What Is Intestinal Gas?


Have you ever been in a situation where you belched in a public area and were embarrassed by it? But what is intestinal gas? Intestinal gas is the air trapped in the digestive or gastrointestinal tract. (It is completely natural to harbour some amount of gas), which is normally eliminated through the mouth, and this is called belching or burping. It can also happen through flatulence which is the passage of gas through the rectum. You can imagine pumping water through an unused water hose; the air trapped would be released, followed by the water. Did you know that an average person releases 0.6–1.8 litres of gas each day?

This expulsion of gas can also be a result of the presence of some conditions such as lactose intolerance, gastritis, and some gastrointestinal autoimmune conditions such as Inflammatory. 

Bowel Disease (IBD), which includes Crohn’s Disease and Ulcerative Colitis, and Irritable Bowel Syndrome (IBS), are among a few1,6

What does intestinal gas contain? 

The (composition of intestinal gas) is a mixture of gases produced throughout digestion such as nitrogen, oxygen, carbon dioxide, hydrogen, and methane. Sometimes, bacteria in the large intestine like (Klebsiella and Escherichia coli), produce (hydrogen sulphide), the gas primarily responsible for the displeasing and uncomfortable smell after flatulence.2,5 The percentage of these gases may vary among individuals mainly because of diet and gastrointestinal disease.

Causes of intestinal gas

There are basically (two main modes of air entry) into the gastrointestinal tract: external or exogenous and internal or endogenous.6

Exogenous: This happens when we take in a volume of air through the mouth or aerophagia. Sometimes, when we use a straw to drink, it draws air inwards, too. Chewing gum and smoking also result in the entry of air. The best example is breathing out carbon dioxide after an intake of carbonated drinks.

  • Endogenous:
    • Gut microbiota:3 Our gastrointestinal tract might look like a simple tube composed of smooth muscle, but is indeed a complex system to understand. The stomach, small intestine, and large intestine are tiny ecosystems that accommodate many species of archaea, bacteria, fungi, and even viruses. This association of microorganisms is known as the (gut microbiota). Few of these are harmful, while some are beneficial. Some examples include bacteria like (Escherichia coli), Helicobacter pylori, and (Lactobacillus species), such as (fungi) like Candida albicans, and Aspergillus species. The notorious bacteria that are responsible for most of the intestinal gas produced are in the large intestine because it is a region in the body that contains less oxygen, and bacteria that do not need oxygen to survive (anaerobes), are the popular inhabitants. Some bacteria that live in the colon, the first part of the large intestine, include methane-producers like Methanobrevibacter and butyric acid-producers like Clostridium2,4 
  • Macromolecular digestion:
    • Carbohydrates:  As mentioned earlier, these gases are the by-products of digestion, which is essentially the breakdown of big molecules into small, simple ones. When small carbohydrates or sugars like oligosaccharides (carbohydrates like lactose with 3–10 repeating units or monomers of monosaccharides like glucose, galactose, and fructose. Lactose, the milk sugar, is made of glucose and galactose) are produced from a substrate during digestion, they pass through the small intestine without any further breakdown to reach the large intestine, where the bacteria in the colon make use of these sugars to produce energy. This happens because our body does not contain the enzymes to disintegrate oligosaccharide 1–6 glycosidic bonds. The vegetables that are known to contain a lot of fibre and produce a high content of oligosaccharides are beans, cabbage, broccoli, cauliflower, Brussels sprouts, and bok choy. Other than beans, which are legumes, the rest of the vegetables are called cruciferous vegetables, which belong to the same plant family of Brassicaceae. Beans are legumes that contain oligosaccharides, such as stachyose and raffinose, that end up getting fermented in the colon by the resident bacteria, which causes gas accumulation. Raffinose is also found in whole grains, asparagus, and cruciferous vegetables. 
    • Fats: Fats are a kind of simple lipids, which are small molecules. When fried food is consumed, a lot of energy is required for its disintegration. While this takes place, a peptide hormone called cholecystokinin (CCK) is produced by the stomach and the small intestine and this slows down the emptying of the stomach, thus reducing hunger. This also results in fermentation, hence, gas production. That is one of the reasons why we feel bloated after a large meal at KFC! 
  • Menstruation:7 The menstrual cycle, commonly known as periods, is also a factor for intestinal gas production due to the fluctuating hormones during this time. The level of estrogen is high during this period due to the production of prostaglandins, which aid in the shedding of the endometrium of the uterus. Prostaglandins also make the smooth muscle more motile, which the uterus and the gastrointestinal tract are made of. This results in the movement of the colon and causes flatulence and altered defecation or pooping.
  • Gastrointestinal disorders:6 One of the classic reasons for intestinal gas. More than 60-70 million of the world’s population suffers from some form of gastrointestinal trouble. 
    • Lactose intolerance: This, being one of the popular conditions, causes individuals to derail the breakdown of lactose into glucose and galactose due to a deficiency or the lack of lactase, which aids the breakdown. The unbroken lactose is then used up by bacteria like Bifidobacterium and Lactobacillus, to produce lactic acid and hydrogen, eventually leading up to a gas buildup
    • Inflammatory Bowel Disease (IBD): This group of chronic autoimmune conditions is caused by the inflammation of various tissues in the digestive tract, mainly affecting the small intestine and large intestine. The two diseases that come under IBD are Crohn’s Disease, which can occur anywhere in the digestive tract but majorly targets the ileum of the small intestine and Ulcerative colitis which mainly targets the colon. Due to tissue inflammation, several activities of the intestine are impaired which results in the accumulation of intestinal gas
    • Gastroesophageal Reflux Disease (GERD): It is also called acid reflux in layman's terms. It can sometimes lead to chronic belching and can sometimes indicate peptic or stomach ulcers
    • Meganblase syndrome: It causes chronic burping and shortness of breath, through intense air swallowing after heavy meals
    • Intestinal motility disorders: One of them is Irritable Bowel Syndrome leads to intestinal gas. Intestinal motility disorders are not that well understood

