Stool starts out green , then turns bright yellow as it goes through the digestive tract. It is bile and bacteria that finally turn it brown. Yellow or green stools can indicate stool is passing through the digestive tract too rapidly not giving it a chance to change colour. Bright yellow stools can also indicate not enough bile / bilary obstruction.
The color of stool normally is brown. The reason for the brown color is the presence of bile in the stool. Bile is made by the liver, concentrated and stored in the gallbladder, and secreted into the intestine to aid in the digestion of food. Depending on the amount of bile it contains, the normal stool color can range in color from light yellow to almost black.
Bile secreted from the gallbladder into the intestine is a very dark green liquid made up of many chemicals, one of which is bilirubin. When red blood cells are destroyed naturally in the body, the hemoglobin, a protein inside the red blood cells that carries oxygen, is modified in the liver. The by-product of this process is bilirubin, and the liver secretes the bilirubin into bile.
As the bile travels through the intestines, it can undergo further chemical changes, and its color can also change. For example, if the traveling time through the intestine is too rapid, then bile won’t have the time to go through additional color changes and the stool color may be close to green.
The color of stool can change for other reasons as well. Many changes in stool color may not be of much importance, especially if the change happens once and is not consistent from one stool to the next. Sudden major changes in stool color that persist may suggest an underlying medical problem.
Furthermore, gradual but persistent changes in stool color also can signify medical problems.
Some of the important colors of stool that can signify problems include:
pale, orange, and
Stool Color Changes Causes
Stool color can change for a variety of reasons. Some stool color changes may signify an underlying medical condition, and others may be due to ingestion of food or medications.
Dark Colored Stools
Dark-colored stools may be seen in platelet function disorders, iron deficiency anemia, cirrhosis, colorectal cancer, disseminated intravascular coagulation, peptic ulcer, or stomach cancer. Liver disease may include a yellow tone to the skin and whites of eyes (jaundice) and brownish urine.
Black Tarry, Sticky Stools
Bleeding in the stomach or the intestines can change the color of stool. If bleeding occurs in the stomach or the upper part of the small intestine, the stool may turn black and sticky, described medically as black, tarry stool. Generally, black, tarry stool also is foul-smelling. This change in color and consistency occurs because of chemical reactions to blood within the intestine that are caused by digestive enzymes within the intestines.
Maroon or Red Stools
Red or maroon colored stools can also mean the presence of blood in your stools; in the medical field this condition is called hematochezi.
The difference between this color and the black or tarry color is the location of the bleeding. A red or maroon colored stool usually indicates a fresher blood and therefore lower GI bleeding.
bleeding ulcer – gastritis- esophageal varices – a tear in the esophagus from violent vomiting
Maroon color-all the causes of black color stool –
diverticular bleeding- vascular malformation – intestinal infection (such as bacterial enterocolitis) – inflammatory bowel disease- tumor- colon polyps or colon cancer
Bright red color
all the causes of black or maroon color stool – hemorrhoids- anal fissures (”cracks” in the anal area)
Not all red colored stools are caused by bleeding, as some foods can have the same effect. If you’ve recently consumed red-colored gelatin, popsicles, Kool-Aid, tomato juice, soup and/or beets, you may experience reddish stools
Black Stools (Not Sticky, No Odor)
Other causes of black stool are iron pills or bismuth-containing medications (such as, bismuth subsalicylate or Pepto Bismol). If the stool color is dark because of any of these medications, it is typically not sticky in texture and is not foul-smelling .
Gray or Clay-Colored Stool
Stool can be gray or clay-colored if it contains little or no bile. The pale color may signify a condition (biliary obstruction) where the flow of bile to the intestine is obstructed, such as, obstruction of bile duct from a tumor or stone.
A stool that appears clay in color is often seen in cases of mal-absorption, hepatitis, or gallbladder disorders.
Hepatitis and gallbladder disorders often interrupt the flow of bile out of the liver. This disruption will cause the clay color of the stool. Mal-absorption also disrupts the output of bile by increasing the amount of undigested fat in the stool. Bile is responsible for breaking down stool and making it brown in color. When the production is lowered the stool can appear clay in color.
Stool that is yellow may suggest presence of undigested fat in the stool.
This can happen as a result of diseases of pancreas that reduce delivery of digestive enzymes to the intestines, such as chronic pancreatitis (long standing inflammation and destruction of the pancreas usually due to alcohol abuse) or obstruction of the pancreatic duct that carries the enzymes to the intestines (most commonly due to pancreatic cancer).
