Normal poop is some shade of brown, ranging from light tan to dark chocolate. That color comes from a pigment your body produces when it breaks down old red blood cells. Your liver sends this pigment into your digestive tract through bile, and bacteria in your colon chemically transform it into compounds that oxidize to a brownish-yellow. Any shade within that brown spectrum is healthy and unremarkable.
But stool can show up in almost every color, and while most shifts are harmless and diet-related, a few are genuine warning signs. Here’s what each color actually means.
Green Stool
Green is one of the most common color changes, and it’s almost always harmless. Bile starts out green when your liver releases it. As it travels through your intestines, enzymes chemically alter it, gradually shifting the color from green to brown. If food moves through your large intestine faster than usual, like during a bout of diarrhea, bile doesn’t have time to fully break down. The result is green stool.
Leafy greens like spinach and kale can also turn stool green, as can green food coloring, matcha, and iron-rich supplements. If you recently ate a big salad or had a stomach bug with loose stools, green poop is the expected outcome. It typically resolves on its own once your digestion normalizes or you change your diet.
Yellow, Greasy, or Foul-Smelling Stool
An occasional yellow stool isn’t concerning, especially if you’ve been eating foods with yellow coloring like turmeric. But stool that is consistently yellow, oily, and unusually foul-smelling points to fat malabsorption. The clinical term is steatorrhea, and it means your body is failing to absorb dietary fat properly. Normally, your digestive system absorbs over 92% of the fat you eat. When that process breaks down, undigested fat passes into your stool, giving it a pale yellow color, a greasy sheen, and a tendency to float.
Several conditions can cause this. Celiac disease damages the lining of the small intestine and impairs fat absorption. Chronic pancreatitis and cystic fibrosis reduce the enzymes your pancreas produces to digest fat. Parasitic infections like giardia can also interfere with absorption. If you’re seeing persistently yellow, greasy stools, that pattern is worth investigating, not ignoring.
Orange Stool
Orange poop is usually a food story. Beta carotene, the pigment that makes carrots, sweet potatoes, and winter squash orange, passes through your digestive system and tints your stool the same color. Eating a lot of these foods, taking beta carotene supplements, or consuming foods with orange dye (like orange soda or cheese-flavored snacks) can all produce orange stools.
A few medications also cause it. The antibiotic rifampin is well known for turning body fluids orange, stool included. Some aluminum hydroxide antacids can produce orange or gray stool. If you can trace the color to something you ate or a medication you’re taking, it’s not a concern.
Black Stool
Black stool has two very different explanations, and telling them apart matters. The harmless version comes from iron supplements, bismuth-containing medications like Pepto-Bismol, activated charcoal, black licorice, or blueberries. These produce a dark or black stool that looks normal in texture.
The concerning version is called melena: stool that is jet black, sticky, and tar-like. Melena signals bleeding in the upper digestive tract, typically the stomach or the first part of the small intestine. Blood that travels through the full length of the digestive system gets chemically altered along the way, turning it black rather than red. Peptic ulcers are the most common cause. Other possibilities include inflammation of the stomach lining (often related to heavy alcohol use or regular use of aspirin and anti-inflammatory painkillers), tears in the esophagus, and, less commonly, tumors.
The key distinction is texture. If your stool is black but formed normally and you’re taking iron or bismuth, that’s expected. If it’s black, tarry, and sticky, with a distinctive foul smell, that’s a different situation entirely. About 90% of significant GI bleeding originates above the small intestine, and melena is the most common way it shows up.
Red or Bloody Stool
Before assuming the worst, think about what you recently ate. Beets are the classic culprit: they can turn stool (and urine) a startling shade of red. Tomatoes, blackberries, and red food coloring can all create a similar appearance.
If food isn’t the explanation, red or maroon stool suggests bleeding in the lower digestive tract, typically the colon or rectum. Common causes include hemorrhoids, anal fissures, diverticular disease, inflammatory bowel disease, and polyps. Hemorrhoids and fissures tend to produce bright red blood on the surface of the stool or on toilet paper. Bleeding from higher in the colon often mixes more thoroughly with the stool, producing a darker, maroon color.
Any persistent red blood in your stool that you can’t explain with food deserves medical attention, even if you suspect hemorrhoids. A doctor can determine the source with a physical exam and, if needed, a scope procedure to look at the lining of your lower colon.
White, Gray, or Clay-Colored Stool
This is the color change that should always prompt a call to your doctor. Pale, clay-colored, or chalky white stool means bile isn’t reaching your intestines. Since bile pigments are what give stool its brown color, their absence produces something that looks like wet clay or putty.
The most common reason bile gets blocked is gallstones lodged in the bile duct. Other causes include tumors pressing on or growing within the bile ducts (such as pancreatic head cancer or bile duct cancer), scarring of the bile ducts from inflammatory conditions, and severe liver diseases like hepatitis or cirrhosis that impair bile production altogether. Some of these conditions are serious and progressive, which is why pale stool is not a “wait and see” symptom. It often comes with other signs like dark urine, yellowing of the skin or eyes, and abdominal pain, but the stool color change alone is enough reason to get evaluated.
What’s Normal for Babies
Infant stool follows its own color rules, and new parents often worry unnecessarily. A newborn’s first poop, called meconium, is blackish-green, thick, and sticky, almost like tar. This is normal. It’s made up of everything the baby swallowed in the womb: amniotic fluid, skin cells, and mucus. Most babies pass meconium within 24 to 48 hours of birth.
Once a baby starts feeding on breast milk or formula, the stool transitions over a few days. Breastfed babies typically produce mustard-yellow, seedy, loose stools. Formula-fed babies tend toward tan or yellowish-brown with a firmer consistency. Green stools in infants are common and usually harmless, often caused by foremilk-hindmilk imbalance during breastfeeding or iron-fortified formula.
The colors that are concerning in babies are the same ones concerning in adults: white or clay-colored stool (which can signal biliary atresia, a serious newborn liver condition), red stool not explained by food, and black stool after the meconium phase has passed.
How Long a Color Change Should Last
Diet-related color changes typically resolve within one to two days after you stop eating the responsible food. Medication-related changes (from iron, bismuth, or antibiotics) last as long as you’re taking the medication and clear within a few days of stopping.
A color change that persists for more than two to three bowel movements without an obvious dietary or medication explanation is worth paying attention to. If it’s accompanied by abdominal pain, unexplained weight loss, changes in stool consistency, or visible blood, those combinations move the urgency up considerably. The stool colors that warrant prompt medical evaluation regardless of other symptoms are black and tarry, bright red without a food explanation, and white or clay-colored.