Signs and symptoms of intestinal gas

The most common symptoms would include rapid and persistent belching and flatulence caused due to bloating. Some abdominal pain is also caused due to the accumulation of gas, and in worse cases, cramps and heartburns are felt as well. Intestinal hernial presence can be a cause for the accumulation of gas. In cases of (constipation) when an individual is not able to complete defecation, it enables the faecal bacteria to stay longer inside the abdomen to cause pain and flatulence.6

Management and treatment for intestinal gas

  1. Diet: Intestinal gas can be controlled through diet alterations. People suffering from lactose intolerance must reduce their intake of dairy milk and its products and move to other options such as lactose-free milk or plant-based milk like almond milk and soy milk and the products obtained from them like cheese. Products that contain lactase can be used if dairy is being consumed. Vegetables like beans, cabbage, cauliflower, Brussels sprouts, broccoli, bok choy, and whole grain intake can be reduced. To take notes of how your body reacts to each kind of food, a food diary can be maintained
  2. Lifestyle: Heavy meals at night can be avoided since digestive activity is the least at this time of the day. After meals, people can walk for short distances to ease the fullness of the abdomen. Drinking excessive amounts of water reduces digestive activity as well, and is advised to reduce it

For treatment, the most widely used medicines are antacids like pepto-bismol, known as bismuth subsalicylate. However, the prolonged use of these medicines would only suppress intestinal gas and not provide complete relief in cases where it is a symptom and not a minor trouble. It is always advised to visit the doctor immediately in cases of chronic cases of gas trouble.6


The most popular method for diagnosis would be taking an abdominal X-ray. In cases of prolonged signs and symptoms, a Computed Tomography scan (CT scan) is advised, which would check for any inflammation or other abnormalities.

Colonoscopy is also sometimes carried out in cases of chronic cases. This method involves the usage of a long and flexible tube with an illuminated end, which is passed into the rectum to obtain a full view of the scene inside the digestive tract. This procedure involves the cleaning of the rectum with polyethene glycol electrolyte solution (PEG-ES) to remove any faecal matter for better visualization. 