The digestive enzymes released from the pancreas and into the intestines are necessary to help digest fat and other components of food (proteins, carbohydrates) in the intestines so that they can be absorbed into the body.
If the pancreas is not delivering enzymes into the intestines, then components of food, especially the fat, can remain undigested and unabsorbed. The stool containing the undigested fat may appear yellowish in color, greasy, and also smell foul.
Stool Color Changes Symptoms
The symptoms associated with changes in the color of stool generally correspond to the underlying cause (although the presence of large amounts of blood alone may lead to diarrhea and possibly cramping). In many instances, there may not be any symptoms associated with changes in the color of stool.
Bleeding from the gastrointestinal tract (esophagus, stomach, small intestine, large intestine) leading to red, maroon, or black tarry stools may be without any symptoms at all or may have accompanying symptoms of
abdominal pain due to the underlying cause of the bleeding, for example, an ulcer;
nausea, vomiting of blood, diarrhea, and cramping due to the presence of blood in the stomach and/or intestines; and
weakness, lightheadedness, and dizziness, due to the loss of blood from the body.
Persistently gray or clay-colored stools suggest some type of obstruction to the flow of bile. Obstruction caused by gallstones usually is associated with pain on the right side of the abdomen. However, cancer of the bile duct or cancer of the head of pancreas, which also can cause obstruction to the flow of bile by pressing on the bile duct, may not be associated with abdominal pain unless the tumor is large. The obstruction to the flow of bile causes backup of bile into the blood resulting in yellowness of skin and eyes that is referred to as jaundice.
Yellow stool as a result of undigested fat also may occur with no symptoms. If present, the most common symptom associated with yellow stool will be abdominal pain as a result of chronic pancreatitis, tumor of the pancreas, or obstruction of the pancreatic duct.
If your stool shows orange coloring, it can usually be attributed to foods or medications that you may be taking. Certain medications with beta-carotene (such as a form of vitamin A) can cause orange coloring of your stool. Antacids which contain aluminum hydroxide can also cause orange stool.
Foods that are high in beta-carotene can have the same orange effect on your stool. These include; carrots, sweet potatoes, kale, spinach, turnip greens, winter squash, collard greens, cilantro and fresh thyme. Lastly any foods that have yellow or orange artificial colorings can also cause orange colored stool.
If you can’t attribute your orange stool with anything you ingested, then it may be caused by a lack of exposure to bile salt. Stool starts out as green, and then turns to a yellow-orange in color before being exposed to bile and bacteria which turns the stool brown.
Low exposure to bile salt can be caused by a couple different factors. First, your transit time is so fast that your stool is being pushed through your digestive system too quickly. This quick movement of stool reduces the exposure to bile salt resulting in orange stool.
The passage of an increased amount of stool. This is frequently considered to be 3 or more stools per day, or excessively watery and unformed stool. Chronic diarrhea occurs when loose or more frequent stools persist for longer than two weeks.
Diarrhea causes can be grouped into several general categories.
Infections – viruses, bacteria, parasites
Toxins – often referred to as ‘food poisoning.’ Toxins may be produced in foods as bacteria grow.
These toxins are responsible for the associated vomiting and diarrhea.
Malabsorption – lactose intolerance, celiac disease (sprue) or gluten malabsorption, cystic fibrosis, cows milk protein intolerance, intolerance to specific foods (beans, fruit, etc.) There are other less frequently encountered causes of malabsorption.
Inflammatory Diseases of the Bowel – Crohn’s disease, ulcerative colitis
Medications – antibiotics, laxatives (especially those containing Magnesium), chemotherapy
Stools that float are generally associated with some degree of malabsorption of foods or excessive flatus/gas. Floating stool is seen is a variety of different situations, the majority being diet-related or in association with episodes of diarrhea caused by an acute gastrointestinal infection. A change in dietary habits can lead to an increase in the amount of gas produced by bacteria in the gastrointestinal tract.
Similarly, acute gastrointestinal infections can result in increased air/gas content from rapid movement of food through the GI tract. One misconception is that floating stools are caused by an increase in the fat content of the stool.
In fact, increased air/gas levels in the stool make it less dense and allow it to float. Another cause of floating stools is malabsorption. More than two weeks of diarrhea with floating stools is often seen in people suffering from malabsorption, a dysfunction in the GI tract that affects the body’s ability to digest and absorb fat and other food. Increased levels of nutrients in the stool (those not absorbed by the GI tract) are supplied to the normal bacteria that live in the gut, which in turn produce more gas. This results in more air/gas- rich stool that floats.
