Stool should appear light brown and have little odour, and its appearance is an indicator of digestive health. Diseases, chronic conditions and some medicines, however, can cause stool to become light or pale in appearance.
The digestive fluid bile, produced by the liver, gives stool its usual brown colour. White or pale stool lacks bile and indicates that something is either halting its production or blocking it from reaching the stool.
Several diseases and conditions, some serious, can cause white or pale stool, according to the Mayo Clinic. These include hepatitis, cirrhosis, gallstones, congenital digestive problems or tumours.
Anti-diarrhoea medications, such as Pepto-Bismol, might cause white stool, as can some antacids, antibiotics and anti-fungal medication. A barium enema also usually produces white stool.
Pale stool might have a strong, foul smell or appear greasy, indicating undigested fat. Mucus from the intestines also might lighten the colour of stool, although it usually will come off in water.
Because pale or white stool can indicate serious medical problems, do not try to self-diagnose its cause. If there is no medicinal reason for white stool or it persists for multiple bowel movements, seek medical care immediately.