Pale Stools (Clay-Colored or White Poop)

Why stool is brown, and why it turns pale

The liver makes bile, a green-yellow fluid that helps digest fat. Bile flows through the bile ducts and gallbladder into the small intestine. Bacteria in the gut convert the bile pigment bilirubin into stercobilin, which colors stool brown.

If bile cannot reach the intestine, stool loses its color and becomes pale, gray or white (doctors call this acholic stool). The bilirubin backs up into the blood instead, which can turn the skin and eyes yellow (jaundice) and the urine dark, as the kidneys excrete it.

Causes of pale stools

Bile duct blockage

Biliary obstruction is the most important cause to identify:

• Gallstones in the common bile duct: often with upper right abdominal pain, sometimes coming and going. See gallstones.
• Cholangitis: infection behind a blockage, causing fever, chills, jaundice and pain. This is an emergency.
• Pancreatic cancer: a tumor in the head of the pancreas can press on the bile duct, causing painless jaundice, itching, weight loss and pale stools. See pancreatic cancer.
• Bile duct narrowing (strictures) after surgery, from primary sclerosing cholangitis, or from bile duct cancer.

Liver disease

• Hepatitis: viral (hepatitis A, B, C), alcohol-related or drug-induced inflammation of the liver can reduce bile flow.
• Primary biliary cholangitis: an autoimmune disease of the small bile ducts, mostly in middle-aged women, with itching and fatigue.
• Cirrhosis and liver cancer.
• Medicines: some antibiotics (such as amoxicillin-clavulanate), anabolic steroids and other drugs can cause cholestasis.

Malabsorption

When fat is not absorbed, stools become pale, bulky, greasy and foul-smelling (steatorrhea). Causes include chronic pancreatitis, pancreatic insufficiency, cystic fibrosis, celiac disease and giardia infection.

Harmless causes

• Barium from a barium swallow or enema turns stool white or pale for 1 to 3 days.
• Large doses of antacids containing aluminum hydroxide, and bismuth subsalicylate (which can also turn stools black).
• Diet: a very high-fat meal or diets low in pigment can make stool lighter, but not truly clay-colored.

Pale stools in babies

Breastfed babies normally have mustard-yellow stools, and formula-fed babies yellow-brown to green. Pale yellow, gray, chalky-white or clay-colored stools in a baby are not normal.

The most important cause is biliary atresia, a rare condition in which the bile ducts are blocked or absent. Signs usually appear between 2 and 8 weeks of age: jaundice lasting beyond 2 weeks, pale stools and dark urine (normally a newborn's urine is almost colorless). Surgery (the Kasai procedure) works best if done before about 60 days of age, so early recognition matters. Many countries use a stool color card to help parents spot pale stools.

If your baby has pale stools, contact your pediatrician the same day and, if you can, take a photo or bring a diaper.

How doctors find the cause

1. History and examination: pain, fever, weight loss, alcohol, medicines, itching, recent travel and checking for jaundice and an enlarged liver.
2. Blood tests: bilirubin (total and conjugated), liver enzymes (ALP, GGT, ALT, AST), clotting tests, blood count, and hepatitis tests.
3. Abdominal ultrasound: the first imaging test; shows gallstones, dilated bile ducts and liver changes.
4. MRCP: an MRI scan of the bile ducts and pancreas.
5. ERCP: an endoscope passed through the mouth into the duodenum to view, unblock, remove stones from or stent the bile duct.
6. CT scan or endoscopic ultrasound: for suspected pancreatic or bile duct tumors.
7. Stool tests: fecal elastase for pancreatic insufficiency, fat or giardia tests.

Treatment

Treatment depends on the cause:

• Gallstones in the bile duct: removal by ERCP, then usually gallbladder removal.
• Cholangitis: antibiotics and urgent drainage of the bile duct.
• Tumors: stenting to relieve jaundice, plus surgery, chemotherapy or other cancer treatment.
• Hepatitis: antiviral treatment, stopping alcohol or the causative medicine.
• Primary biliary cholangitis: ursodeoxycholic acid and other medicines.
• Malabsorption: pancreatic enzyme supplements, a gluten-free diet for celiac disease, or antiparasitic treatment.
• Biliary atresia: Kasai surgery, and later liver transplant if needed.

Once bile flow returns, stool color usually returns to brown within days.

Frequently asked questions

What do pale stools mean?

Persistently pale or clay-colored stools usually mean bile is not reaching the intestine, often due to a blocked bile duct, gallstones, hepatitis or another liver problem. They can also come from fat malabsorption. A single pale stool after barium or antacids is harmless.

Are pale stools and dark urine serious?

Yes, this combination suggests bile is backing up into the blood, which happens with bile duct blockages and liver disease. It often comes with yellowing of the skin or eyes. See a doctor promptly, and urgently if you also have fever or abdominal pain.

Can stress cause pale stools?

Stress can change bowel habits and speed up transit, which may make stool lighter in color, but it does not cause truly clay-colored or white stools. Persistently pale stools should be checked with liver blood tests rather than blamed on stress.

What foods cause pale stools?

Food rarely causes genuinely pale stools. A very fatty meal or a diet low in pigment can lighten stool slightly. Barium tests and large doses of antacids or bismuth medicines are the common non-disease causes. Clay-colored stools that persist need medical assessment.

Should I worry about pale stools in my baby?

Yes. Pale, gray, white or clay-colored stools in a baby are not normal and can be an early sign of biliary atresia or another liver problem, which need treatment within weeks. Contact your pediatrician the same day and bring a photo or diaper.