Dietary changes, diarrhea, and malabsorption can cause floating stools. Most causes are benign and will resolve when the infection ends or the bacteria in the GI tract become accustomed to the changes in your diet.
Stools normally have an unpleasant odor, but one that is recognized as fairly common or ‘typical’. Stools that have an extremely bad, out- of-the-ordinary odor may be associated with certain medical conditions.
Foul-smelling stools also have normal causes, most notably diet. Foul smelling stools may occur in conjunction with floating stools.
Extremely foul smelling stools can be due to bacteria overgrowth. Some bacteria produce hydrogen sulfide which has a characteristic rotten egg smell (horrible stench).
It can also be the putrifying debris in the gut. Ammonia smelling stools can be attributed to bacteria overgrowth or nitrogen being insufficiently digested or improperly metabolized.
When food is insufficiently digested, the non-absorbed food can then become food for harmful bacteria, or just putrefy, in the gut. Either of these leads to toxins being released in the body.
Sulfur smell – a few people noted that if they eat more sulfur containing foods and have a yeast problem, the yeast may feed on the sulfur foods and get worse.
These cases also say an increase in yeast with sulfur supplements. Other supplements reported to produce a smell when not absorbed and metabolized well are selenium, glutathione, and SAMe.
Besides smelly stools, a person many have bad body odor and bad breathe even shortly after taking a shower or brushing teeth.
When to Seek Medical Care
Individuals should notify their physician when there is a persistent change in the color of their stool.
Persistent black, tarry stools or red, bloody stools signify intestinal bleeding and need to be evaluated by a physician promptly. Individuals should either notify their primary care doctor or visit an urgent care center or emergency room.
Gray or clay-colored stool and yellow stool also may signify diseases of the pancreas, gallbladder, or the liver. The evaluation of these conditions may warrant careful evaluation by an internist, primary care physician, or a gastroenterologist (a physician specialized in disease of the stomach and the intestines).
Exams and Tests
The evaluation of changes in stool color typically begins with a thorough physical examination and personal medical history. The doctor may ask about intake of alcohol, smoking, and other habits. Family history of any cancers, particularly of the liver or pancreas or bleeding problems may be helpful. A review of medications that may affect the color of stool, including over-the-counter (OTC) medications, also is important. Any changes in bowel habits (constipation, diarrhea, and change in frequency) or any pertinent symptoms (pain with or without eating, nausea, vomiting, weight loss, etc.) can provide valuable clues in evaluating the underlying causes of changes in stool color.
Diagnostic testing to find the cause of changes in stool color typically start with simple blood tests including complete blood count (CBC), chemistries, liver enzymes (comprehensive metabolic panel or CMP or SMA 19), and blood clotting (coagulation). These tests can demonstrate anemia, liver disease, gallbladder disease, or other underlying conditions that may be responsible for the changes in stool color. Pancreatic enzymes–amylase and lipase–also can be measured to determine if pancreatic disease is present.
If bleeding from the stomach or intestines is suspected but the stool is not visibly black, red or maroon, occult blood (a small amount of blood that does not cause the color of stool to change much) can be sought by testing the stool directly for blood with a dye (fecal occult blood test or FOBT). This test relies on a chemical reaction between a solution (called guaiac) and hemoglobin in a sample of stool. In the presence of hemoglobin, the drop of solution will turn the stool sample (smeared onto a special paper which reacts chemically with the solution) blue. This test is part of the recommendation for screening for colon cancer, although in clinical practice, it is often used to determine if any bleeding is occurring in the gastrointestinal system. In addition to the test using guaiac, there is an immunological test for blood in the stool that uses an antibody to hemoglobin to detect the blood.
Methods to evaluate a change in the color of stool are upper gastrointestinal endoscopy (esophago-gastro-duodenoscopy or EGD) and colonoscopy. These tests are done by gastroenterologists to look inside the esophagus and stomach (EGD) and the colon (colonoscopy) with a video camera to detect the source of the bleeding or other abnormality that may explain the change in stool color. If necessary, biopsies can be taken with these techniques.