Sigmoidoscopy can be done as well. It involves the use of a sigmoidoscope, which releases air into the large intestine to inflate it for a better picture.


The main complication would be anxiety, and social embarrassment due to continuous and frequent belching or flatulence. But intestinal gas can be better perceived as a symptom, for which the underlying cause is usually some gastrointestinal or other disorder.


How can I prevent intestinal gas?

Focus on your dietary options and reduce the intake of sugar-free food, because they tend to contain sorbitol that causes gas. Reduce eating vegetables like beans, cabbage, cauliflower, Brussels sprouts, broccoli, bok choy, onions, etc. If you are lactose intolerant, try out lactose-free or vegan options to compensate for the dairy intake.

How common is intestinal gas?

Everybody has gas in their digestive tract. The trouble starts only when it is in excess and causes pain and discomfort.

Who is at risk of intestinal gas?

People with chronic digestive issues, people who smoke excessively, those who have heavy meals and do not exercise, people who swallow a large volume of air after meals, or even individuals who sleep with their mouths open are at a higher risk.

When should I see a doctor?

You must immediately visit the doctor if you face intestinal gas for a long time and if it is frequent. If weight loss, frequent acidity, heartburn, mucus, and/or blood is also passed while defecating or pooping, it indicates a serious issue. 


Intestinal gas is the buildup of gas obtained from the by-products of digestion, gut microfloral metabolism, or due to bad lifestyle choices like swallowing air or sleeping with the mouth open. Everybody harbours some amount of gas in their gastrointestinal tract and this is completely normal until the expulsion of gas is frequent and accompanied by abdominal pain and cramps. This gas is expelled either by belching/burping or flatulence. It is usually regarded as a symptom rather than terming it as a disorder since gas is usually an important symptom of many gastrointestinal conditions and kidney diseases.  Chronic intestinal gas is an essential indication of many chronic gastrointestinal issues such as Gastroesophageal Reflux Disease (GERD), Inflammatory Bowel Disease, Irritable Bowel Syndrome, and lactose Intolerance to list a few, or it can also indicate that your diet has been altered and must be revised. 


  1. Thursby E, Juge N. Introduction to the human gut microbiota. Biochem J [Internet]. 2017 Jun 1 [cited 2023 Jun 22];474(11):1823–36. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5433529/
  2. Canny GO, McCormick BA. Bacteria in the intestine, helpful residents or enemies from within? Infect Immun [Internet]. 2008 Aug [cited 2023 Jul 10];76(8):3360–73. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2493210/
  3. Hallen-Adams HE, Suhr MJ. Fungi in the healthy human gastrointestinal tract. Virulence [Internet]. 2016 Oct 13 [cited 2023 Jul 10];8(3):352–8. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5411236/
  4. Mutuyemungu E, Singh M, Liu S, Rose DJ. Intestinal gas production by the gut microbiota: A review. Journal of Functional Foods [Internet]. 2023 Jan 1 [cited 2023 Jul 10];100:105367. Available from: https://www.sciencedirect.com/science/article/pii/S1756464622004376
  5. Murros KE. Hydrogen sulfide produced by gut bacteria may induce Parkinson’s disease. Cells [Internet]. 2022 Mar 12 [cited 2023 Jul 10];11(6):978. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8946538/
  6. Hasler WL. Gas and bloating. Gastroenterol Hepatol (N Y) [Internet]. 2006 Sep [cited 2023 Oct 9];2(9):654–62. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5350578/
  7. Bernstein MT, Graff LA, Avery L, Palatnick C, Parnerowski K, Targownik LE. Gastrointestinal symptoms before and during menses in healthy women. BMC Womens Health [Internet]. 2014 Jan 22 [cited 2023 Oct 9];14:14. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3901893/
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Dharshana Guru Raghavendran

MSc. Infection, Immunity and Infectious Disease - University of Leeds, United Kingdom

Dharshana is a researcher in the field of immunology. She’s especially passionate about studying auto-immune conditions, hypersensitivity, and gastrointestinal disorders.

Dharshana is also an experienced scientific communicator and has helmed many research projects as well as management roles.

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