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Foul Smelling Stool Symptoms, Causes & Common Questions

The most common cause of foul smelling stool and gas is nutrient malabsorption, meaning the food you eat are not being absorbed properly in the intestines. Causes of this condition include gluten intolerance, IBD, Crohn's disease, or lactose intolerance. Other causes of smelly poop include infection, food poisoning, dehydration, or a side-effect from medication. Read below for more causes and treatment options.

Foul smelling stool symptoms

Everybody poops. And no one's poop smells what you'd call "good." If the smell of your poop is different and clearly offensive, however, there may be a deeper issue at work. In most instances, especially foul-smelling stools are caused by the specific foods one has been eating, an imbalance of gut bacteria, the stomach flu, a gut disease like inflammatory bowel disease (IBS) or Crohn's, malabsorption of nutrients in the intestines or an intestinal infection. However, in some cases, foul-smelling stool can be a sign of a serious health problem as well.

Common accompanying symptoms of foul-smelling stool

Symptoms that may accompany foul smelling stool often include:

Sometimes, however, foul-smelling stools can indicate a more serious internal issue, like colon cancer or a serious problem with the liver.

Serious symptoms of foul-smelling stool

Signs that you need to see a doctor immediately include:

Dietary changes

Changes in diet can often affect the odor of one's stool. Overindulging in Mexican street food, for example, can overwhelm the gut bacteria and lead to foul-smelling stool.

Other causes of foul-smelling stool

Other causes of foul-smelling stool include:

  • Nutrient malabsorption: Your gut absorbs nutrients from the food you eat in the small intestines. The most common cause of foul-smelling stool is when nutrients aren't being absorbed from the gut as they should be. Causes of malabsorption include gluten intolerance, food allergies, lactose intolerance, IBD, Crohn's disease, or ulcerative colitis.
  • Infections: Eating food contaminated with trace amounts of E. coli, viruses, or parasites can cause the intestines to become inflamed and infected resulting in very foul-smelling stools.
  • Medications and herbal supplements: Often, medications and herbal supplements can cause foul-smelling stool or diarrhea that smells very bad. Even taking antibiotics can lead to foul-smelling stool as it disrupts the gut bacteria for some time.

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10 foul smelling stool conditions

The list below shows results from the use of our quiz by Buoy users who experienced foul smelling stool. This list does not constitute medical advice and may not accurately represent what you have.

Irritable bowel syndrome (IBS)

Irritable bowel syndrome (IBS) is a chronic disorder of the large intestine. It is characterized by recurrent abdominal pain and bowel movement issues that can be difficult to treat. Signs and symptoms of IBS are usually not severe or life-threateni...

Chronic gallstones

Gallstones are hardened deposits of digestive fluid that can form in your gallbladder. Your gallbladder is a small, pear-shaped organ on the right side of your abdomen, just beneath your liver.

Rarity: Uncommon

Top Symptoms: nausea, loss of appetite, unintentional weight loss, vomiting, pain in the upper right abdomen

Urgency: Primary care doctor


Gallstones are small, round deposits found in the gallbladder, the organ where bile is stored. Gallstones can be subclassified a number of ways. Oftentimes, gallstones will be referred to as either cholesterol stones or pigment stones depending on the makeup of the gallstone.

Gallstones can also be class...

Chronic hepatitis c

Chronic hepatitis C is a liver inflammation caused by Hepacivirus C.

If someone is infected with hepatitis C and gets the acute form of the disease, there is about a 50% chance of the disease becoming chronic. This means that the virus remains in the body after the acute, short-term disease is over, and may or may not cause further illness.

Some patients have no symptoms of chronic hepatitis C until years later, when liver damage has developed and the signs of cirrhosis (scarring) begin to appear. Hepatitis C can also lead to liver cancer.

Diagnosis is made through blood tests.

Treatment for chronic hepatitis C involves taking medications prescribed by the physician; avoiding alcohol; and using no supplements or prescription medications without a doctor's clearance. In some cases, a liver transplant will be needed to save the patient's life.

The best prevention is to never share needles, toothbrushes, or other personal care items, and to always practice safe sex. There is no vaccine for hepatitis C.

Rarity: Common

Top Symptoms: fatigue, nausea, muscle aches, loss of appetite, joint pain

Symptoms that never occur with chronic hepatitis c: pain in the lower right abdomen, pain in the lower left abdomen, pain in the upper left abdomen, pain around the belly button

Urgency: Primary care doctor

Ulcerative colitis

Ulcerative colitis is a chronic, long-term inflammatory disease of the gastrointestinal tract, specifically involving ulcers and sores of the large intestine (colon) and the rectum. Ulcerative colitis often begins gradually and worsens over time with periods of remission interspers...

