Digestive Disorders > Symptoms

What does the color of my stool mean?

Dr. med. Andre Sommer

Dr. med. Andre Sommer

The color of stool is usually related to what we eat. Discoloration is therefore often no cause for concern. However, the stool color may be a first indication of a disease. Below you will find out which stool colors are harmless, and when you should go to the doctor.

Stool color Possible causes Better to go to the doctor?
Red Red beet, red wine, bleeding from the lower digestive tract (gastrointestinal tract) If you suspect blood in the stool, a doctor should be consulted
Black Blueberries, charcoal tablets, iron supplements, blood from the upper gastrointestinal tract If not explained by food or medication, a doctor should be consulted
Dark brown Meat consumption, low fluid intake Usually harmless
Yellow Antibiotics, dairy products, missing bile fluidity, dysfunction of the pancreas Yellowish discoloration of the stool for several weeks should be clarified
Green Spinach, bacterial infection (e.g. by salmonella) If you have diarrhea at the same time, a doctor should be consulted
Orange Carrots Usually harmless

What we eat has a big influence on stool color. Symptoms such as flatulence, irregular bowel movements, and our overall quality of life are also closely related to nutrition.

How does stool get its color?

Stool consists primarily of water. It also contains undigested food remains, intestinal bacteria and rejected cells from the intestinal mucosa. Digestive juices of the pancreas are needed to digest food. Bile is also important. Bile and its degradation products in particular give stool its color.

Bile consists of water, fat-digesting bile salts, and bile pigments. These pigments are composed of the breakdown products of red blood cells. The blood pigment responsible for oxygen transport is called hemoglobin. It is broken down into bilirubin, which has a yellowish-reddish color. Another breakdown product is green biliverdin. When the bile enters the intestine, biliverdin is converted to brown stercobilin, giving the stool its characteristic color.

What can change the color of bowel movements?

The coloration of bowel movements often depends on how much water is contained in the stool and what has been eaten. If its color varies between different shades of brown, this is normal. Conspicuous changes occur when someone eats colored foods such as beets or spinach. Once these foods disappear from the diet, the bowel movement should also return to its typical brown color.

Often, the stool appears dark brown from eating large amounts of meat. This is harmless in most cases. If the stool is dark brown, this may also indicate that not enough fluids are being consumed. In addition to the color, the consistency of the stool can also give a first indication of the origin of a change.

Blood from the esophagus, the stomach, or the small or large intestines can also change the color of the stool. Sometimes blood is also visible directly in the stool. Color changes can also occur if bile does not enter the intestine.

What does red stool mean?

Uniformly red-colored stool can be produced by various foods such as beets or red wine. However, a red color may also be an indication of fresh blood. Blood in the stool should always be clarified by a doctor as it can be a sign of illness.

There may be vascular malformations in the small intestine that cause bleeding. Also, protrusions of the intestinal mucosa, polyps, or tumors in the colon can be a cause of blood in bowel movements. The same applies to diverticular disease; parts of the colon wall become inflamed with this disease.

Chronic inflammatory bowel disease such as Crohn's disease or ulcerative colitis can also lead to bloody diarrhea. Hemorrhoids and tears of the mucous membrane around the anus can also cause blood in the stool. The blood is usually visible in the stool when these causes are present.

What does black stool mean?

Black stool may be caused by certain foods, such as blueberries or red wine. Some medicines, in particular iron and coal supplements, also stain the stool black. Not only the color, but also the consistency of the stool can change; it may be firmer than usual.

Stool that is black in color may also be so-called tar stool or tarry stool. This is usually due to bleeding in the upper digestive tract. If bleeding occurs at this point, the blood comes into contact with stomach acid and turns a black color. A doctor should be consulted in this case, and a gastroscopy will be performed to exclude a stomach ulcer or varicose veins in the esophagus.

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What does yellow stool mean?

Yellow-brown stool color is harmless in most cases. The stool can discolor yellowish in particular, with the consumption of milk, starchy products, and eggs. This is typical, for example, in infants who are breast-fed. This is often referred to as “breastfed stool.”

Yellow stool also often appears in conjunction with diarrhea. There are many reasons for diarrhea: It can be caused by viruses, bacteria, or antibiotics.

However, discolored or clay-yellow stool may be more serious; this may be due to the dysfunction of the gallbladder. If gallstones or a tumor of the pancreas block the gallbladder, gallbladder fluid can no longer enter the intestine. This condition can be associated with jaundice, which can be recognized by the conjunctiva of the eyes and the skin turning yellow. Liver inflammation (hepatitis) can also lead to these symptoms; urine usually turns darker in this case.

If the stool is particularly greasy, if it has an unpleasant odor, or if it floats on the water for a long time, this can be a case of steatorrhea (when a lot of fat is excreted with the feces). Since fats in the diet are split and digested especially by the bile and the digestive juices of the pancreas, it may be that not enough of these fluids are present. This can be remedied with enzymes in capsule form. If the yellow stool persists for several weeks, or if there are abdominal pains or other complaints, this should be clarified by a doctor.

What does gray-white stool mean?

Certain examinations sometimes use X-ray contrast media. This can also lead to an almost white stool color. The color in this case should return to the initial state after a few days.

The lack of bile can lead to gray-white stool: A visit to the doctor is necessary in this case.

What does green stool mean?

Green stool can be caused by the intake of chlorophyll-containing foods. This natural dye is included, for example, in salad or spinach.

Green diarrhea, however, is often due to bacterial infections, most likely due to salmonella. This should be determined by the doctor on the basis of a stool sample. Careful hand hygiene is particularly important in this case as salmonella is easily transmitted. Infants also occasionally have green stools. This is usually harmless.

What does orange stool mean?

Sometimes foods can cause special coloring. For example, a large amount of carrots or squash may result in an orange coloration of the stool. This is not dangerous.

What to do if my stool is discolored?

In general: Almost all colors of the stool can be explained by food or medication. The color should return to a normal brown after a few days. If this does not happen or if blood is seen in the stool, a doctor's visit should not be delayed for long.

The doctor can already gain important clues as to whether it could be a disease based on the color, consistency, and frequency of the stool. A stool sample allows further conclusions to be drawn. In this way, the doctor can determine if there are infections due to bacteria or viruses. In addition, the fat content and the digestive enzymes contained in the stool can be examined, for instance, so the functioning of the pancreas can be checked.

Even hidden, so-called occult blood can be detected by certain tests. Together with a detailed medical history and physical examination, the doctor then decides whether further measures must be taken. Sometimes, an imaging procedure such as computed tomography (CT scan) or colonoscopy is necessary.

In most cases, it is not alarming if the stool briefly assumes a different color. If you notice a change, first consider if it could be related to food. However, care should be taken with blood in the stool. When in doubt, a visit to the doctor can provide clarity.

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Dr. med. Andre Sommer

Dr. med. Andre Sommer

I’m André, a medical doctor from Berlin. Together with a team of medical doctors, nutritionists and data scientists we empower people to understand digestive issues with our app Cara Care.

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