Why Does My Poop Smell Like Sewage?

The sewage-like odor in stool usually results from bacterial imbalances, diet, or digestive issues affecting gut health.

Understanding the Sewage Smell in Stool

Noticing a sewage smell coming from your poop can be unsettling. While stool naturally has an odor due to the bacteria and waste products it contains, a strong sewage-like smell stands out as unusual. This distinctive foul odor often hints at underlying changes in your digestive system or diet that affect how your gut processes food.

The human digestive tract is home to trillions of bacteria that break down food and produce gases and compounds contributing to stool’s smell. When this balance shifts, or when certain foods are consumed, the odor can change dramatically. The sewage smell is typically caused by sulfur-containing compounds and other waste byproducts that are produced or released in greater quantities than normal.

Key Causes Behind Sewage-Smelling Poop

Several factors can lead to poop that smells like sewage. These include:

1. Bacterial Imbalance (Dysbiosis)

Your gut hosts a complex community of bacteria essential for digestion and immune function. If this balance is disrupted—due to antibiotics, illness, or diet changes—harmful bacteria may flourish. These bacteria can produce sulfur-containing gases like hydrogen sulfide, which smells like rotten eggs or sewage.

2. Diet High in Sulfur-Containing Foods

Certain foods are naturally rich in sulfur compounds. Eating large amounts of these can increase the production of foul-smelling gases during digestion:

Broccoli
Cauliflower
Cabbage
Eggs
Garlic and onions
Red meat

When these foods break down in the large intestine, they can release hydrogen sulfide and other sulfurous gases that contribute to a sewage-like odor.

3. Malabsorption Issues

If your intestines aren’t absorbing nutrients properly—due to conditions like celiac disease, lactose intolerance, or pancreatic insufficiency—undigested food ferments in the colon. This fermentation creates gas and smelly compounds that can make stool smell foul.

4. Infections and Inflammation

Bacterial infections such as Clostridium difficile, parasitic infections, or inflammatory bowel diseases (IBD) like Crohn’s disease and ulcerative colitis can alter stool consistency and smell. These conditions often cause diarrhea with a strong offensive odor resembling sewage due to the presence of pathogenic bacteria and mucus.

The Role of Gut Bacteria in Stool Odor

The gut microbiome plays a starring role in how your poop smells. Beneficial bacteria help digest complex carbohydrates into short-chain fatty acids, which have mild odors. However, when harmful bacteria dominate or when fermentation produces sulfur compounds, odors become more pungent.

Hydrogen sulfide (H₂S), a gas produced by certain gut bacteria when they break down sulfur-containing amino acids, is primarily responsible for the rotten egg or sewage-like smell in stool.

An imbalance favoring sulfate-reducing bacteria increases H₂S production significantly. This happens if you have:

Lack of dietary fiber feeding good bacteria
A diet rich in protein and sulfur compounds
A disrupted microbiome from antibiotics or illness

Nutritional Influences on Stool Smell

Your diet impacts not just what you excrete but also how it smells. Below is a table showing common foods linked with stronger fecal odors due to their composition:

Food Group	Sulfur Content Level	Effect on Stool Odor
Cruciferous Vegetables (Broccoli, Cabbage)	High	Increases hydrogen sulfide production; strong rotten egg smell
Protein-rich Foods (Meat, Eggs)	Moderate to High	Sulfur amino acids metabolized into foul-smelling gases; pungent odor
Dairy Products (Milk, Cheese)	Low to Moderate*	If lactose intolerant: fermentation causes sour, unpleasant smell*

*Only if malabsorbed due to intolerance.

The Impact of Medical Conditions on Stool Odor

Celiac Disease & Gluten Sensitivity

Celiac disease damages the small intestine lining when gluten is consumed, impairing nutrient absorption. This leads to undigested food reaching the colon where bacterial fermentation produces foul-smelling gases similar to sewage.

