What Does It Mean if You Have Oily Stool?
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Medically reviewed by Kumkum Sarkar Patel, MD
Oily stool, known medically as steatorrhea, indicates there is too much fat in your poop. You may notice you have oily or greasy stool after eating high-fat foods. Oily stool can also be a sign of an underlying condition that needs treatment.
Conditions that cause fat malabsorption, such as celiac disease and cystic fibrosis, often lead to oily, fatty stool. Fat malabsorption means your body isn't properly digesting food or absorbing fats needed to function. Without treatment, fat malabsorption can lead to harmful nutrient deficiencies and physical damage.
Knowing what oily stool looks like and what it can be a symptom of can help you identify it and seek care so that you can get any treatment you might need.
Symptoms
Oily stools are often greasy, bulky, pale, and foul-smelling. It may look like your stool is covered in slimy mucus. Oily stools can look brown, yellow, orange, or like pale clay. Greasy stools can also appear black if there is blood in your poop. After pooping, you may notice the stool floats or sticks to the toilet bowl.
In addition to greasy, smelly poop, you may experience fat malabsorption symptoms like:
Abdominal pain or cramping
Flatulence (gas)
Children who have oily poop from malabsorption may also show signs of restricted growth and delayed puberty. In severe cases of malabsorption, children can lose fat and muscle mass.
What Causes Oily Stool?
Oily stool is a strong indicator your digestive system isn't breaking down fat and absorbing it correctly. Sometimes, eating a greater amount of high-fat, processed foods can suddenly cause greasy poop that goes away after a day or so. However, long-term oily stool is usually a sign of an intestinal, pancreatic, or bile duct condition that has led to malabsorption.
1.High-Fat Foods
You may notice oily stools after eating a large high-fat meal or snack. Since your digestive tract can't absorb the excess fat it doesn't need, any leftover fat exits in your poop. This effect is typically short-term and goes away after eating food with less fat.
Some high-fat foods that may lead to oily stool include:
Deep-fried foods
Processed snack foods, like chips
Baked goods, like cookies and cakes
Fatty fish, like salmon
Coconut and palm oils
Butter, margarine, or shortening
Vegetable oils, like canola or olive oil
2.Intestinal Malabsorption Disorders
Conditions that affect how your intestines absorb fat and other nutrients can lead to malabsorption. As a result, you may have more fat in your poop.
Intestinal conditions that can cause malabsorption and lead to oily poop include:
Celiac disease: This autoimmune condition causes the body to attack the small intestine after you eat gluten—a protein in wheat, barley, and rye products. Over time, intestinal damage can affect fat absorption, leading to fatty and oily poop. Abdominal pain, bloating, gas, constipation, and diarrhea are also common celiac disease symptoms.
Small intestinal bacterial overgrowth (SIBO): An overgrowth of gut bacteria in the small intestine can alter how the intestines absorb fat, leading to oily stool. You may also experience diarrhea, constipation, gas, and bloating.
Crohn's disease: This inflammatory bowel disease causes digestive tract inflammation. Inflammation and intestinal damage can make fat absorption difficult, resulting in oily stool. You may also experience bloody poop, abdominal pain, and unexpected weight loss.
Whipple disease: This rare bacterial infection affects the gastrointestinal system and how the body processes fat. It can also affect how the eyes, brain, heart, joints, and lungs work. Other symptoms include abdominal pain, weight loss, fever, fatigue, and sore joints.
Tropical sprue: This condition is caused by having too much bacteria in the intestines and is linked to living or visiting tropical areas for extended periods. The infection damages the small intestines lining, making it difficult to absorb fats. As a result, you may have excess fat in your poop that makes it oily and loose. Diarrhea and weight loss are other signs of tropical sprue.
Giardiasis: This intestinal tract infection is caused by ingesting food or water contaminated with Giardia parasite cysts. The parasites live in the intestines and prevent proper fat absorption. As a result, you may have foul-smelling and oily poop, diarrhea, cramps, abdominal pain, nausea, and dehydration.
3.Exocrine Pancreatic Insufficiency (EPI)
People with EPI have a pancreas that doesn't make enough digestive enzymes to help break down fat and aid digestion. As a result, excess fat that isn't digested or absorbed exits in your stool.
