Steatorrhoea (Fatty Stools): Causes, Symptoms & UK Online Doctor Guide

Steatorrhoea is a digestive symptom characterized by an abnormally high concentration of fat in the faeces. In a healthy digestive system, the body breaks down dietary fats using enzymes (lipase) and bile. If this process is disrupted, undigested fat passes through the intestines, resulting in stools that are notably different in consistency, colour, and smell.

According to NHS guidance, healthy stools can vary, but persistent changes towards a greasy or oily appearance usually indicate an underlying issue with malabsorption. Steatorrhoea is not a disease itself but a clinical sign that your body is failing to absorb vital nutrients effectively.

Patients in the UK often describe steatorrhoea by using specific visual and physical descriptors. Recognising these can help your online doctor narrow down the potential causes. Common features include:

• Oily or Greasy Appearance: Stools may look shiny or have visible oily droplets on the surface of the toilet water.
• Difficult to Flush: Because fat is less dense than water, these stools often float and are notoriously difficult to flush away.
• Pale Colour: Stools are frequently light-coloured, tan, grey, or yellowish rather than the typical brown.
• Foul Odour: The presence of undigested fat and the resulting fermentation by gut bacteria often leads to a particularly pungent, rotting smell.
• Increased Volume: Steatorrhoea often results in bulkier, more frequent movements that may be loose or soft.

Several conditions can lead to fat malabsorption. The NICE (National Institute for Health and Care Excellence) guidelines provide pathways for diagnosing these conditions based on clinical presentation.

Biliary and Liver Issues

Bile is essential for emulsifying fats. If bile flow is restricted—due to gallstones, primary biliary cholangitis, or liver disease—fats cannot be broken down, leading to oily stools.

Exocrine Pancreatic Insufficiency (EPI)

The pancreas produces lipase, the primary enzyme for fat digestion. If the pancreas is damaged (e.g., due to chronic pancreatitis or cystic fibrosis), it cannot secrete enough enzymes, which is a leading cause of severe steatorrhoea.

Small Intestinal Conditions

Conditions that damage the lining of the small intestine, such as coeliac disease or Crohn’s disease, reduce the surface area available for nutrient absorption. If the villi (small finger-like projections) are flattened, fat passes straight through the digestive tract.

Giardiasis and Infections

As noted in UK travel health guidance, certain parasites like Giardia can coat the intestinal wall, physically blocking the absorption of fats and causing sudden-onset foul-smelling diarrhoea.

If you suspect you have steatorrhoea, a GP will typically begin with a detailed history of your symptoms and diet. In the UK, the most common diagnostic tool is the Faecal Elastase test. This is a non-invasive stool sample test that measures the levels of an enzyme called elastase, which is produced by the pancreas. Low levels indicate that the pancreas is not functioning at full capacity.

Other tests may include blood tests to check for vitamin deficiencies (particularly fat-soluble vitamins A, D, E, and K), markers for coeliac disease, or liver function tests. In some cases, imaging such as an ultrasound or CT scan of the abdomen may be required to view the gallbladder or pancreas.

While a single oily stool after a very fatty meal may not be cause for alarm, persistent changes require medical attention. Speaking to an online doctor in the UK is a convenient way to start the investigative process without waiting weeks for an in-person appointment.

You should book a consultation if you experience:

• Greasy, floating stools that persist for more than two weeks.
• Unintentional weight loss despite eating normally.
• Chronic abdominal bloating or cramping.
• Signs of vitamin deficiency, such as night blindness or bone pain.

An online GP can review your symptoms, advise on necessary stool tests, and provide the referrals needed for specialist care or blood tests at a local clinic. This early intervention is vital to prevent long-term malnutrition.

Treatment for steatorrhoea depends entirely on the root cause. If the issue is pancreatic, Pancreatic Enzyme Replacement Therapy (PERT)—such as Creon—is highly effective. These are capsules taken with every meal to replace the enzymes your body isn't making.

For those with coeliac disease, a strict lifelong gluten-free diet is the only treatment, allowing the gut to heal and regain its absorptive powers. If bile duct issues are identified, surgical interventions or medications to improve bile flow may be necessary. Your online doctor can provide initial guidance and help you navigate the NHS pathway or private specialist referrals.