Lactose Intolerance

Lactose intolerance means your body lacks enough lactase enzyme to digest lactose found in milk products. Undigested lactose ferments in the colon causing gas buildup and strong odors.

Poor Pancreatic Function (Pancreatic Insufficiency)

The pancreas releases enzymes needed for fat digestion. If enzyme production drops (due to chronic pancreatitis or cystic fibrosis), fats remain undigested leading to greasy stools with bad odors caused by bacterial breakdown.

Bacterial Overgrowth & Infection

An overgrowth of harmful bacteria such as Clostridium difficile creates toxins causing diarrhea with an intense foul odor resembling sewage due to excessive bacterial waste products.

Key Takeaways: Why Does My Poop Smell Like Sewage?

➤ Diet impacts odor: Certain foods cause stronger smells.

➤ Gut bacteria play a role: Imbalance can alter scent.

➤ Infections may cause odors: Seek medical advice if persistent.

➤ Medications affect smell: Some drugs change stool odor.

➤ Hydration matters: Dehydration can intensify smells.

Frequently Asked Questions

Why Does My Poop Smell Like Sewage After Eating Certain Foods?

Eating foods high in sulfur, such as broccoli, garlic, and red meat, can increase sulfur-containing gases in your gut. These gases, like hydrogen sulfide, produce a strong sewage-like odor in your stool as they are released during digestion.

Can Bacterial Imbalance Cause My Poop to Smell Like Sewage?

Yes, an imbalance in gut bacteria, often caused by antibiotics or illness, can lead to harmful bacteria producing foul-smelling sulfur gases. This disruption makes your stool emit a strong sewage-like odor that is different from normal bowel smells.

Does Malabsorption Affect Why My Poop Smells Like Sewage?

Malabsorption conditions like celiac disease or lactose intolerance cause undigested food to ferment in the colon. This fermentation produces smelly compounds and gases that can make your poop smell strongly like sewage.

Could Infections Make My Poop Smell Like Sewage?

Bacterial infections such as Clostridium difficile or inflammatory bowel diseases often cause diarrhea with a foul smell. The presence of pathogenic bacteria and mucus can result in a sewage-like odor in your stool.

How Does Gut Health Influence Why My Poop Smells Like Sewage?

Your gut microbiome plays a key role in stool odor. When the balance of bacteria shifts due to diet or illness, it changes how food is broken down and gases are produced, leading to unusual sewage-like smells in your poop.

Troubleshooting Sewage-Like Stool Smell at Home

Monitor Diet: Reduce intake of high-sulfur foods temporarily and observe any changes in stool odor.
Add Fiber: Soluble fiber feeds good gut bacteria which may help rebalance the microbiome and reduce foul odors.
Avoid Dairy if Suspected Intolerance: Cut out milk products for a week; note if stool smell improves.
Stay Hydrated: Proper hydration supports digestion and regular bowel movements which can lessen odor intensity.
Avoid Unnecessary Antibiotics: Antibiotics disrupt gut flora leading to imbalances causing bad-smelling stools.
Mental Health Check:
Mild Probiotics Use:
Mild Exercise:
Keeps Track:

If Persistent Symptoms Arise:

Treatment Options for Persistent Sewage-Smelling Stool Odor

If lifestyle adjustments don’t improve symptoms within a few weeks or if you experience other concerning signs such as severe abdominal pain or unexplained weight loss, professional evaluation is necessary. Your doctor might recommend:
- Labs & Stool Tests:Bacterial Overgrowth Testing:Celiac Disease Screening:Lactose Tolerance Test:PANCREATIC FUNCTION TESTS: E.g., fecal elastase test assessing enzyme output.
- Treatment Plans: This may include antibiotics for infections,
  enzyme supplements for pancreatic insufficiency,
  gluten-free diets for celiac disease,
  and probiotics for microbiome restoration.

Why Does My Poop Smell Like Sewage? | Clear Health Answers