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What causes stinky diarrhea?

Diarrhea refers to loose, watery stools that occur more frequently than usual. It’s very common and usually improves on its own within a few days. However, diarrhea can sometimes have an unusually bad odor, which is often described as “stinky.” This type of diarrhea is often caused by an infection or condition that affects the digestive system.

Some common causes of stinky diarrhea include:

  • Bacterial infections
  • Viral infections
  • Parasitic infections
  • Food intolerances
  • Malabsorption disorders
  • Bowel obstruction

In many cases, stinky diarrhea will go away on its own without treatment. However, it’s important to see a doctor if it persists for more than a few days or is accompanied by severe symptoms like bloody stool, high fever, or dehydration. Identifying and treating the underlying cause can help stop stinky diarrhea and prevent complications.

What diseases cause stinky diarrhea?

Several different diseases and conditions can lead to foul-smelling diarrhea. Some of the most common include:

Bacterial infections

Bacterial infections are a common cause of stinky diarrhea. Some types of bacteria that can cause diarrhea include:

  • Salmonella – Common source is contaminated poultry.
  • Shigella – Passed from person to person, often with poor hygiene.
  • Campylobacter – Found in undercooked poultry, unpasteurized milk.
  • Clostridium difficile – Overgrowth often after antibiotic treatment.
  • Escherichia coli – Certain strains spread through contaminated food/water.

These bacteria spread through the fecal-oral route, meaning ingestion of microscopic amounts of fecal matter from an infected person or animal. Symptoms include foul-smelling, watery diarrhea, abdominal cramping, nausea, and fever. Treatment involves hydration and sometimes antibiotics.

Viral infections

Viruses are another common cause of smelly diarrhea. Examples include:

  • Norovirus – Extremely contagious, often causes outbreaks.
  • Rotavirus – Common cause of diarrhea in infants and children.
  • Adenovirus – Respiratory virus that can also cause gastroenteritis.

These viruses damage the intestinal lining, leading to inflammation and malabsorption. This allows smelly fluid from the intestines to leak out. Symptoms include watery diarrhea, vomiting, abdominal pain, fever, and body aches. Viral infections cannot be treated with antibiotics and just require supportive care.

Parasitic infections

Certain parasites can take up residence in the intestines and cause foul diarrhea:

  • Giardia – Contracted from contaminated food/water sources.
  • Cryptosporidium – Found in contaminated swimming pools/water.
  • Entamoeba histolytica – Causes amoebic dysentery.

These parasites irritate the bowel and can lead to stinky diarrhea containing blood and mucus. Treatment involves prescription anti-parasitic medication.

Food intolerances

Food intolerances occur when the body lacks enzymes to properly digest certain foods. The most common is lactose intolerance – lacking lactase to break down milk sugars. Other problematic foods include:

  • Fructose
  • Sorbitol
  • Gas-producing foods like beans, onions, cabbage

When these foods are eaten, they ferment in the colon leading to smelly gas and diarrhea. Eliminating the problematic foods leads to improvement.

Malabsorption disorders

Malabsorption occurs when the small intestine cannot properly absorb nutrients. This leads to osmotic diarrhea as the unabsorbed compounds pull water into the intestines. Examples include:

  • Celiac disease
  • Inflammatory bowel disease
  • Short bowel syndrome
  • Pancreatic insufficiency

These conditions can cause fatty, foul-smelling stools. Treatment involves dietary changes and medications tailored to the specific disease.

Bowel obstruction

A bowel obstruction blocks the normal flow of intestinal contents. This can lead to a buildup of smelly stool and gas. Causes include:

  • Tumors
  • Scar tissue
  • Hernias
  • Foreign objects
  • Twisted bowel

Symptoms include severe abdominal pain, bloating, nausea and stinky diarrhea. Treatment may involve gently flushing out the colon or surgically removing the obstruction.

When to see a doctor

Stinky diarrhea often resolves on its own without treatment. However, see a doctor if it persists more than 2 days or you have any of the following:

  • High fever over 101°F (38°C)
  • Blood or pus in stool
  • Persistent vomiting
  • Abdominal pain or tenderness
  • Dehydration symptoms like dizziness, dry mouth
  • Recent antibiotic use
  • Weak immune system
  • Travel to developing country recently

These signs could indicate a serious condition requiring medical treatment. Prompt diagnosis and treatment can help ease symptoms and prevent complications.

What diagnostic tests are done?

To determine the cause of stinky diarrhea, the doctor may recommend:

Stool culture

A stool sample is sent to a lab to check for bacterial, viral, or parasitic infections. Identifying the specific organism helps guide treatment.

Stool ova and parasites exam

A microscope is used to visually inspect the stool sample for parasites and eggs. This can detect giardia, cryptosporidium, and other infections.

