What causes poop smells like sewer gas?

Why does poop smell like sewer gas? A strong sewer-like odor in stool typically occurs when digestive changes, malabsorption, or gut infections cause bacteria to produce excess sulfur compounds and other pungent chemicals during digestion.

Common causes include:

• Bacterial or parasitic infections (such as Giardia or C. difficile)
• Malabsorption disorders like celiac disease or lactose intolerance
• Inflammatory bowel conditions such as Crohn's disease or ulcerative colitis
• High-sulfur diets rich in eggs, meat, garlic, or cruciferous vegetables
• Medication side effects, particularly antibiotics

While an occasional foul-smelling stool is usually harmless, persistent sewer-like odor—especially when paired with diarrhea, weight loss, or abdominal pain—may signal an underlying condition worth investigating.

Because the causes range from simple dietary triggers to infections that need treatment, guessing can delay relief. A free, instant, AI-powered symptom check can help you pinpoint likely causes based on your specific symptoms and guide you toward the right next steps—whether that's a dietary tweak, a pharmacy visit, or seeing a doctor. It takes just a few minutes and could save you days of worry.

Reviewed for medical accuracy: 07/15/2026