Green stool appears alarming but usually stems from benign causes that gastroenterologists routinely address. Understanding what triggers this color change helps you decide whether medical attention is necessary.
Diet represents the most common culprit. Leafy greens like spinach and kale contain chlorophyll, the pigment that makes plants green. When you consume large amounts, your stool retains this color as it passes through your digestive system. Blueberries, green food coloring, and spirulina supplements produce similar effects. The food moves through your intestines quickly before bile, which turns stool brown, fully processes it.
Bile itself plays the central role in stool color. This digestive fluid produced by your liver starts green but oxidizes to brown as it moves through your colon. When transit time accelerates, you may see green stools. Diarrhea and inflammatory bowel conditions like Crohn's disease speed intestinal movement considerably.
Medications alter stool color too. Antibiotics, particularly those treating bacterial infections, kill beneficial gut bacteria that help break down bile. Chlorophyll supplements and iron supplements both produce green discoloration. Antimalarial drugs and some antihistamines list this side effect as well.
Infections from bacteria or viruses trigger diarrhea with green coloring. Salmonella and E. coli contamination cause rapid intestinal transit, leaving stool green. Most viral gastroenteritis cases resolve independently within days.
Conditions affecting bile production warrant medical evaluation. Liver disease, bile duct obstruction, or gallbladder problems impair bile processing. These require professional assessment.
When to contact your doctor: seek care if green stools persist longer than two weeks, accompany severe abdominal pain, include blood, or occur with unexplained weight loss and fever. If you've started