Pancreatic cancer

Pancreatic adenocarcinoma is also called pancreatic exocrine cancer, and means that tumors have begun to grow in the exocrine cells of the pancreas. These cells manufacture the enzymes that help digest fats.

The exact cause of any pancreatic cancer is unknown. Risk factors include smoking; obesity; alcoholism; exposure to certain chemicals; family history of the disease; and pre-existing diabetes, pancreatitis, or cirrhosis of the liver.

Symptoms include jaundice, which is a yellowing of the skin and eyes; dark urine; pale-colored stools; abdominal and/or back pain; loss of appetite; and unintended weight loss.

Diagnosis is made through patient history; physical examination; blood tests; abdominal imaging such as ultrasound or CT scan; and sometimes biopsy of the pancreas or other minor surgical procedure to help make the diagnosis.

Treatment involves a combination of several methods, including chemotherapy; radiation therapy; surgery to remove all or part of the pancreas as well as to help relieve some of the symptoms of the disease; pain management; and psychological support.

Rarity: Rare

Top Symptoms: fatigue, nausea, loss of appetite, diarrhea, unintentional weight loss

Urgency: Primary care doctor

Celiac disease

Celiac disease is also called gluten-sensitive enteropathy, coeliac, or sprue. It is an autoimmune response in the gut to gluten, a protein in wheat, rye, and barley.

  • Repeated exposure to gluten causes damage to the lining of the small intestine.

Most at risk are Caucasians with:

  • Family history of celiac disease.
  • Down syndrome.
  • Type 1 diabetes.
  • Rheumatoid arthritis.
  • Autoimmune thyroid disease.

Symptoms include digestive upset with gas, bloating, and diarrhea. The malnutrition causes fatigue, weight loss, fragile bones, severe skin rash, mouth ulcers, anemia, and damage to the spleen and nervous system.

A swollen belly, failure to thrive, muscle wasting, and learning disabilities are seen in children, and normal growth and development can be severely affected.

Diagnosis is made through blood testing and endoscopy, and sometimes biopsy of the small intestine.

There is no cure for the condition, but celiac disease can be managed by removing all gluten from the diet. Nutritional supplements will be used and sometimes steroid medication is given to help heal the gut.

Rarity: Rare

Top Symptoms: fatigue, stomach bloating, nausea, constipation, diarrhea

Urgency: Primary care doctor

Cystic fibrosis

Cystic fibrosis (CF) is an inherited disease of the mucus and sweat glands, affecting multiple organs, especially the lungs. The mucus clogs the lungs, causing breathing problems and making it easy for bacteria to grow. This can lead to problems such as repeated lung infections and lung damage.

Rarity: Rare

Top Symptoms: shortness of breath, productive cough, salty-tasting skin, decreased exercise tolerance, recurring problem with leaking urine

Urgency: Primary care doctor

Diabetes insipidus

Diabetes insipidus (DI) is caused by a lack of, or decreased sensitivity to the hormone vasopressin. Vasopressin is needed for the kidneys to concentrate urine, making sure you do lose to much fluids. If this function is impaired, it will result in urinating frequently and large amounts, extreme thirst and dehydration.

Rarity: Rare

Top Symptoms: fatigue, irritability, constipation, excesive thirst, dry mouth

Urgency: Primary care doctor

Acute pancreatitis

Acute pancreatitis is the inflammation of the pancreas, which creates and releases insulin and glucagon to keep the sugar levels in your blood stable. It also creates the enzymes that digest your food in the small intestine. When these enzymes accidentally get activated in the pancreas, they digest the pancreas itself, causing pain and inflammation.

Rarity: Rare

Top Symptoms: constant abdominal pain, nausea or vomiting, being severely ill, severe abdominal pain, fever

Symptoms that always occur with acute pancreatitis: constant abdominal pain

Urgency: Hospital emergency room

Treatments for foul smelling stool

At-home treatments for foul-smelling stool

If you are having problems with very foul-smelling stool, you may want to try some of the following courses of action.

