Read below about foul smelling stool, including causes, treatment options and remedies. Or get a personalized analysis of your foul smelling stool from our A.I. health assistant. At Buoy, we build tools that help you know what’s wrong right now and how to get the right care.

A.I. Health Assistant

Take a quiz to find out why you’re having foul smelling stool

Take a quiz

Foul Smelling Stool Causes Overview

Changes in diet can often affect the odor of one's stool. Pigging out on street Mexican food, for example, can overwhelm the gut bacteria and lead to 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.

2 Potential Foul Smelling Stool Causes

Disclaimer: The article does not replace an evaluation by a physician. Information on this page is provided as an information resource only, and is not to be used or relied on for any diagnostic or treatment purposes.

  1. 1.Lactose Intolerance

    Lactose intolerance is the inability to fully digest a sugar (lactose) in milk. This results in discomfort, gas, and maybe even stool changes shortly after ingesting a dairy product.


    Top Symptoms:
    fatigue, abdominal pain (stomach ache), stomach bloating, constipation, diarrhea

    Foul Smelling Stool Checker

    Take a quiz to find out why you’re having foul smelling stool.

    Take a quiz
  2. 2.Intestinal Infection by Giardia Parasite

    Some intestinal illnesses are caused by parasitic infection. People can become infected if they swallow or swim in contaminated water or are exposed to infected feces.

    With proper treatment, symptoms will last no longer than 2 weeks.

    Top Symptoms:
    fatigue, nausea, stomach bloating, loss of appetite, diarrhea
    Symptoms that never occur with intestinal infection by giardia parasite:
    Primary care doctor

Foul Smelling Stool Treatments and Relief

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.

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

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

If you've answered yes to one or more of these questions, try our foul smelling stool symptom checker to find out more.

Take a quiz

Foul Smelling Stool Symptom Checker Statistics

  • People who have experienced foul smelling stool have also experienced:

    • 12% Diarrhea
    • 9% Abdominal Pain (Stomach Ache)
    • 7% Stomach Bloating
  • People who have experienced foul smelling stool were most often matched with:

    • 6% Lactose Intolerance
    • 4% Intestinal Infection by Giardia Parasite
  • Source: Aggregated and anonymized results from visits to the Buoy AI health assistant (check it out by clicking on “Take Quiz”).

A.I. Health Assistant

Take a quiz to find out why you’re having foul smelling stool

Take a quiz