Checking the color of your stool is a very good way to monitor your overall health. Most of the time, stool will be light to dark brown in color. But stool that’s a different color, texture, or consistency, are all signs there’s something different going on in your body.
In many cases, it could be caused by the food you eat or a medication you’re taking. But if your stool is discolored for a few days, or you have other symptoms, it could be a sign of something more serious.
Black, tarry stool or bright red stool could be a sign of blood in the stool. Pale, clay-colored stool can be a sign of a blockage of your bile duct. Contact your doctor if you are concerned about the color of your stool.
Does stool color matter?
"Our stool is a marker of our gut health, but it is also a reflection of what we ate, how we ate, and what medications we may have taken, among many other things!" —Dr. Shria Kumar
Stool that’s darker than your typical brown is quite common. Black stool can be a cause for concern. Black or tarry stool can be a sign of blood in your gastrointestinal (GI) tract.
The main causes of dark stool are:
- Upper gastrointestinal tract bleeding, which can be from an infection, medication, trauma (like a car accident), or lesions of the blood vessels
- Stomach/peptic ulcers that cause bleeding in the esophagus
- Acid reflux that causes bleeding and irritation in the esophagus
- Colon cancer
- Swallowing blood from a mouth injury or a nosebleed
- Large amounts of foods like black licorice
- Iron supplements
- Anti-diarrheal drugs like Pepto-Bismol
Bile is a greenish fluid that helps your body digest fat. Bile travels through the GI tract and changes to brown when it interacts with certain enzymes. If your stool is green, it usually means that you have changed your diet slightly or your food is traveling through the large intestines faster than normal so it doesn’t have enough time to break down and change color.
Green stool may be caused by:
- Diarrhea, since food is moving through your intestines faster
- Green foods like leafy green vegetables
- Foods that have been dyed with green food coloring
- Iron supplements
If your stool is pale in color or white, it usually means that bile isn’t moving through your GI tract. This would mean that there’s an obstruction of the bile duct that isn’t letting the bile flow into the intestine. Sometimes, the color can be from large doses of medications.
The main causes of light-colored stool include:
- Gallstones, or hardened deposits of bile that form in the gallbladder and block your common bile duct
- Pancreatic cancer
- Liver disease
Bright red stool
There are quite a few reasons why your stool can appear bright red in color. It can be from bleeding in the rectum or large intestines, or simply eating certain foods.
Red stool may be a sign of:
- Hemorrhoids or anal fissures, causing lower intestinal tract bleeding.
- Diverticulosis, small outpouchings of the wall of the large intestine that can bleed.
- Colon or rectal tumors.
- Ulcerative colitis, a type of inflammatory bowel disease (IBD) that causes ulcers and inflammation in the GI tract. It can cause bleeding and loose stools.
- Crohn's disease, the other type of IBD, causes inflammation that can be anywhere in the GI tract (mouth, small intestine, large intestine, even outside the GI tract). It also can cause bleeding and loose stools.
- Foods like beets, tomato juice, cherries, or cranberries, though this is usually not accompanied by other symptoms.
If your stool is yellow, or more likely, contains yellow droplets (seen floating on the toilet bowl), it is a sign of fat in the stool. It can also have a bad odor and a greasy texture. You may see noticeable amounts of fat in your stool when it’s not absorbed properly by the body. Yellow stool can be a sign you’re having malabsorption issues—along with other signs like difficulty maintaining or gaining weight.
Yellow stool may be caused by:
- Bacterial, viral, or parasitic infections that may be causing malabsorption. One of the most common is giardiasis (also called giardia infection), caused by a microscopic waterborne parasite.
- Surgery, including removing the gallbladder, bariatric surgery, or for another GI issue (like a structural blockage or tumor) where part of the colon is removed. These can all change fat absorption.
- Stress. The brain can signal distress to the gut, affecting how the gut functions. Stress can cause disruptive changes to how nutrients pass through the digestive system.
- Celiac disease, a gluten intolerance in which eating wheat, barley, or rye damages the small intestines and triggers the production of certain antibodies. These antibodies flatten the small intestines villi—structures crucial to proper nutrient absorption.
- Chronic pancreatitis, or inflammation of the pancreas. The pancreas is responsible for producing enzymes that help digestion. Chronic pancreatitis inhibits this.
- Cystic fibrosis (CF) is a hereditary disease that causes mucus, sweat, and digestive juices to be thick and sticky rather than thin and slippery. They then block ducts, tubes, and passageways in the pancreas, intestines, liver, and gallbladder. It causes poor absorption of fat.
When to call the doctor
You should call your doctor if you have any of the following symptoms that don’t stop.
- Weight loss
- High fever
- Severe pain
- Lightheadedness or dizziness
Should I tell my doctor about unhealthy stool?
"Stool is important to look at. Yes, it’s gross! But knowing whether you are having any color or texture changes in your stool is something your doctor will want to know." —Dr. Kumar
Should I go to the ER for abnormal stool colors?
You should go to the emergency department if you have any of these signs of a more serious problem:
- Black, tarry stools or blood in stool
- Very pale stool
- Weight loss
- High fever
- Severe pain
Should I be worried if my stool changes color?
"One-off changes in stool color is not, in and of itself, an issue. It’s when it signifies something more than a dietary change (by being persistent or accompanied by new issues) that it becomes something to investigate." —Dr. Kumar
Abnormal stool color by itself is not a problem. It’s the underlying cause that may need to be treated. That’s why it’s important to pay attention to your stool color, note any other symptoms (diarrhea, fever) or foods you’ve eaten recently, and talk to your doctor.
- If your stool color has changed because of a change in diet and there are no other symptoms, no treatment is needed.
- If you are bleeding, you may need to go to the hospital, have laboratory and imaging tests, and possibly even a procedure, such as an endoscopy or colonoscopy.
- If you have an infection, you will need laboratory testing and, possibly, medications for the infection.
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