Keeping tabs on any changes in your bowel movements is a good way to stay on top of your overall health. For example, noticing oily stools (also called steatorrhea) can sometimes be a sign of an underlying condition.
What Is Oily Stool (Steatorrhea)?
Oily stool is exactly what it sounds like: poop that appears oily or greasy.
Possible causes of oily stool include conditions that lead to exocrine pancreatic insufficiency (EPI), bile acid deficiency states, and diseases that affect the small intestine.
Speaking with a doctor or healthcare provider is highly recommended if you’re noticing excess oil or fat in your stool, especially if you’re experiencing any additional symptoms such as foul-smelling stool, floating stools, diarrhea, weight loss, or severe abdominal pain.
Causes of Oily Stool
There are several possible causes of oily stool, some of which can be serious.
In many cases, having oily stools can signal that your body isn’t absorbing or breaking down fats properly, which can be caused by malabsorption or other medical conditions.
In the early stages, oily stool can often go unrecognized because of its minimal and nonspecific symptoms.
This is why it’s important to reach out to your doctor or provider as soon as you recognize any changes in your stool.
Chronic gallstones are hard particles (usually made up of cholesterol or bilirubin) that develop in the gallbladder.
These particles can block the bile duct, also known as cholestasis, which can disrupt the digestion of food (especially fats) and cause oily stools.
In addition to causing bile duct obstruction and oily stools, gallstones can cause gallbladder pain.
The main symptom of gallbladder pain is severe pain in the upper right abdomen, which can last for several hours.
When gallstones are present in the gallbladder but don’t cause pain or any symptoms, this is called cholelithiasis.
In rare cases, oily stool can be a sign of pancreatic cancer.
Tumors that obstruct the pancreatic duct can lead to exocrine pancreatic insufficiency (EPI), causing oily stools.
Additional symptoms of pancreatic cancer, if present, can also include:
- Yellowing of the skin and eyes
- Pain in the abdomen and back
- Unintentional weight loss
If you’re experiencing the above symptoms in addition to oily stools, it’s important to be seen by your doctor or healthcare provider as soon as possible.
Celiac disease is one of the most common causes of fat malabsorption, which can lead to oily stools.
A chronic digestive and immune disorder that damages the small intestine, celiac disease is triggered by eating foods containing gluten.
Children are more likely to experience digestive symptoms than adults, which include:
- Chronic diarrhea
- Lactose intolerance
- Pain in the abdomen
- Oily, bulky, and foul-smelling stools
Chronic liver disease
Chronic or long-term liver disease, including cirrhosis, primary biliary cholangitis (PBC), and primary sclerosing cholangitis (PBS) can damage the body’s ability to absorb bile acids.
This can cause bile acid deficiency, which can lead to oily stools.
Diet-related causes of oily stool are usually related to a trigger from a known condition.
For example, if you’re lactose intolerant and consume milk products, that can cause oily stools.
Similarly, if you have celiac disease and consume gluten, this can also cause oily stools.
Cystic fibrosis is another common cause of malabsorption that can lead to oily stools.
Affecting roughly 35,000 people in the United States, cystic fibrosis is a genetic disorder that causes problems with breathing and digestion.
The condition is marked by a thick mucus which can block the airways as well as prevent proteins from reaching the intestines, making it difficult for the body to properly absorb nutrients from food.
Symptoms of cystic fibrosis include:
- Salty-tasting skin
- A cough that doesn’t go away (which can also be thick with mucus or blood)
- Wheezing or shortness of breath
- Chronic lung or sinus infections
- Growths in the nose
- Inadequate growth or weight gain in childhood
- Oily, foul-smelling stools
Other conditions affecting the small intestine
Other diseases and infections that affect the small intestine can cause oily stool.
- Whipple disease
- Tropical sprue
- Small intestinal bacterial overgrowth (SIBO)
- HIV enteropathy
The primary symptom of steatorrhea is oily or greasy stools.
Additional symptoms and signs of steatorrhea include:
- Bulky, pale, and foul-smelling stools
- Floating stools
People who have steatorrhea caused by fat malabsorption may also experience:
- Chronic diarrhea
- Abdominal discomfort
- Weight loss
In severe cases, loss of subcutaneous fat and muscle wasting may also occur.
Diagnosing the cause of steatorrhea typically involves an evaluation, which includes a history and physical exam with your doctor or healthcare provider.
After the evaluation, you may need further testing which could include laboratory tests, radiological images, endoscopy, colonoscopy, or more invasive testing.
Xylose is a type of sugar that is easily absorbed by the intestines in healthy individuals.
Your doctor or healthcare provider may order a D-xylose test, also called a xylose test, xylose tolerance test, or xylose absorption test, if they suspect malabsorption is the cause of your oily stools.
The test involves collecting a sample of your urine and blood.
Before and after your sample is collected, you will be asked to drink a solution of eight ounces of water mixed with a small amount of the sugar xylose.
For the urine portion of the test, you will be asked to collect all of the urine you produce for five hours after drinking the solution.
Your doctor or healthcare provider may order a qualitative fecal fat test to check for cystic fibrosis, celiac disease, or diseases of the pancreas.
A qualitative fecal fat test measures the amount of fat globules in your stool.
Normal ranges are:
- Fewer than 60 neutral fat globules
- Fewer than 100 fatty acid globules
A quantitative fecal fat test will measure the total amount of fat in your stool.
Unlike a qualitative fecal fat test, you may be required to collect your stool over a series of days with a quantitative fecal fat test.
Normal ranges for a quantitative test are:
- 2-7g/24h, with fat being less than 20% of the solid stool sample (keep in mind that a solid, formed stool is necessary for testing)
Depending on the suspected cause of your oily stools, your doctor or healthcare provider may order other tests. These may include a serum tissue transglutaminase IgA antibodies test for the evaluation of celiac disease.
Treatment will vary based on your unique situation.
Depending on the cause of your oily stools, dietary changes, vitamin supplementation, and other treatments may be recommended.
When To See a Medical Provider
It’s a good idea to reach out to your doctor or healthcare provider if you’re noticing oily stools, especially over several days.
Additional symptoms you may want to look out for include:
- Foul-smelling or floating stools
- Abdominal pain or cramping
- Chronic diarrhea
- Nausea or vomiting
- Shortness of breath
- Unintentional weight loss
- Yellowing of the skin or eyes
How K Health Can Help
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K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.
K Health has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references.
Cystic Fibrosis. (2020).
Pancreatic Cancer. (2019).
Xylose Testing. (2021).