Blood tests

Blood tests can check for markers of inflammation indicating inflammatory bowel disease. Blood counts may show anemia from GI bleeding or infection.

Endoscopy and biopsy

A tiny camera on a tube (endoscope) is used to visually inspect the GI tract. Small samples can be taken for biopsy to test for celiac disease and other malabsorption disorders.

Imaging tests

CT scan, MRI, or abdominal x-ray may be done to check for bowel obstruction or other abdominal issues. Contrast x-rays can assess for malabsorption problems.

Hydrogen breath test

This checks for lactose intolerance and bacterial overgrowth by measuring breath hydrogen after ingesting a sugar solution. High levels indicate malabsorption.

Identifying the specific cause through testing allows proper treatment to be implemented.

How is the cause of stinky diarrhea treated?

Treatment for smelly diarrhea depends on the underlying cause:

Bacterial infections

Antibiotics are used to kill the bacteria. It’s important to complete the full course as directed, even if you start feeling better. Drink lots of fluids to prevent dehydration.

Viral infections

There are no medications that kill intestinal viruses. Treatment involves getting plenty of rest and staying hydrated. Over-the-counter anti-diarrheal medications can sometimes be used.

Parasitic infections

Anti-parasitic medications are prescribed to kill the organism. The specific medicine depends on the type of parasite. Sanitation measures may be needed to prevent reinfection.

Food intolerances

Avoiding problematic foods is key. Taking lactase enzyme supplements can help digest dairy. Slowly reintroducing foods one at a time can help identify triggers.

Malabsorption disorders

This involves following a gluten-free or low-fat diet, taking vitamin/mineral supplements, and taking medications tailored to the specific disease. Surgery may be an option for some conditions.

Bowel obstruction

Mild cases may resolve with bowel rest and IV fluids. Otherwise, surgery is needed to remove the obstruction. Laxatives should not be used if obstruction is suspected.

Identifying and treating the cause provides symptom relief and prevents recurrent stinky diarrhea episodes. See your doctor promptly if symptoms persist.

Home remedies for stinky diarrhea

Several natural remedies may help reduce symptoms of foul-smelling diarrhea:

  • Probiotics – Live bacteria that help restore normal gut microbiome. Common options are yogurt with live cultures or probiotic supplements.
  • Chamomile tea – Has anti-inflammatory and anti-spasmodic properties that can help soothe the GI tract.
  • Mint tea – The menthol in peppermint tea can ease intestinal cramping and spasms.
  • Rice water – The starch provides calories/electrolytes and coats the irritated intestine.
  • Avoid dairy – Dairy can worsen diarrhea by stimulating the gut. Avoid milk, cheese, ice cream when sick.
  • BRAT diet – Bananas, rice, applesauce, and toast provide gentle nutrition.

Stay well-hydrated, get plenty of rest, and consult your doctor if home treatments don’t improve your stinky diarrhea.

How can stinky diarrhea be prevented?

You can reduce your risk of smelly diarrhea by:

  • Washing hands thoroughly with soap and water before eating and after using the bathroom.
  • Only consuming pasteurized dairy products.
  • Cooking food thoroughly, especially meat.
  • Washing all fruits/vegetables thoroughly.
  • Drinking only purified water when traveling.
  • Avoiding swallowing recreational water (pools, lakes, etc).
  • Getting regularly tested for food intolerances.
  • Getting travel vaccines when going to developing countries.

Practicing good hygiene and food safety habits can help prevent many infections leading to foul-smelling diarrhea. High-risk individuals should take extra precautions.

When to seek medical care

You should seek prompt medical attention if you have:

  • Blood or pus in stool
  • Dehydration symptoms like dizziness, confusion, rapid heart rate
  • Inability to keep down fluids due to vomiting
  • Severe abdominal pain
  • Fever over 102°F (39°C)
  • Symptoms lasting more than 48 hours
  • Recently taken antibiotics
  • A weakened immune system

These red flag symptoms could indicate a serious condition requiring treatment to prevent dangerous complications.


Stinky diarrhea is often caused by infections that damage the intestinal lining. Bacteria, viruses, and parasites can lead to foul-smelling stools by causing inflammation, malabsorption issues, gas, and fluid leakage. Food intolerances, bowel blockages, and certain diseases can also lead to unpleasant odors.

Diagnostic testing like stool cultures and endoscopy can identify the underlying cause. Treatment will depend on the specific diagnosis but may include antibiotics, anti-parasitics, dietary changes, probiotics, and surgery for obstructions. With prompt care, most causes of smelly diarrhea can be successfully managed and prevented from recurring. Practicing good hygiene provides the best protection.