  • Probiotics: Often, imbalanced gut bacteria cause foul-smelling stools. Probiotics are one easy way to rebalance the gut bacteria and get stools back to normal.
  • Drinking more water: Staying fully hydrated keeps things moving through the system and aids in digestion and the absorption of nutrients from your food.
  • Eat fibrous foods: Eating foods rich in fiber like fruits and vegetables helps to clean out the colon and regulate gut bacteria.
  • Keep a food diary: You might just have a food allergy if you have persistent foul-smelling stools. Watch and see if the odor is most present after you eat or drink certain foods and beverages such as dairy, carb-rich foods, or wheat. You may have lactose intolerance or another food allergy at work such as gluten or carbohydrate intolerance.
  • Eat more naturally probiotic foods: Foods like fermented foods and yogurts can help you regulate gut bacteria and keep the system cleansed and balanced. Try eating more fun foods like kim chi, kefir, sauerkraut, pickles, or adding a little apple cider vinegar to your salads.
  • Eat magnesium-rich foods: Magnesium deficiency can cause foul-smelling stools. Try eating foods rich in magnesium to see if this clears up your problem. Some of the foods highest in magnesium include nuts, pumpkin seeds, sesame seeds, and dark, leafy greens like kale, radicchio, beet greens, Swiss chard, mustard greens, and spinach.
  • Don't smoke or drink alcohol for a while: Tobacco and alcohol can pollute the body and cause certain foods to ferment in the gut, leading to foul-smelling stools.
  • Proper food preparation: Often, bacterial infections of the gut are caused by simple food mishandling. Make sure you fully seal meats in plastic zip-lock bags or containers so that it cannot contaminate all the food in your refrigerator. Make sure you cook all meat and poultry to a proper internal temperature and measure with a meat thermometer. Many people never cook their chicken or casseroles containing meat to a proper temperature of 165 degrees Fahrenheit, for example, which can lead to intestinal infection.

When to see a doctor for foul-smelling stool

If foul-smelling stools are persistent see your physician, who can help you diagnose and treat any underlying conditions.

FAQs about foul smelling stool

Here are some frequently asked questions about foul-smelling stool.

Can GERD cause foul-smelling stool?

The most common symptoms of gastroesophageal reflux disease (GERD) are heartburn and vomiting. Vomiting can be either into the mouth or enough to fill the mouth. GERD is also known for causing difficulty or discomfort while swallowing, chest pain, the sensation of food stuck in the throat, a chronic cough and sometimes nausea. Foul-smelling stool and stomach area pain are more indicative of either a change in diet or an issue beyond the stomach in the intestines.

When should you see a doctor for foul-smelling stool?

Any long-lasting change in stool should be brought up to a primary care physician. It is especially important to go to the doctor if you have blood in your stool, long-standing liquid stools, thin pencil-shaped stools, or a complete stoppage of stools for greater than three days.

Can anxiety lead to foul-smelling stool?

Anxiety does not lead to foul-smelling stool. Foul-smelling stool is produced by either an ingested substance that when digested produces a foul odor or a substance that is not properly digested, and in a semi-digested state produces a foul odor. Anxiety can lead to a loss of bowel incontinence in extreme cases, but it usually does not change the odor and quality of the stool.

Why does my infant have foul-smelling stool?

Infants may have foul-smelling stool for a variety of reasons. Because infants are younger, their foul-smelling stool could be a manifestation of a gastrointestinal deficiency like celiac disease, cystic fibrosis, or a vitamin deficiency in their feeding. It is important to know when this foul stool began, to note any color changes, and to note the frequency of stool production for your child's pediatrician at your next visit. Foul-smelling stool may also be a sign of infection (e.g. Giardia) which may be treated with a simple antiparasitic drug.

What foods lead to foul-smelling stool?

Foul-smelling stool can be caused by diets high in meat, high in dairy, and high in sugar. High-meat diets or diets that are high in sulfur (which includes vegetables like broccoli, cabbage, and kale) can all cause a sulfuric or foul smell in your feces. Milk can also cause constipation, loose stools, and an increase in gas as the lactose that is not digested is digested by gut bacteria that produce foul-smelling gases.

Questions your doctor may ask about foul smelling stool

  • Have you experienced any nausea?
  • Have you been feeling more tired than usual, lethargic or fatigued despite sleeping a normal amount?
  • Any fever today or during the last week?
  • Have you had any changes in your weight?

Self-diagnose with our free Buoy Assistant if you answer yes on any of these questions.

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  1. Malabsorption. International Foundation of Gastrointestinal Disorders. Updated Sept. 1, 2015. IFFGD Link
  2. Stools - foul smelling. U.S. National Library of Medicine: MedlinePlus. Updated April 1, 2019. MedlinePlus Link
  3. Symptoms & Causes of Diarrhea. National Institute of Diabetes and Digestive and Kidney Diseases. November 2016. NIDDK Link
  4. Probiotics: In Depth. National Center for Complementary and Integrative Health. Updated July 31, 2018. NCCIH Link
  5. Symptoms of Celiac Disease. Celiac Disease Foundation. Celiac Link
  6. Magnesium. National Institutes of Health. Updated Sept. 26, 2018. NIH Link
  7. Giardiasis. Johns Hopkins Medicine. Johns Hopkins Medicine Link