Floating Stool: What It Means and When to See a Doctor

Floating stool is usually caused by extra gas trapped in the stool, most often from what you have eaten, and on its own it is rarely a sign of illness. Stools that are greasy, oily, pale or unusually foul-smelling and hard to flush are a different signal, because they can mean fat is not being absorbed, and those are the ones worth getting checked.

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Most people never think about whether their stool sinks or floats until it changes. Then a search turns up everything from harmless gas to pancreatitis and cancer, with little help in telling which is which.

The useful distinction is between stool that simply floats and stool that looks greasy or oily. This guide explains what each one usually means, what changes if you have had your gallbladder removed, and which signs need a doctor.

What Does Floating Stool Mean?

Floating stool usually means your stool contains more gas than usual, and it is most often a result of something you ate. MedlinePlus describes floating stools as usually harmless and not, by themselves, a sign of illness, and notes that a change in diet that increases gas is the most common cause [1].

The idea that floating means "too much fat" is common, but the research points the other way. In a 1972 study in the New England Journal of Medicine, researchers examined stools from 33 healthy people, 9 of whom had floating stools, and found that the floating stools sank once their gas was compressed [2]. Without the gas, floaters and sinkers had much the same density [2].

The study also looked at six people with steatorrhea, the medical term for too much fat in the stool. Their stools held roughly normal amounts of gas and were lighter mainly because of extra water, not fat, and the authors concluded that a floating stool should not be taken as a sign of steatorrhea [2]. Floating alone tells you little; the look, smell and pattern of the stool tell you much more.

What's healthier, sinkers or floaters?

Neither is healthier in itself. More than a quarter of the healthy volunteers in the 1972 study had floating stools [2]. What matters more is whether your stool has changed, for how long, and whether other symptoms came with it.

What Causes Floating Stool?

Most floating stool comes from gas [2]. Bacteria in the large intestine make it as they break down carbohydrates that were not absorbed higher up, and swallowed air from eating quickly, chewing gum or fizzy drinks adds more [3].

1. Fiber-rich and gas-producing foods

Beans, peas and lentils, vegetables such as broccoli and cauliflower, fruits such as apples and pears, and whole grains are among the foods most likely to cause gas [4]. Cabbage, onions and garlic are frequent culprits too [5].

2. Lactose and sugar-free sweeteners

About 36 percent of people in the US have lactose malabsorption, so some milk sugar reaches the colon undigested [6] and is fermented into gas. Sugar alcohols such as sorbitol, found in sugar-free gum and candy, can cause gas and bloating at doses as small as 10 grams in sensitive people [7].

3. A stomach bug or Giardia

A gastrointestinal infection can cause floating stools [1]. Giardia, a parasite that spreads through contaminated water, food or surfaces or from person to person, can cause diarrhea, gas, cramps and smelly, greasy poop that can float, usually for two to six weeks [8, 9].

4. Irritable bowel syndrome

In a French study of 1,252 patients referred with functional gut disorders, floating stools were reported by 26 percent of those with functional bowel disorders and 3 percent of the rest, and mixed-type IBS, where constipation and diarrhea alternate, was the only condition independently linked to them [10]. That is an association in clinic patients, not a cause.

Floating or Greasy: How Can You Tell the Difference?

Fatty stools are typically looser, smellier and paler, sometimes clay-colored; they may float, look greasy or foamy and be hard to flush [11]. An occasional fatty stool after a very fatty meal can be normal, while greasy stools that keep coming back signal a problem [11].

What you notice	What it often means	What to do
Floating stool that otherwise looks normal	Extra gas, usually from food	Look for a food pattern and give it a week or two
Greasy, oily, pale or foul stools that keep returning	Possible fat malabsorption	Book a doctor's visit for tests
Floating with weight loss or pain that will not settle	A digestive condition that needs a diagnosis	Book a doctor's visit soon
Pale or clay-colored stool with dark urine or yellow skin, or black or bloody stool	Possible bile duct blockage or bleeding	Get care the same day

What Causes Greasy or Oily Stool?

