Stool color is one of the few things about your body you see every day, so a change tends to register. Texture, how long it lasts, and what comes with it are what put it in context.
Most color changes trace back to a meal, a supplement, or a medicine. Others reflect how fast stool is moving through, or something happening in the gut.
Most shifts are dietary and pass on their own. Red, black, and persistently pale stool are the ones that earn a closer look.
What Gives Stool Its Color
Bilirubin is the yellow-orange pigment left over when the body breaks down old red blood cells. The liver sends it into the small intestine in bile. In the colon, gut bacteria reduce it to urobilinogen, which goes on to form stercobilin, the pigment that makes stool brown.
That conversion takes time, so poop color also depends on how fast stool moves through, and on any pigment from food, supplements, or medicine riding along with it.
When less bilirubin reaches the intestine, less brown pigment forms and stool becomes paler. A few medicines can also lighten stool, and food pigments do not usually explain it, which is why persistently pale stool warrants more attention than most food-related changes.
Stool Color Chart: Common Causes and What Else They Can Mean
Most colors have an ordinary explanation. Pale, red, and black are the ones that can also point to something medical.
|
Color or appearance |
Common explanation |
What else it can mean |
|---|---|---|
|
Brown, any shade |
Normal bile pigments |
Within the normal range; color alone says little |
|
Green |
Leafy greens, green dye, iron, faster transit |
Diarrhea, when it persists or comes with fever, blood, or signs of dehydration |
|
Clear or watery |
A laxative or colonoscopy prep, or watery diarrhea |
Dehydration, if watery diarrhea continues |
|
Clear or whitish mucus |
Small amounts are normal, from the bowel lining |
Increased or bloody mucus needs a doctor's assessment |
|
Orange |
Carrots, sweet potato, squash, beta-carotene |
If it looks washed out or chalky, read it as pale stool |
|
Blue or purple |
Food dyes and blue-coated medicines; beets, red cabbage, grape juice |
Deep purple shading toward red gets the same check as bright red |
|
Yellow, greasy, floating |
Diet and faster transit |
Fat that is not being absorbed, especially if greasy, bulky, and persistent |
|
Pale, clay, gray, or white |
Reduced bile pigment; some medicines can contribute |
A blocked bile duct, or other liver and bile problems |
|
Bright red |
Beets, tomato, red food coloring |
Bleeding, most often lower down, though not always |
|
Dark red or maroon |
Beets, red food coloring |
Bleeding; the shade does not reliably indicate the source |
|
Black |
Iron, bismuth, licorice, blueberries |
Possible bleeding in the upper digestive tract |
Children and newborns in particular run on a different baseline and have their own section below.
Why Is Stool Green?
Green stool is usually harmless, and food pigments, iron, and faster transit explain the common cases.
Food and dye. Spinach, kale, pesto, and green food coloring carry enough pigment through the gut to tint what comes out.
Iron supplements. Iron darkens stool, sometimes toward green and sometimes toward black.
Speed. Bile is green before bacteria finish converting its pigment. Diarrhea moves stool through too quickly for that conversion to finish.
Fever, blood in the stool, or signs of dehydration are reasons to call a doctor, whatever the color. So is diarrhea that keeps going.
Related reading: Why Is My Poop Green?
Clear, Watery, and Mucus Poop
Liquid stool, watery diarrhea, and mucus can look alike in the toilet and have different explanations.
After a laxative or colonoscopy prep, bowel movements can run mostly liquid as solid material clears. Watery diarrhea does the same during an intestinal illness.
If it keeps going, the risk is fluid loss. Dark urine, dizziness on standing, a dry mouth, or passing much less urine than usual are the signs to act on, and they matter more than the clarity.
The bowel lining produces mucus so stool passes without scraping, and small amounts of clear or whitish mucus can be normal. Increased mucus, mucus with blood, or mucus alongside cramping and a lasting change in bowel habits should be raised with a doctor.
Related reading: Clear Poop: Why It Happens and When to Pay Attention
Orange Stool
Orange stool often follows foods rich in beta-carotene: carrots, sweet potato, squash, and pumpkin. Some supplements do it too.
Light orange that looks washed out or chalky rather than vivid should be read as pale stool, covered further down.
Blue and Purple Stool
Blue usually traces to something you ate, whether a dye in food or a coating on a medicine.