More advanced endoscopic testing to look for obstruction of the biliary or pancreatic ducts is called an endoscopic retrograde cholangio-pancreatography or ERCP. This test is performed like an EGD except that during the test dye is injected into the bile and pancreatic ducts to look with X-rays for obstruction of the ducts.
Other imaging studies sometimes are necessary in order to find the cause of the change in stool color. Computerized tomography (CT scan) is ordered frequently by physicians if the change in stool color is believed to be related to underlying cancer, pancreatic disease, or obstructive conditions of the bile ducts and gallbladder. Ultrasound of the abdomen is a frequently used, relatively inexpensive and reliable test to evaluate for gallstones or blockage of the gallbladder. Magnetic resonance imaging (MRI) of the abdomen sometimes is done to look more closely at any obstructive disease of the biliary or pancreatic ducts.
Stool Color Changes Treatment
The treatment for changes in stool color depends on the cause. As described earlier, some changes in the color of stool can be due to the color of the ingested food. Other more important medical causes may require simple or extensive medical evaluation and treatment.
Self-Care at Home
As for self care, it is important to recognize whether the change in stool color is persistent, recurrent or transient. Generally, changes in stool color that are transient, for example, once or twice, and then return to normal are not as important as persistent or recurrent changes.
Some of the symptoms associated with changes of stool color also are important to recognize. For example, if the stool is red, maroon or black, signifying bleeding from the intestines, then symptoms of abdominal pain, lightheadedness, or dizziness (from losing too much blood) may prompt someone to seek medical care more urgently.
Medical treatment for change in stool color can vary widely depending on what the cause is.
Some common scenarios include gastrointestinal bleeding resulting in red, maroon, or black looking stool. In most cases, these are dealt with by gastroenterologists either in their office or in a hospital setting. Depending on the patient’s description, physical examination, medical history, and results of diagnostic testing, the doctor may decide to treat with medications for stomach ulcers or inflammation in the stomach or the intestines.
In some situations, a specific treatment may not be available for certain types of bleeding, and the patient may only be asked to stop taking medications that can promote further bleeding (aspirin or nonsteroidal antiinflammatory drugs [NSAIDS]).
Sometimes medications are injected into the sites of the bleeding during endoscopic evaluations to help stop the bleeding. In rare situations where bleeding continues despite aggressive medical care, radiologists may pass catheters through the arteries and inject the smaller arteries that are feeding the site of bleeding with chemicals or beads to reduce the bleeding. Surgery may be required to remove part of the intestine that is the site of bleeding.
Clay-colored or gray stools also are evaluated by gastroenterologists as well as surgeons. If the change in color is caused by a stone obstructing the bile or pancreatic duct, the gastroenterologist sometimes can remove the stone by performing an ERCP. In other cases, surgery may be necessary to remove a stone or a tumor.
Change in stool color can be followed based on the cause and based on recommendation of the treating doctor.
Prevention of change in stool color may be meaningless without knowing the cause. Since stool color can change for a variety of reasons, any preventive measure for the cause may play a role in preventing further changes in stool color.
For example, if the stool is black and tarry because of a bleeding ulcer, then avoiding medications that can cause bleeding, such as aspirin, may be a reasonable preventive measure. Avoiding alcohol can be a preventive measure against yellow stools resulting from undigested fat in stool due to pancreatic disease.
On the other hand, some causes of changes in the color of stool, for instance, cancer of the pancreas, may not be preventable.
The outlook for changes in stool color varies with the underlying cause. For example, many causes of bleeding from the stomach or the intestines are benign, such as ulcers, and generally carry good prognoses while bleeding due to a cancer carries a less favorable diagnosis.
Synonyms and Keywords
stool color, stool color changes, chocolate stool color, yellow stool color, green stool color, change in stool color, pale stool color, normal stool color, gallbladder and stool color, bile and stool color, healthy stool color, drastic sudden change in stool color, grey stool color, red stool color, orange stool color, light brown stool color, black stool color, tarry stools, smelly stools, foul smelling stools, normal stool texture, rectal bleeding, blood in stool, stools with blood
Author and Editor
Author: Saimak T. Nabili, MD, MPH
Editor: Jay W. Marks, MD
REFERENCE: MedicineNet.com. “Stool Color Changes (Black, Red, Maroon, Green, Yellow, Gray, Tarry, Sticky).
The Bristol Stool Scale was developed in the United Kingdom by a small team of gastroenterologists at the University of Bristol. It is designed to be a representative explanation for stools commonly seen in toilet water. In the different categories, the chart explains the correlation between the stool's physical attributes and the length of time the stool remained in the colon.
