John P. Cunha, DO, is a U.S. board-certified Emergency Medicine Physician. Dr. Cunha's educational background includes a BS in Biology from Rutgers, the State University of New Jersey, and a DO from the Kansas City University of Medicine and Biosciences in Kansas City, MO. He completed residency training in Emergency Medicine at Newark Beth Israel Medical Center in Newark, New Jersey.
Changes in stool color are usually harmless and due to changes in diet. The
normal color of stool is brown, which is due to a substance called bilirubin,
which is a substance found in bile. As it passes through the intestines it
changes from light to a dark brown color.
In some cases, change in stool color can be caused by medical conditions or
medications. If your stool is:
Green: This may occur when you have
diarrhea and stool moves through the intestines too quickly. It can also be
caused by eating green leafy vegetables or foods with green or purple food
Black stool: This is usually
foul-smelling and is caused by upper intestinal bleeding (stomach or upper small
intestine, ulcers, or tumors. It may also be caused when you take iron
supplements or bismuth (Pepto Bismol).
Maroon or purple stool: This is caused
by intestinal bleeding (usually in the small intestine or first part of the
colon), ulcers, tumors, Crohn's disease, ulcerative colitis, or infections.
Bright red stool: This occurs when
bright red blood gets mixed with or covers the stool as it passes through the
rectum. This is caused by hemorrhoids, colon polyps, rectal fissures, massive
gastrointestinal bleeding, or colon cancer.
Clay-colored stool (amelanotic): This
is caused when the bile duct from the liver and gallbladder is blocked. No bilirubin reaches the intestine to help break down your food and the stool does
not change to its usual brown color.
Pale yellow stool: This is usually
greasy and foul smelling, and is caused by problems with the pancreas. These
pancreatic disorders include pancreatitis, pancreatic cancer, and cystic
fibrosis. It can also be caused by celiac disease.