Dealing with gas

Why do I have gas? What can I do about it?

The average person makes between 500ml-1500ml of gas per day, and passes gas at least 10 times per day.

Gas is a normal part of digestion, and is found throughout the digestive tract, from the mouth to the rectum.

Gas in the stomach and upper intestine usually results from swallowing air. Excess gas in the stomach or upper intestine will result in burping or belching.

Causes of swallowing air include:

  • chewing gum
  • talking while eating
  • drinking with a straw
  • drinking carbonated beverages

Excess gas in the lower intestine or colon will result in gas being passed through your anus or colostomy.

Lower intestinal gas is a normal by-product of digestion.  Bacteria in the gastrointestinal (GI) tract react with the food to produce hydrogen, carbon dioxide and sometimes methane.

Some foods that cause gas include:

  • Beans and lentils
  • Dairy products containing lactose
  • Fructose and sorbitol (artificial sweeteners)
  • Digestive disorders such as celiac disease, irritable bowel syndrome, lactose intolerance, etc.

Reduce swallowed air by:

  • avoiding gum and sucking on hard candies,
  • avoiding carbonated drinks,
  • ensuring dentures fit correctly
  • eating slowly

Make dietary changes:

  • Eat less of the foods that give you gas. This varies from person to person.


  • Beano (alpha-galactosidase) is an over-the-counter digestive aid which contains a sugar-digesting enzyme that the body lacks to digest sugars in beans and many vegetables. Beano has no effect on gas caused by lactose or fibre, just gas caused by beans and many vegetables.
  • Simethicone (Gas-X or Mylanta Gas) assists in making large gas bubbles smaller and easier to pass (this only works for people with a large intestine).
  • Lactase tablets or drops can help people with lactose intolerance to digest milk products.

Gas and an ostomy

Immediately after bowel surgery, the intestine has been disturbed and makes lots of gas. This will settle down as the bowel settles, and normal diet and activities are resumed.

People with an ileostomy will always have some gas going into the pouch. Right after surgery there may be a lot of gas. As the bowel settles the amount of gas will go down. Eating a normal diet on a regular schedule will also help reduce the amount of gas.

Stool from an ileostomy tends to be wet. The moisture prevents the filters in pouches from working well. Many people with an ileostomy decide the filter is not necessary for them.

People with a colostomy will have some gas. Gas is made when the normal healthy bacteria in the colon, or large intestine, eat the digested food residue that goes into the colon as part of digestion. People with a colostomy still have most of their large intestine.

Ostomy pouches are manufactured with filters that deodorize as they vent gas out of the pouch. Get a sample from your Nurse Specialized in Wound, Ostomy & Continence (NSWOC), your ostomy supplier, or the manufacturer to see if filters work for you.