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Got gas? Let's explore symptoms, causes and relief

A smiling young man in a lift surrounded by four people holding their noses

Burps, belches, eructation, wind, flatulence, farts—there are many names for emitting gas, and yep, we all do it, many times a day, consciously or not.

The average human can create more than 2 litres of gas a day.

All this gas needs to get out of your body somehow. It has two main escape routes—from your upper digestive tract out through your mouth (burping), or from your lower digestive tract, out through your anus (flatulence or passing wind).

The odd burp or wind is completely normal but can sometimes be very socially awkward such as unexpectedly letting rip while doing squats in the gym.

Where does all this gas come from? What’s in it? Is it healthy? Can it be a sign something is not right?

All about gas

In the upper digestive tract, the main cause of gas (in healthy people) is swallowing air, and in the lower digestive tract, it's bacteria helping to digest your food in your large intestine.

People swallow air (mostly nitrogen, oxygen and carbon dioxide) by eating or drinking too quickly, chewing gum, sucking on sweets and candies, talking while eating, drinking fizzy drinks, drinking through straws, or smoking. (There are a few other causes, such as aerophagia, which is a nervous habit where people swallow air.)

Most of that air will be burped out, but it shouldn’t be surprising that not burping can cause flatulence. That swallowed air must emerge somewhere.

People pass wind anywhere from 7 to 12 times or more a day.

The main source of gas in the lower digestive system in healthy people is the digestion of food. Undigested food moves from your small intestine to your large intestine where it is broken down further by helpful or ‘good’ bacteria. This process makes gas – usually hydrogen, carbon dioxide and methane.

This gas naturally escapes as flatulence or wind, as it is produced closer to the nether regions. It usually doesn’t have much smell, thank goodness.

But sulphur rich foods, such as onions, cabbage, meat, nuts and legumes can make the gas smelly. Some bacteria make hydrogen sulphide, a very smelly sulphurous gas that gives volcanoes their distinctive hellish smell. This will ensure your wind gets noticed.

Certain types of foods are harder for our bodies to digest, and this can vary person to person, and can result in the old schoolyard chant, Beans, beans musical fruit. The more you eat the more you toot being surprisingly accurate (although some beans have been bred or modified to be less gas-inducing).

Which foods are most likely to cause gas?

  • Beans and lentils
  • Broccoli, cauliflower, brussels sprouts, cabbage, and onions
  • Whole-grain foods such as cereals, breads, and crackers
  • Sugars found in fruit and juices, but also in processed foods containing high-fructose corn syrup
  • Sugars and some artificial sweeteners found in diet drinks and foods.

Could gas be a sign of a medical problem?

Yes, gas, particularly if excessive, or combined with other symptoms, can indicate possible medical conditions, some serious.

There is a bit of variability in how often and how much people burp or pass wind, but if for example you are passing wind 50 times a day or more, or it’s a lot more than usual, or you are burping excessively, and these are combined with any other symptoms such as bloating, abdominal pain, heartburn, problems swallowing, unintentional and unexplained weight loss, ulcers, bloody vomit, black vomit that resembles coffee grounds, bloody stool, tarry black stool, or other symptoms, it can indicate potentially serious conditions such as:

You should not ignore any of these. Seek medical advice.

Sugars known as FODMAPS (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) are sugars that are poorly absorbed by the small intestine and can trigger symptoms of irritable bowel syndrome (IBS) in some people. This can cause bloating, abdominal pain, nausea, constipation and flatulence. A low FODMAP diet can reduce or remove foods from the diet to avoid these symptoms.

Some of these high FODMAP foods are:

  • garlic
  • onions
  • apples
  • green peas
  • some marinated meats
  • dairy products (e.g., milk, yoghurt)
  • chickpeas
  • wheat, barley and rye-based bread

Other food intolerances, such as lactose or gluten intolerance can also cause flatulence. Try to notice if certain foods cause problems for you and cut down on those or eliminate them and find alternatives. Keeping a food diary can be helpful.

Gas can also be caused by other gut problems such as constipation, or diarrhoea. If these are severe, or ongoing, you should talk to your doctor.

Prevention and treatment

Because swallowing air is the main cause of burping from excess gas in healthy people, you can train yourself to swallow less air by eating and drinking more slowly, cutting out chewing gum and hard candy, avoiding fizzy drinks, not drinking through straws, trying not to talk excessively while you eat or drink, and stopping smoking.

For food-related bloating and gas, keeping a food diary and avoiding food that seems to cause it can be a big help. For some people this may mean you’re not getting adequate nutrition, so you should talk to your doctor if you’re cutting out foods.

There are some over-the-counter products and medicines available that can help counteract some intolerances such as lactose (milk sugar) or bean intolerances and enable people to consume foods that cause them without experiencing excessive gas or bloating.

For example, lactase is an enzyme you can take to help break down lactose if you are lactose intolerant and have consumed (or are planning to consume) something containing lactose, such as milk. There are also milk substitutes without lactose available for people who are lactose intolerant.

Probiotics can help to add good bacteria to your gut and inhibit the growth of bad bacteria.

Antacids can help with excessive burping and mild or occasional reflux. If your reflux is severe or happens often (more than twice a week) or has other symptoms, you should see your doctor, as this can be an indication of more serious issues, such as GORD, or a stomach ulcer.

If constipation is an issue, drinking more water and eating a fibre- and water-rich diet may help. Over-the-counter fibre supplements are available. If the constipation is ongoing or severe, see your doctor.

If you have diarrhoea for more than a few days, you should see your doctor.

If your gas is caused by a more serious medical condition, such as a stomach ulcer or gastritis, your doctor may change your diet and prescribe medicine, such as a proton pump inhibitor (which reduces production of stomach acid), or other drugs. In severe cases, surgery may sometimes be recommended.

For more information about over-the-counter products, medication, prevention and treatment options, you should talk to your doctor.

More information

Last updated: 25 February 2022