Foul-smelling stools? How to stop the funk.

Why does my poop stink?

Everyone poops, and yes, everyone’s poop does stink. But how smelly your poop gets depends on the bacteria in your gut.

Stools form in your colon (ready for evacuation), which is full of bacteria. The types of food you eat will determine the types of bacteria present. Different bacteria types all produce their own unique array of gases. These different gases then determine how your poop smells.

What if I have extra-smelly poop?

Does your poop have your housemates investing in gas masks or your family running for the nearest exit? There are some lifestyle factors that can contribute to foul-smelling stools, including:


  • Having a big night ─ Drinking a lot of alcohol can alter the motility, permeability and bacteria of the gut, causing loose stools or diarrhoea and a change in the odour of your stool.
  • Some medications Some medications, like antibiotics, can alter the bacteria in your gut and change the smell of your stool.
  • Lactose intolerance Could you be lactose intolerant? If you eat dairy and you’re lactose (a sugar in dairy) intolerant, this lactose won’t be absorbed by the intestine, causing an odorous runny stool.
  • Your diet ─ High-fat diets or diets where you are eating things like sorbitol as a sugar replacement can influence the smell of your poop. Foods high in sulfur like onion, garlic and cabbage can also change the smell of your stool.

There may also be an underlying medical cause of a foul-smelling stool, so it is recommended you see your GP if you have:


  • Black or pale stools, often
  • Blood in the stool
  • Changes in the stool that you think is related to what you eat, e.g. runny stools after drinking milk
  • Chills
  • Cramping
  • Fever
  • Pain in the abdomen
  • Unexplained weight loss

Your GP will ask questions about your stools, particularly if there have been any recent changes to your stools or your diet and any other symptoms.

Your doctor might also request a sample of your stool.

Having the occasional stinky stool happens and may be attributed to something in your diet, but if you find your stinky stools continuing, visit your GP to rule out any underlying medical conditions.


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