Foul-Smelling Gas

What Causes Foul-Smelling Flatulence?

Foul-smelling flatulence can have various causes, ranging in severity from 'minor' to 'needs attention'.  Finding the true cause means ruling out or confirming each possibility – in other words, diagnosis.

Diagnose your symptoms now!
  • check your overall health status
  • learn what you should be doing right now
  • identify any nutritional deficiencies

Diagnosis is usually a complex process due to the sheer number of possible causes and related symptoms.  In order to diagnose foul-smelling flatulence, we could:

  • Research the topic
  • Find a doctor with the time
  • Use a diagnostic computer system.
The process is the same, whichever method is used.

Step 1: List all Possible Causes

We begin by identifying the disease conditions which have "foul-smelling flatulence" as a symptom.  Here are four possibilities:
  • Carbohydrate Intolerance
  • Enteritis
  • Gastroenteritis
  • Lactose Intolerance

Step 2: Build a Symptom Checklist

We then identify all possible symptoms and risk factors of each possible cause, and check the ones that apply:
meal-related bloating
bloating caused by many foods
regular episodes of diarrhea
Asian ethnicity
African ethnicity
frequent episodes of diarrhea
recent onset vomiting
frequent unexplained vomiting
having watery stools
having a moderate fever
acute abdominal pain
chronic diarrhea
... and more than 10 others

Step 3: Rule Out or Confirm each Possible Cause

A differential diagnosis of your symptoms and risk factors finds the likely cause of foul-smelling flatulence:
Cause Probability Status
Lactose Intolerance 96% Confirm
Enteritis 28% Unlikely
Carbohydrate Intolerance 5% Ruled out
Gastroenteritis 0% Ruled out
* This is a simple example to illustrate the process

Arriving at a Correct Diagnosis

The Analyst™ is our online diagnosis tool that learns all about you through a straightforward process of multi-level questioning, providing diagnosis at the end.

In the Gastrointestinal Symptoms section of the questionnaire, The Analyst™ will ask the following question about foul-smelling gas:
When you pass gas ("fart"), how does it usually smell?
Possible responses:
→ Don't know / it varies a lot / don't want to know!
→ Usually odorless
→ Usually about 'normal' / 'noticeable'
→ It varies between 'normal' and terrible
→ Usually terrible / people run away screaming
Based on your response to this question, which may indicate odorless flatulence, 'normal'-smelling flatulence, foul-smelling flatulence or very foul-smelling flatulence, The Analyst™ will consider possibilities such as:

Infections of the digestive tract can lead to foul-smelling flatulence.  There are many different bacteria and viruses that can cause infections in the lining of the digestive tract.  Some of these may be associated with traveling to different parts of the world; infections are usually accompanied by gas, diarrhea, fever, and abdominal pain.

Lactose Intolerance

Lactose is the sugar found in dairy products.  When we don't have enough of the enzyme necessary to break down lactose, it remains in our digestive tract for odor-causing bacteria to feed on.

Concerned or curious about your health?  Try The Analyst™
Symptom Entry
Symptom Entry
Full Explanations
Optional Doctor Review
Review (optional)
We use cookies for traffic analysis, advertising, and to provide the best user experience