Blue. Icing, sports drinks, and blue raspberry candy are the usual sources.
Purple. Beets, red cabbage, and grape juice can leave stool purple or reddish. Deep purple shading toward red gets the same check as bright red, since food and blood can both produce it.
Researchers have used blue dye as a measuring tool. In a 2021 study, 863 healthy adults ate blue-dyed muffins and timed how long until blue appeared, as a way of measuring gut transit. It is a research method, not something an individual can read anything into.
Yellow, Greasy, or Foul-Smelling Stool
Persistent yellow stool is more concerning when it is also greasy, bulky, or floating than when the color changes alone.
Steatorrhea is the passage of excess fat in stool. It produces bulky, oily, foul-smelling stools that float and are hard to flush.
Celiac disease and exocrine pancreatic insufficiency are among the causes, as is tropical sprue in people who have lived or traveled in the tropics.
An isolated greasy stool after a rich meal is a different matter from a persistent pattern. Greasy, floating stools that persist over weeks, particularly alongside weight loss or bloating, should be raised with a doctor, who can test for malabsorption rather than guess at it.
Related reading: Yellow Poop: Common Causes and When to Call Your Doctor
Pale, Clay-Colored, and Gray Stool
Pale, clay-colored, gray, and white can all describe stool that has lost its normal brown pigment, and that is worth taking seriously.
When bilirubin cannot reach the intestine, the brown pigment never forms. Biliary obstruction often presents as jaundice with clay-colored stool and dark urine. Not everyone has all three, and the absence of jaundice does not settle the question.
MedlinePlus lists gallstones, viral and alcoholic hepatitis, narrowed bile ducts, and tumors of the liver, bile system, or pancreas among the possible causes. Some medicines can contribute too.
The bilirubin that cannot leave that way builds up in the blood instead, which is what causes jaundice and dark urine.
MedlinePlus advises contacting a provider if stool is not the normal brown color for several days, and sooner if jaundice or dark urine comes with it. What gets ordered depends on the exam: it may involve liver blood tests and imaging of the liver and bile ducts.
Related reading: Pale or Clay-Colored Stool: Diet, Meds, or Your Liver?
Why Is Stool Bright Red?
Red usually comes down to food pigment or blood, and the two look similar enough that appearance alone does not separate them.
Beets, tomato, and foods with red coloring can make stool look reddish. A doctor can check whether blood is present, because appearance cannot settle it.
Fresh red blood most often comes from the lower digestive tract, closer to the rectum and anus, because it has not had the time or distance to darken.
That is a tendency, not a rule. In a 1999 study of 312 patients with rectal bleeding who went on to colonoscopy, 217 described bright red blood. Twenty of those had lesions beyond the reach of a sigmoidoscope, including eight cancers.
What any one person needs still depends on age, history, and exam.
Dark Red and Maroon Stool
Maroon is the hardest shade to place, because blood darkens as it travels and color is a poor guide to where it came from.
Very rapid upper bleeding can arrive still red. Blood can also darken during slower transit, even when the bleeding started in the lower colon.
If food does not explain red or maroon stool, have it looked at rather than reading the shade for clues.
Why Is Stool Black?
Black stool has both harmless and serious causes, and the two can look alike.
Melena, the black, tarry stool that comes from bleeding, usually means bleeding in the upper digestive tract, because blood darkens over the distance it travels. Stool can stay black for several days after a bleed has stopped, so the color alone does not tell you whether bleeding is ongoing.
Melena is typically black, tarry, and sticky. Iron and bismuth can produce the same look, which makes texture a clue rather than a test.
Bismuth subsalicylate is the active ingredient in Pepto-Bismol. The darkening it causes is harmless and usually fades within a few days of stopping, and it often darkens the tongue at the same time.
That tongue cue is helpful, but it does not rule out bleeding. A plausible medication explanation and a bleed can coexist. Licorice, blueberries, and iron tablets round out the list.
New black, tarry stool that a food or medicine does not clearly explain needs medical help right away. NIDDK lists black or tarry stool among the symptoms of acute GI bleeding and advises seeking help right away rather than waiting to see what follows. Even when a food or medicine could explain the color, weakness, dizziness, fainting, or vomiting blood needs assessment on its own.
