Healthy poop is brown. The shade can range from light tan to dark chocolate, and all of those variations are normal. Green also falls within the typical range. Beyond brown and green, most color changes are temporary and caused by something you ate, but a few specific colors signal problems worth paying attention to.
Why Poop Is Brown
The brown color comes from a pigment called stercobilin. Here’s the short version of how it’s made: your liver constantly breaks down old red blood cells, producing a yellow-green substance called bile. Bile gets released into your intestines to help digest fat. As it travels through your digestive tract, bacteria in your colon convert about 80% of that bile pigment into stercobilin, which is brown. The more completely your gut bacteria process the bile, the deeper the brown.
This is why anything that disrupts bile production, bile flow, or transit speed through your intestines can change the color of your stool.
The Full Range of Normal
Brown in any shade is ideal. But if your poop is green, that’s usually normal too. Green stool often means food moved through your intestines a bit faster than usual, so the bile didn’t fully break down into its brown end product. Mild diarrhea, a high-fiber meal, or just natural variation in your digestion can cause this.
A single off-color stool is rarely meaningful. What matters more is a pattern: the same unusual color showing up repeatedly over several days without an obvious dietary explanation.
Foods That Change Stool Color
Diet is the most common reason poop looks unusual, and the color shifts can be dramatic enough to cause a real scare if you’re not expecting them.
- Beets can turn stool a blood-red color that looks alarming but is completely harmless.
- Spinach, kale, and broccoli in large amounts produce bright green stool.
- Blueberries can make poop look bluish, dark green, or almost black.
- Carrots, sweet potatoes, and squash shift stool toward orange.
- Cherries, tomatoes, grapes, and plums can tint stool red or purple.
- Pistachios can turn it green.
- Artificial food coloring (from candy, sports drinks, or frosting) creates unusual shades. Mixed colors can even produce black stool.
If you ate any of these in the last day or two, that’s almost certainly your explanation. The color change passes once the food works through your system.
Medications and Supplements
Iron supplements commonly turn stool dark green or black. This is a normal side effect of unabsorbed iron and not a sign of bleeding.
Bismuth subsalicylate (the active ingredient in Pepto-Bismol) can turn your stool jet black. This happens because bismuth reacts with trace amounts of sulfur in your digestive system, forming a harmless black compound. The effect can linger for several days after you stop taking it. Antibiotics, meanwhile, can shift stool yellow or green by disrupting the gut bacteria responsible for producing that normal brown pigment.
Colors That Signal a Problem
A few stool colors deserve attention because they can indicate something happening inside your body that you can’t feel.
Black and Tarry
If your stool is black, sticky, and has a tar-like consistency, and you haven’t taken iron or bismuth, this can be a sign of bleeding in your upper digestive tract. Blood from your stomach or upper small intestine turns black as it’s digested on its way through. The tarry texture is the key distinction: black stool from food or supplements looks dark but has a normal consistency.
Bright Red
Red stool that isn’t explained by beets, cherries, or tomatoes may indicate bleeding lower in your digestive tract, such as in your large intestine or rectum. Because the blood doesn’t travel far before exiting, it stays red rather than turning black. Hemorrhoids are a common and relatively minor cause, but persistent red stool needs evaluation.
White, Pale, or Clay-Colored
This is the color that doctors take most seriously. Pale or clay-colored stool means bile isn’t reaching your intestines. Since bile is what eventually gets converted into the brown pigment, no bile means no color. This points to a problem in what’s called the biliary system: the network connecting your liver, gallbladder, and pancreas. Possible causes include gallstones blocking the bile duct, liver infections like hepatitis, or growths in the liver or pancreas. Even certain medications can temporarily reduce bile flow. If your stool is consistently pale over more than a day or two, that warrants prompt medical attention.
What the Bristol Stool Chart Covers
You may have seen the Bristol Stool Chart referenced in health articles. It’s worth knowing that this tool focuses entirely on shape and consistency, not color. It classifies stool into seven types based on firmness, from hard pellets to watery liquid, with a smooth, sausage-shaped stool in the middle as the ideal. Color is evaluated separately.
A Quick Reference
- Brown (any shade): Normal and healthy.
- Green: Usually normal. Often related to diet or faster digestion.
- Yellow: Can be normal occasionally. Persistent greasy yellow stool may suggest fat malabsorption.
- Orange: Typically from carrots, sweet potatoes, or similar foods.
- Red: Check your diet first (beets, tomatoes). If unexplained, could indicate lower GI bleeding.
- Black: Check medications and diet first. Tarry black stool without a dietary cause may indicate upper GI bleeding.
- White or clay: Not normal. Suggests bile flow is blocked or reduced.
One unusual stool is rarely a concern. A pattern of abnormal color lasting several days, especially white, black (tarry), or red without a food explanation, is the threshold where investigation becomes important.