuth-based medications like Pepto-Bismol, activated charcoal, black licorice, blueberries, and blood sausage. This type of black stool looks dark but otherwise has a normal consistency and smell.
The concerning kind is called melena. It looks jet black, has a tarry or sticky consistency, and has a distinctly strong, foul odor that’s noticeably different from regular stool. That smell comes from blood being digested as it travels through the entire length of your GI tract. Melena typically signals bleeding somewhere in the upper digestive system, like the stomach or the first part of the small intestine. The longer the blood travels, the darker and more pungent it becomes. If your black stool is tarry and unusually smelly, and you’re not taking iron or bismuth medications, treat it as urgent.
Pale, White, or Clay-Colored Stool
Since bile is what gives stool its brown color, pale or clay-colored stool means bile isn’t reaching your intestines. This is one of the stool colors that almost always warrants medical attention because it points to a problem with your liver, gallbladder, or bile ducts. Gallstones blocking the bile duct, liver disease, and pancreatic conditions can all reduce or stop bile flow. The result is stool that looks grayish-white, like clay or putty. An occasional lighter-than-usual stool isn’t necessarily cause for concern, but consistently pale or white stool is a clear signal that something is blocking bile from doing its job.
Yellow, Greasy Stool
Yellow stool that looks oily, floats, and is difficult to flush usually means your body isn’t properly digesting fats. Digesting fat requires teamwork between your small intestine, your pancreas (which supplies digestive enzymes), and your liver (which supplies bile). When any part of that chain breaks down, undigested fat passes into your stool and gives it a yellow, greasy appearance, sometimes with a particularly bad smell.
Several conditions can cause this. Celiac disease damages the lining of the small intestine and impairs its ability to absorb nutrients, including fat. Chronic pancreatitis, cystic fibrosis, and pancreatic cancer can reduce enzyme production. Crohn’s disease, bacterial overgrowth in the small intestine, and parasitic infections like giardiasis are other possibilities. An occasional yellow stool after a particularly fatty meal is usually nothing to worry about, but if it’s a pattern, especially if you’re also losing weight or feel bloated after eating, it’s worth investigating.
Orange Stool
Orange stool is almost always dietary. Beta-carotene, the pigment in carrots, sweet potatoes, and winter squash, can tint your stool orange when you eat a lot of these foods. Artificial orange food coloring and some supplements do the same thing. In rare cases, orange stool can result from reduced bile reaching the intestines (an early or partial version of the same problem that causes clay-colored stool), but if you’ve been eating orange-colored foods, that’s the most likely explanation.
What Baby Poop Colors Mean
Infant stool follows its own color rules, especially in the first weeks of life. Newborns pass meconium in their first few bowel movements, a thick, black, tarry substance that looks alarming but is completely normal. It’s made up of materials the baby ingested in the womb.
Once meconium clears, breastfed babies typically produce mustardy yellow stool, often with a seedy texture. Formula-fed babies tend toward yellow-tan with hints of green. After this transition, all shades of yellow, brown, and green are considered normal in infants. The colors to watch for in babies are the same ones that are concerning in adults: white or clay-colored (suggesting a bile problem), red (possible blood), and black stool after the meconium phase has passed.
How Doctors Test Stool Color Changes
If a color change has you worried, your doctor can run a simple test to check whether blood is actually present, even in amounts too small to see. The most common version is called a fecal immunochemical test (FIT), which requires just a single stool sample and no special dietary preparation beforehand. An older version, the guaiac test, uses a plant-based chemical to detect blood but requires samples from three separate bowel movements and may require you to avoid certain foods and medications beforehand. FIT has largely replaced it because it’s more sensitive and more convenient. Either test can give you a definitive answer about whether the color you’re seeing is blood or just last night’s beet salad.