Patient: What would cause dark green stools in adults for weeks at a time?
Doctor: Dark green colored stools could be caused by a number of reasons. Consumption of large amount of green colored vegetable es rich in chlorophyll, certain food coloring agents and iron supplements, digestive problems and malabsorption and certain medications and antibiotics can result in dark greenish colored stools. Most often this is a self limiting condition that requires no treatment. However you may want to consult a doctor for stool analysis, if you develop abdominal pain, fever or vomiting.