Green Mucus in Stool: Dietary Causes, Medications, Infections, and When to See a Doctor

Common Benign Causes

• Diet – Leafy greens (spinach, kale), green food coloring, iron-rich foods.
• Medications – Iron supplements, antibiotics (especially cephalosporins), antacids with aluminum hydroxide.
• Rapid Transit – Bile (green) doesn't have time to turn brown; seen with diarrhea.

Potentially Concerning Causes

• Bacterial Infection – Salmonella, Shigella, Campylobacter, C. difficile; often with fever, abdominal pain, bloody diarrhea.
• Inflammatory Bowel Disease – Crohn's, ulcerative colitis; mucus + blood + urgency.
• Malabsorption – Celiac, pancreatic insufficiency; steatorrhea, weight loss.

When to Seek Care

Persistent green mucus (>3 days), accompanied by fever, severe pain, blood, weight loss, or dehydration. Stool culture, PCR, calprotectin, or colonoscopy may be indicated.