Greasy or oily stool usually means some of the fat you ate was not digested or absorbed. Fat digestion needs enzymes from the pancreas, bile from the liver and a healthy small intestine [12], so a problem at any step can leave fat in the stool. It often comes with bloating, gas and chronic diarrhea [13].

1. A very rich meal or certain foods

A single large, fatty meal can occasionally produce a fatty stool in anyone [11]. Some fish cause a more dramatic version: escolar, sometimes called "white tuna," and oilfish contain wax esters the body cannot digest, which can cause oily diarrhea or oily leakage after a meal, especially if a lot is eaten [14, 15, 16].

2. The pancreas

When the pancreas releases too few digestive enzymes, called exocrine pancreatic insufficiency, fat passes through undigested; causes include chronic pancreatitis, cystic fibrosis and pancreatic cancer [11]. Chronic pancreatitis tends to cause upper abdominal pain that may spread to the back or worsen after eating, along with diarrhea, weight loss and greasy, foul-smelling stools, and heavy alcohol use is one of its most common causes [17]. Once it is confirmed, your doctor may prescribe pancreatic enzymes such as Creon [18].

3. Celiac disease and other small-intestine conditions

Celiac disease damages the small intestine and can cause loose, greasy, bulky and bad-smelling stools, along with bloating, gas and diarrhea [19]. Crohn's disease and small intestinal bacterial overgrowth (SIBO) can also interfere with fat absorption [11, 20].

4. Liver and bile duct conditions

Bile acids act as detergents that help digest fat [21], so conditions that reduce bile reaching the intestine can cause fatty stools. Cleveland Clinic lists primary biliary cholangitis, primary sclerosing cholangitis, cholestasis (slowed bile flow), cirrhosis and liver failure among them [11]. Pale stools can also mean too little bile or a blocked bile duct [22].

5. Medicines

Orlistat, sold over the counter as Alli and by prescription as Xenical, works by preventing the absorption of some of the fat you eat [23]. Its label says you may get gas with oily spotting, loose stools and more frequent stools that may be hard to control, and that a low-fat diet lowers the chance [24].

Why Is My Poop Floating After Gallbladder Removal?

After gallbladder removal, floating or loose stools can have the same food and gas causes as in anyone, and far less bile is on hand at once after a fatty meal [25], so large, rich meals may add to them. Most people still absorb fat normally after surgery [26], though one study found daily fecal fat slightly but significantly higher than before [27]. Spreading fat across the day tends to help, as our guide to eating fatty foods without a gallbladder explains.

Loose stools are common in the first months: in one German study, 47 percent of people had them at one month after surgery and 33 percent at three months [28]. When diarrhea is watery, urgent and lasting, bile acid diarrhea becomes more likely, and gallbladder removal is one of its recognized causes [29]. Our articles on diarrhea after gallbladder removal and bile acid diarrhea after gallbladder removal cover both.

Greasy stools that keep returning after surgery need the same tests as in anyone, because the pancreas, celiac disease and bacterial overgrowth can all be involved [20]. Pale stools are different again. Bile duct stones can be found days to years after gallbladder removal [30], and a stone that blocks the duct can cause pain, fever, jaundice and clay-colored stools [31]. Our guide to gallstones without a gallbladder explains more.

Is Floating Stool a Sign of Cancer?

Floating stool on its own is not considered a sign of cancer: most of it is caused by gas [2], and floating stools are not, by themselves, a sign of illness [1]. The worry comes from pancreatic cancer, which can cause greasy stools as part of a wider picture [32].

According to the American Cancer Society, early pancreatic cancer often causes no symptoms. When it does, jaundice is one of the first signs for most people, and it can come with dark urine and light-colored or greasy stools that may float; unintended weight loss, poor appetite and belly or back pain are also common [32]. Even so, gallstones, hepatitis and other liver and bile duct diseases cause jaundice much more often [32].

