Normal Stool Color: What You Need to Know
Normal stool color ranges from light to dark brown, though variations including yellow and green can be normal depending on diet, transit time, and age.
Normal Stool Color Range
Normal stool color is primarily determined by the presence of bile pigments and can vary within a healthy range:
- Brown (light to dark): The most common normal stool color in adults, resulting from bilirubin breakdown in the intestines
- Yellow to light brown: Common in breastfed infants and some adults
- Green: Can be normal, especially in infants (nearly half of healthy infants have predominantly green stools for at least one week during their first 17 weeks of life) 1
Factors Affecting Normal Stool Color
Several factors can influence stool color while still remaining within the normal range:
- Diet: Foods with strong pigments (beets, leafy greens, food colorings)
- Medications: Some antibiotics, antacids, and supplements
- Transit time: Faster intestinal transit may result in greener stools
- Age: Infants typically have different stool colors than adults
- Feeding type: Breastfed infants tend to have more yellow stools compared to formula-fed infants 1
When to Be Concerned About Stool Color
While color variations are common, certain stool colors warrant medical attention:
- Pale, clay-colored, or white stools: May indicate biliary obstruction or liver disease 2, 3
- Black or tarry stools: May indicate upper GI bleeding (unless taking iron supplements or certain medications)
- Red or bloody stools: May indicate lower GI bleeding, though occasional blood in infant stool is reported in up to 9.3% of healthy infants 1
Special Considerations for Infants
Stool color patterns in infants differ from adults:
- First week of life: Nearly black stools (meconium) are normal in 3.4% of newborns 1
- Breastfed infants: Typically have more frequent, yellow stools compared to formula-fed infants 1
- Green stools: Common in healthy infants (47.4% have predominantly green stools for at least one week) 1
Recognition Challenges
Healthcare professionals and parents often struggle to correctly identify abnormal stool colors:
- Only two-thirds of parents and healthcare providers correctly recognize all abnormal stool colors 4
- One-third of stools are not correctly identified even by physicians and nurses 3
- Using stool color cards can improve recognition of abnormal stools from 66% to 87% 4
Bottom Line
While brown is the most common normal stool color, variations including yellow and green can be entirely normal. The key concern is persistent pale or clay-colored stools, which may indicate biliary obstruction requiring prompt medical evaluation. Black or bloody stools also warrant medical attention to rule out gastrointestinal bleeding.