Common Causes of Oily Diarrhea

There are many causes of oily bowel movements in children and adults. Individuals can identify oily bowel movements by noticing oil droplets floating in the toilet water, stools with white or yellow fatty components, stools that float (due to the large oil component) or even orange waxy bowel movements.

As discussed below, oily bowel movements can occur as a side effect of medications, as a result of consuming a particular food, or as a symptom of several different medical conditions.

Oily bowel movements from medications:

Orlistat is a drug commonly used to promote weight loss. Alli is the brandname version of Orlistat and is widely available over-the-counter. Orlistat works by inhibiting an enzyme called lipase that is released from the stomach and pancreas. Lipase works in the gastrointestinal system to break down fat.

By inhibiting lipase, Orlistat causes fat malabsorption. This is the reason that Orlistat is associated with a number of side effects including oily spotting, fecal incontinence, fecal urgency, and increased defecation.

Oily bowel movements from foods:

Oily stools are also caused by the consumption of another substance: fish. There are two fish in particular that can cause oily stools. These bowel movements are often specifically an orange, waxy diarrhea and have the medical name keriorrhea. The two fish that cause oily bowel movements are Escolar and oilfish.

Both Escolar and oilfish are frequently caught as by-catch of tuna and other fishes. These fish have a specific indigestible type of fat known as wax esters. The wax esters build up at the rectum and eventually cause an oily diarrhea.

Oily bowel movements from medical conditions:

Medical conditions that can result in oily bowel movements include cystic fibrosis, celiac sprue, inflammatory bowel disease, acute or chronic pancreatitis and pancreatic cancer.

Cystic fibrosis is a genetically inherited disease that causes defective ciliary clearance (cilia are sweeping hairs that line airways) of mucous from the lungs. However, cystic fibrosis is also commonly associated with pancreatic insufficiency.

Pancreatic insufficiency means that there are decreased amounts of pancreatic enzymes released into the intestines to metabolize food components. Decreased amounts of lipase, in particular, cause oily bowel movements.

Acute pancreatitis, chronic pancreatitis and cancer of the head of the pancreas all cause oily bowel movements because of decreased release of lipase into the intestine. Acute pancreatitis is associated with sudden onset severe abdominal pain. Chronic pancreatitis has persistent abdominal pain and chronic malabsorptive diarrhea. Pancreatic cancer is associated with weight loss, painless jaundice and oily diarrhea (also called steatorrhea).

Celiac sprue and inflammatory bowel diseases, such as ulcerative colitis and Crohn's disease, are illnesses that affect the intestines. Celiac sprue and inflammatory bowel disease (IBD) are occasionally associated with oily bowel movements. The oily bowel movements may result from poor absorption of fats due to inflamed intestinal walls.

There are a variety of causes of oily bowel movements. Some of these causes represent serious medical conditions. Therefore, individuals who are experiencing oily stools should discuss their concerns with their healthcare provider.