Floating stool is also absent from the society's list of colorectal cancer symptoms, which centers on lasting changes in bowel habits, blood in the stool, belly pain and weight loss [33]. From 45, the more useful step is the colorectal cancer screening the US Preventive Services Task Force recommends [34].

How Do Doctors Find the Cause of Greasy Stool?

Doctors usually start by asking when the change began, how often it happens, what you eat and how the stool looks and smells [1]. Common tests include:

• A fecal fat test, which measures fat in stool collected over up to 72 hours; more than 7 grams a day is abnormal [20, 11]
• Fecal elastase, a stool test that reflects how much enzyme the pancreas is releasing [20]
• Blood tests for celiac disease, which work best if you keep eating gluten until testing is finished [35]
• Stool tests for infections such as Giardia [36], and liver blood tests when bile flow is in question [37]
• Imaging of the pancreas, liver and bile ducts, such as ultrasound, CT or MRI [38, 13, 39]

Treatment depends on the cause [1], and because long-term fat malabsorption can lower vitamins A, D, E and K [40, 11], vitamin levels may be checked too.

What Helps Floating or Greasy Stool at Home?

For floating stool alone, finding and cutting back the food behind it is usually all that is needed [1]. Try one change at a time.

1. Keep a short food diary

Note what you eat and when your stool changes for one to two weeks. Many people spot a link, such as dairy or beans. Sorbitol and other "-ol" sweeteners are an easy cause to test [4].

2. Raise fiber gradually

Fiber is worth keeping, but a sudden jump brings more gas. Soluble fiber such as psyllium tends to cause less gas than insoluble fiber such as bran [5].

3. Do not cut out fat completely

Spreading fat across meals can make sense, but less fat in the stool does not mean the cause has gone. Cleveland Clinic notes that people with malabsorption may need more fat, especially unsaturated fats such as olive oil, avocado, nut butters and oily fish [11], and vitamins A, D, E and K need fat and bile to be absorbed [41].

When Should You See a Doctor About Floating Stool?

Floating stool that comes and goes with your diet is usually harmless, but MedlinePlus advises reporting any changes in your stools or bowel movements [1].

See your doctor soon if you have

• greasy, oily, pale or foul-smelling stools that keep coming back, rather than after one rich meal [11]
• weight loss you cannot explain, especially with greasy stools [1, 13]
• ongoing bloating, cramps or upper abdominal pain, particularly after eating [13, 17]
• a change in bowel habits that lasts more than a few days [33]

Get care the same day if you have

• pale, gray or clay-colored stool with dark urine, or yellowing of the skin or eyes [42, 43]
• diarrhea that lasts more than two days, or six or more loose stools a day [44]
• black, tarry or bloody stools [44], especially with weight loss, dizziness and fever [1]
• severe upper abdominal pain that spreads to your back, with nausea, vomiting or fever [17]
• signs of dehydration, such as extreme thirst, dark urine, dizziness or passing very little urine [44]

After surgery, our guides to digestive problems after gallbladder removal and gas after gallbladder removal cover the related symptoms.

In Summary: Floating Stool and What It Means

Floating stool is usually extra gas from food, lactose, sugar alcohols or swallowed air, and on its own it is not a sign of illness. Greasy, oily, pale or foul-smelling stools that keep returning are the more useful signal of fat not being absorbed, and tests can sort out the cause. Pale stool with dark urine or yellow skin needs same-day care.

From 45, the bowel check that matters most is routine colorectal cancer screening, which is recommended for adults aged 45 to 75 who have no symptoms [34].

Some people's main digestive complaint is a heavy, slow feeling after richer meals. Dr.Primal's TUDCA, a hydrophilic, or water-loving, bile acid that occurs naturally in small amounts in human bile [45], is used to support healthy bile flow. If you would like a starting point, our digestion quiz is a quick way to put your digestion symptoms and habits in order.

This article is for general education and is not a substitute for advice from your doctor. TUDCA is sold as a dietary supplement. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.