This scale is useful to anyone who would like to determine the condition of their colon because it is a generic indicator; it is not an absolute diagnostic tool. It is, however, a good indicator of what action you may need to take. Below are the chart and the analysis for your use at home.
» Type 1: Separate hard lumps, like nuts
Typical for acute disbacteriosis. These stools lack a normal amorphous quality, because bacteria are missing and there is nothing to retain water. The lumps are hard and abrasive, the typical diameter ranges from 1 to 2 cm (0.4–0.8”), and they’re painful to pass, because the lumps are hard and scratchy. There is a high likelihood of anorectal bleeding from mechanical laceration of the anal canal. Typical for post-antibiotic treatments and for people attempting fiber-free (low-carb) diets. Flatulence isn’t likely, because fermentation of fiber isn’t taking place
» Type 2: Sausage-like but lumpy
Represents a combination of Type 1 stools impacted into a single mass and lumped together by fiber components and some bacteria. Typical for organic constipation. The diameter is 3 to 4 cm (1.2–1.6”). This type is the most destructive by far because its size is near or exceeds the maximum opening of the anal canal’s aperture (3.5 cm). It’s bound to cause extreme straining during elimination, and most likely to cause anal canal laceration, hemorrhoidal prolapse, or diverticulosis. To attain this form, the stools must be in the colon for at least several weeks instead of the normal 72 hours. Anorectal pain, hemorrhoidal disease, anal fissures, withholding or delaying of defecation, and a history of chronic constipation are the most likely causes. Minor flatulence is probable. A person experiencing these stools is most likely to suffer from irritable bowel syndrome because of continuous pressure of large stools on the intestinal walls. The possibility of obstruction of the small intestine is high, because the large intestine is filled to capacity with stools. Adding supplemental fiber to expel these stools is dangerous, because the expanded fiber has no place to go, and may cause hernia, obstruction, or perforation of the small and large intestine alike.
» Type 3: Like a sausage but with cracks in the surface
This form has all of the characteristics of Type 2 stools, but the transit time is faster, between one and two weeks. Typical for latent constipation. The diameter is 2 to 3.5 cm (0.8–1.4”). Irritable bowel syndrome is likely. Flatulence is minor, because of disbacteriosis. The fact that it hasn’t became as enlarged as Type 2 suggests that the defecations are regular. Straining is required. All of the adverse effects typical for Type 2 stools are likely for type 3, especially the rapid deterioration of hemorrhoidal disease.
» Type 4: Like a sausage or snake, smooth and soft
This form is normal for someone defecating once daily. The diameter is 1 to 2 cm (0.4–0.8”). The larger diameter suggests a longer transit time or a large amount of dietary fiber in the diet.
» Type 5: Soft blobs with clear-cut edges
I consider this form ideal. It is typical for a person who has stools twice or three times daily, after major meals. The diameter is 1 to 1.5 cm (0.4–0.6”).
» Type 6: Fluffy pieces with ragged edges, a mushy stool
This form is close to the margins of comfort in several respects. First, it may be difficult to control the urge, especially when you don’t have immediate access to a bathroom. Second, it is a rather messy affair to manage with toilet paper alone, unless you have access to a flexible shower or bidet. Otherwise, I consider it borderline normal. These kind of stools may suggest a slightly hyperactive colon (fast motility), excess dietary potassium, or sudden dehydration or spike in blood pressure related to stress (both cause the rapid release of water and potassium from blood plasma into the intestinal cavity). It can also indicate a hypersensitive personality prone to stress, too many spices, drinking water with a high mineral content, or the use of osmotic (mineral salts) laxatives.
» Type 7: Watery, no solid pieces
This, of course, is diarrhea, a subject outside the scope of this chapter with just one important and notable exception—so-called paradoxical diarrhea. It’s typical for people (especially young children and infirm or convalescing adults) affected by fecal impaction—a condition that follows or accompanies type 1 stools. During paradoxical diarrhea the liquid contents of the small intestine (up to 1.5–2 liters/quarts daily) have no place to go but down, because the large intestine is stuffed with impacted stools throughout its entire length. Some water gets absorbed, the rest accumulates in the rectum. The reason this type of diarrhea is called paradoxical is not because its nature isn’t known or understood, but because being severely constipated and experiencing diarrhea all at once, is, indeed, a paradoxical situation. Unfortunately, it’s all too common.