A few pancreatic conditions can lead to EPI and its oily stool include:
Pancreatitis: This is inflammation of the pancreas. When the pancreas is inflamed, it can't produce enzymes needed to break down fats. The undigested fats leads to pale, oily stool. You may also experience nausea, vomiting, and severe abdominal pain.
Cystic fibrosis: This genetic disorder causes thick mucus to block tubes going into the pancreas, liver, lungs, and sinuses. Built-up mucus in the pancreas prevents digestive enzymes from absorbing fat, leading to malabsorption and pale, oily stool. Breathing issues and repeat lung infections are also common cystic fibrosis symptoms.
Pancreatic cancer: Cancer can affect the pancreas' function, including its ability to make enzymes that break down fat. As a result, stool can contain too much fat and appear greasy. Other symptoms of pancreatic cancer can include back pain, yellowing of the skin and eyes (jaundice), diarrhea, nausea, and weight loss.
4.Bile Acid Deficiency
Oily stool can be caused by a bile salt deficiency from an underlying liver or bile duct condition. Bile is produced by your liver and carried through small tubes called bile ducts to help break down fats during digestion. When bile flow is reduced or stopped—an occurrence known as cholestasis—the bile can't properly break down fat. As a result, excess fat exiting the body can make your stool oily.
If your bile production has slowed or stopped, oily poop is typically very pale because a pigment in bile called bilirubin also isn't produced properly. Bilirubin gives digestive fluid a yellow color. When this pigment is not made properly in bile, it exits in your stool and gives poop a pale yellow or clay color.
Liver and bile duct conditions that can cause bile acid deficiency and oily stools include:
Acute hepatitis: Hepatitis viruses A, B, C, D, and E can cause short-term liver inflammation, known as acute hepatitis. This viral infection can affect liver function enough to cause cholestasis and oily, pale stool. Jaundice, fever, fatigue, nausea, and joint pain are common.
Cirrhosis: This is a scarring of the liver that can make liver function difficult. In turn, cirrhosis can cause cholestasis and pale, oily stools. Other symptoms can include itchy skin, jaundice, nausea, fatigue, and an easiness to bleed or bruise.
Primary sclerosing cholangitis: This liver disease causes inflamed and scarred bile ducts inside and outside the liver. Narrowed and blocked bile ducts allow bile to build up and damage the liver. As a result, bile isn't available to break down fats, causing oily, pale stools.
Primary biliary cholangitis: This liver disease causes inflamed and scarred bile ducts inside the liver, resulting in decreased bile movement out of the liver. Eventually, bile ducts may collapse. As a result, reduced bile production leads to oily, pale poop.
Gallstones: These stone-like pieces of bile can block your bile ducts that carry bile from the liver, gallbladder, and small intestine. This blockage can cause bile salt levels to drop, resulting in fat malabsorption and oily, yellow poop. Gallstones often cause intense abdominal pain, nausea, vomiting, fever, and jaundice.
5.Medication
Lipase inhibitors like orlistat (sold under brand names like Alli and Xenical) are weight loss medications that can increase the fat content in your stool.
To help you lose or maintain weight, orlistat prevents your digestive tract from absorbing some fat from food. The unabsorbed fat then leaves in your stool. As a result, you may notice more loose, oily stools after taking the medication.
How Is Oily Stool Diagnosed?
To help diagnose the cause of your oily stool, a healthcare provider will likely ask about your symptoms and review your medical history. From there, they may order diagnostic tests, including:
Quantitative fecal test (72-hour fecal fat test): To help diagnose fat malabsorption, several stool samples are collected over 72 hours after you've followed a diet with a specific amount of fat. Fat content that exceeds 7 grams after 24 hours means the body isn't absorbing fat correctly.
Stool elastase test: This test helps diagnose EPI. One stool sample is collected and analyzed for elastase, a digestive enzyme the pancreas produces. If little or no elastase is found in stool, it means your pancreas isn't making enough elastase to break down fat and aid digestion.
D-xylose test: To help see how the intestines absorb nutrients, you'll drink 8 ounces of water with a simple sugar (D-xylose). Urine samples are then taken over the next five hours, and a blood sample may be taken at the first and third hour. You may have a malabsorption issue if D-xylose isn't found in the urine or blood samples.
