Stools - Unusual Color

Definition

• Stool color that is strange or different than normal
• Normal stool colors are any shade of brown, tan, yellow or green
• The only colors that may be caused by a disease are red, black and white
• Dark green may look like black, but dark green is a normal color

Causes of Unusual Stool Color

• Almost always due to food coloring or food additives. 
• Stool color relates more to what is eaten than to any disease.
• In children with diarrhea, the gastrointestinal (GI) passage time is very rapid. Stools often come out the same color as the fluid that went in. Examples are Kool-Aid or Jell-O.  
• The only colors we worry about are red, black (not dark green) and white.

Clues to Unusual Stool Colors

Red:

• "Bloody stools": 90% of red stools are not caused by blood
• Blood from lower GI tract bleeding
• Medicines. Red medicines (like Amoxicillin). Sometimes, other medicines that turn red in the GI tract (such as Omnicef)
• Foods. See list below.

Foods That Can Cause Red Stools:

• Red Jell-O, red or grape Kool-Aid
• Red candy, red licorice
• Red cereals
• Red frosting
• Red food coloring
• Beets
• Cranberries
• Fire Cheetos
• Paprika
• Red peppers
• Rhubarb
• Tomato juice or soup, tomato skin

Black:

• Blood from stomach bleeding (stomach acid turns blood to a dark, tar-like color)
• Foods. Licorice, Oreo cookies, grape juice
• Medicines. Iron, bismuth (Pepto-Bismol)
• Other. Cigarette ashes, charcoal
• Bile. Dark green stools from bile may look black under poor lighting. Smear a piece of stool on white paper. Look at it under a bright light. This often confirms that the color is really dark green.

Green:

• Green stools are always normal, but they can be mistaken for black stools.
• Bile. Most dark green stools are caused by bile.
• Green stools are more common in formula fed than breastfed infants. It can be normal with both.
• Green stools are more common with diarrhea. This is due to a fast transit time through the gut. However, formed stools can also be green.
• Dark green stools may look black under poor lighting. Eating spinach can cause dark green stools.
• Medicines. Iron (such as in formula)
• Foods. See list below.

Foods That Can Cause Green Stools:

• Green Jell-O
• Grape-flavored Pedialyte (turns bright green)
• Green fruit snacks
• Spinach or other leafy vegetables

White or Light Gray:

• Foods. Milk-only diet
• Medicines. Aluminum hydroxide (antacids), barium sulfate from barium enema
• Liver disease. Babies with blocked bile ducts have stools that are light gray or pale yellow.