Green stool — when your feces look green — is usually the result of something you ate, such as spinach. Certain medications or iron supplements also can cause green stool.

Newborns pass a dark green stool called meconium, and breast-fed infants often produce yellow-green stools. In older children and adults, green stool is uncommon. It's rarely cause for concern.

Infants

Infants might have green stool as a result of:

• Not finishing breast-feeding entirely on one side, thus missing some of the high-fat-content breast milk, which affects the digestion of the milk
• Protein hydrolysate formula, which is used for babies with milk or soy allergy
• Lack of normal intestinal bacteria in breast-fed infants
• Diarrhea

Children and adults

Causes of green stool include:

• Diet high in green vegetables, such as spinach
• Food dyes
• Diarrhea
• Iron supplements

Call your doctor if you or your child has green stool for more than a few days. Green stool often occurs with diarrhea, so drink plenty of fluids and seek immediate medical attention if you or your child becomes dehydrated.