What color is considered normal for stool?

Normal stool color typically ranges from light to dark brown, with variations influenced by diet, bile pigment metabolism, and gastrointestinal transit time. The characteristic brown hue primarily results from the breakdown of bilirubin—a byproduct of hemoglobin degradation—into stercobilin by colonic bacteria. A consistent medium-brown color usually indicates healthy liver function, adequate bile production and secretion, and normal intestinal motility.

Minor, transient color changes are common and often benign—for example, green stools may occur with rapid transit (e.g., during mild gastroenteritis or high intake of leafy greens), while reddish or purple hues can follow consumption of beets, red berries, or food dyes. Black, tarry stools (melena) or bright red blood per rectum (hematochezia), however, warrant prompt medical evaluation, as they may signal upper or lower gastrointestinal bleeding, respectively. Similarly, persistent clay-colored or pale stools suggest impaired bile flow—potentially due to biliary obstruction, hepatitis, or cholestatic liver disease—and should be investigated without delay.

If stool color changes are accompanied by other symptoms such as abdominal pain, unintended weight loss, fatigue, jaundice, or alterations in bowel habits (e.g., chronic diarrhea or constipation), a thorough clinical assessment—including history, physical examination, and targeted laboratory or imaging studies—is essential to identify underlying pathology.