Blood tests: Testing blood samples for transglutaminase IgA antibodies (TTG-IgA) can help diagnose celiac disease. Blood tests can also help diagnose cholestasis and viruses.
Endoscopic retrograde cholangiopancreatography (ERCP): To help identify abnormal bile ducts that lead to cholestasis, a flexible tube with a light and camera (endoscope) is inserted into the bile ducts.
Magnetic resonance cholangiography (MRC): This magnetic resonance imaging (MRI) device uses magnetic fields and radio waves to take internal images of the liver, gallbladder, bile ducts, and pancreas. This can help identify abnormalities that may lead to cholestasis and EPI.
Non-invasive breath tests: To help diagnose bacterial overgrowth that leads to SIBO, you'll drink a sugary drink and then periodically breathe into a device. If you have bacterial overgrowth in your intestines, the bacteria will interact with the sugar and release hydrogen and methane. Higher levels of hydrogen or methane in your breath tests can indicate you have bacterial overgrowth in the intestines. However, the tests are often inaccurate.
Additional non-invasive imaging tests like abdominal ultrasound or computed tomography (CT) can look inside the body to identify liver and bile duct abnormalities. In some cases, a liver or intestinal biopsy may also be necessary. For a biopsy, a tissue sample is taken and reviewed under a microscope for abnormalities like scarring, bacteria, and cancer.
Treatments for Oily Stool
Treating oily stool depends on the underlying cause. If your oily stool is caused by dietary issues, you can often treat it by changing your diet. This may include limiting alcohol or following a gluten-free diet.
Other conditions may need medication to manage fat malabsorption. For instance, EPI is typically treated with pancreatic enzyme replacement therapy (PERT). PERT involves taking medicine that contains pancreatic enzymes so you can restore enzymes needed for fat absorption.
People with EPI may also be instructed to follow a high-fat diet and take fat-soluble vitamins like vitamins A, K, and D. This may seem counterintuitive if fat isn't absorbed well, but high-fat diets can help restore levels of other nutrients that aren't getting well-absorbed. Oily stool, pain, and lung disease caused by cystic fibrosis may also be managed with a high-fat diet and enzyme replacement.
If you have chronic pancreatitis, a low-fat diet may help minimize oily stools when taken with pancreatic enzymes. SIBO and bacterial infections are often treated with antibiotics.
Complications of Oily Stool
The oily stool itself may not cause complications, but the malabsorption issues that cause the stools can lead to nutrient deficiencies and malnutrition. If your body doesn't get the nutrients it needs, it can't function properly. Complications of malabsorption include:
Fat-soluble nutrient deficiencies (vitamins A, D, E, and K)
Zinc deficiency
Sudden weight loss
Increased risk of infections
Poor neurological development in children
Stunted growth in children
Increased risk of low bone density (osteopenia), bone fractures, and loss of bone mass (osteoporosis)
When To See a Healthcare Provider
If oily stool doesn't go away after a few days, contact your healthcare provider. Persistent steatorrhea is usually a sign of a condition that needs treatment.
Signs you may have a complication related to oily stools and fat malabsorption include:
Dehydration
Unexpected weight loss
Muscle weakness or pain
Fatigue
Jaundice
Easily bruise or bleed
Itchy skin
Fever
Stunted growth in children
Bloody stool
Severe abdominal pain
How To Prevent Oily Stool
Maintaining a healthy gut can help promote proper food absorption and digestion. Some ways to help prevent oily stool include:
Avoiding foods with gluten if you have celiac disease
Limiting high-fat, processed, and deep-fried foods
Limiting alcohol intake, especially if you have a liver condition
Managing stress with activities like yoga, exercise, or meditation
A Quick Review
Oily stool, or steatorrhea, means there is excess fat in your poop. Oily stool is usually caused by fat malabsorption due to diet or an underlying health condition. High-fat foods, intestinal malabsorption conditions, exocrine pancreatic insufficiency, bile acid deficiency, and certain medications can affect how the body absorbs fat. If fat continues to be poorly absorbed and is instead released with your stool, you can develop harmful nutrient deficiencies. If you have oily stool that doesn't resolve on its own, see your healthcare provider to determine whether you have a condition that needs treatment.
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