What Causes Bad Smelling Flatulence?

Before we explore the causes of

bad smelling flatulence

, it is important to understand what flatulence is. Flatulence is the discharge of gases through the anus. Intestinal gas is the end result of the digestive process and on analysis revealed a number of chemically relevant gases in it. This composition of the various gases is also referred to as ai???flatusai??i??. Socially, the expulsion of bodily gases through the bottom can call for a lot of embarrassment. The latter would also be referred to as farting. The noises associated with farting are caused by the vibration of the anal sphincter muscle and by a closed and constricted bum.

Composition of bad smelling flatulence

The major components of flatus in general are as follows:

  • Nitrogen 20-90%
  • Hydrogen 0-50%
  • Carbon Dioxide 10-30%
  • Oxygen 0-10%
  • Methane 0-10%

The bad smell however arises from sulfur containing compounds like methanethiol, hydrogen sulfide (rotten egg smell) and dimethyl sulfide. Having odor causing compounds in intestinal gas is more when a plant based diet is opted for.

Causes of bad smelling anal gas

  • Increased swallowing of air while eating, drinking, yawning or having an acid reflux etc can result in intestinal gas being build up.
  • When food is not broken down properly and digested well in the stomach and small intestine, it reaches the large intestine and is further acted upon by the intestinal bacteria, yeast and prokaryotes. Presence of excess microflora bacteria in the intestine can cause it.
  • Foods which have a polymeric carbohydrate structure (polysaccharides) are the ones mostly held responsible for gas. Foods like beans, lentils, garlic, dairy products, wheat, turnip, radishes, sweet potato, potato etc fall in this category. Cruciferous vegetables like cauliflower, broccoli, cabbage etc causes flatulence which is generally smelly.
  • Inability to defecate properly and retention of feces in the anus can cause bad smelling intestinal gas.
  • In cases of individuals with lactose intolerance, gut bacteria feeds on the undigested dairy products in the large intestine and causes bad odorous gas.
  • Intestinal diseases like giardiasis is known to be associated with

    bad smelling flatulence


  • Mental and physical stress have also been linked with the expulsion of foul smelling bodily gas.


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