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Flatulence and wind

Medical Professionals

Professional Reference articles are designed for health professionals to use. They are written by UK doctors and based on research evidence, UK and European Guidelines. You may find the Trapped wind, gas and bloating article more useful, or one of our other health articles.

Flatulence and wind are symptoms related to gas in the gastrointestinal (GI) system. 'Flatulence' usually refers to gas passed per rectum. 'Wind' as a symptom may mean either belching (gas passed from the stomach outwards via the mouth - also called 'eructation') or gas passed per rectum (or even just feeling bloated).

Flatulence and belching are common symptoms in the general population.

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Normal physiology

Belching

This is the release of gas from the stomach, either voluntary or involuntary. It is a normal reflex which occurs most commonly after meals, releasing swallowed air.

There may be two types of excessive belching:

  • Supragastric belching, where air is sucked into and expelled from the pharynx only.

  • Aerophagia, where there is excess swallowing of air into the stomach.

Flatulence

  • Intestinal bacterial colonies produce gases. Carbon dioxide, hydrogen and methane are responsible for the main volume of intestinal gas and sulfur-containing gases for malodour.

  • The volume and composition of gas depends both on diet and on colonic flora.

  • People with irritable bowel syndrome (IBS) are likely to produce a greater volume of gas than people who do not have IBS.

Aetiology

Belching

  • Diet/lifestyle factors - eg, eating too quickly, fizzy drinks, chewing gum, smoking.

  • Antacids - produce carbon dioxide gas which may contribute.

  • Dyspepsia or reflux - patients may swallow air and may belch in an attempt to relieve upper GI symptoms.

  • Giardiasis - can cause malodorous belching.

Flatulence

Symptoms may be due to excessive volume of gas or to malodour. Possible causes or contributing factors are:

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Assessment

  • Clarify what most bothers the patient about their symptoms.

  • 'Red flags' - eg, dysphagia, weight loss, rectal bleeding, change in bowel habit with looser stools in patients aged >60 years, family history of bowel cancer1.

  • Clinical examination (if relevant) to look for any serious signs - eg, anaemia, nodes and abdominal, pelvic or rectal masses.

Investigations

These depend on the clinical picture. Basic tests may be relevant to help rule out other problems (eg, as recommended in the diagnosis of IBS)1:

Breath tests may be used to assess intestinal flora and small intestinal bacterial overgrowth, usually in the context of research studies.

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Management

Belching

  • Explanation of normal physiology and reassurance may be sufficient.

  • Investigate/treat dyspepsia and reflux symptoms if relevant.

  • Speech therapy or behavioural therapy may be used.

Flatulence

Note that most of the research and literature on this topic relate to patients diagnosed with IBS. Possible treatments are:

  • Mild physical activity - has been shown to enhance gas clearance in a study of patients with bloating.

  • Treating exacerbating factors such as constipation.

  • Diet:

    • Soluble fibre such as linseed (up to one tablespoon daily) and oats1.

    • Diets low in fermentable carbohydrate can reduce flatulence in IBS.

  • Probiotics:

    • These are 'gut-friendly' bacteria such as lactobacilli and bifidobacteria.

    • Their mechanism of action is unclear but they can alter colonic fermentation and inhibit gas-producing bacteria such as Clostridium spp. They have an effect on intestinal motility and may also have an anti-inflammatory effect on mucosal cells.

    • They have been shown to modestly reduce symptoms in patients with IBS2.

    • The specific strain of bacteria may be important but, on current evidence, it is difficult to advise which strain(s) to use.

  • Medications:

    • Antibiotics (eg, metronidazole or rifaximin) can be used to treat small intestinal bacterial overgrowth3.

    • Simeticone combined with loperamide may improve gas symptoms in acute diarrhoea.

    • Oral bismuth subsalicylate binds sulfide gases in the gut but is not safe for regular use due to the salicylate content.

  • Supplements:

    • Alpha-galactosidase, an enzyme supplement, has been shown to reduce flatus after eating beans, but there is insufficient evidence to support its regular use4.

  • Odour reduction devices:

    • Garment devices containing activated charcoal have been tested in one trial5. This found that briefs containing charcoal were effective, but pads and cushions of the same material were less helpful.

Further reading and references

  • Bendezu RA, Mego M, Monclus E, et al; Colonic content: effect of diet, meals, and defecation. Neurogastroenterol Motil. 2017 Feb;29(2). doi: 10.1111/nmo.12930. Epub 2016 Aug 21.
  • Malagelada JR, Accarino A, Azpiroz F; Bloating and Abdominal Distension: Old Misconceptions and Current Knowledge. Am J Gastroenterol. 2017 Aug;112(8):1221-1231. doi: 10.1038/ajg.2017.129. Epub 2017 May 16.
  1. Irritable bowel syndrome in adults: diagnosis and management of irritable bowel syndrome in primary care; NICE Clinical Guideline (February 2008, updated April 2017)
  2. Dale HF, Rasmussen SH, Asiller OO, et al; Probiotics in Irritable Bowel Syndrome: An Up-to-Date Systematic Review. Nutrients. 2019 Sep 2;11(9). pii: nu11092048. doi: 10.3390/nu11092048.
  3. Melchior C, Gourcerol G, Bridoux V, et al; Efficacy of antibiotherapy for treating flatus incontinence associated with small intestinal bacterial overgrowth: A pilot randomized trial. PLoS One. 2017 Aug 1;12(8):e0180835. doi: 10.1371/journal.pone.0180835. eCollection 2017.
  4. Hillila M, Farkkila MA, Sipponen T, et al; Does oral alpha-galactosidase relieve irritable bowel symptoms? Scand J Gastroenterol. 2016 Jan;51(1):16-21. doi: 10.3109/00365521.2015.1063156. Epub 2015 Jul 2.
  5. Ohge H, Furne JK, Springfield J, et al; Effectiveness of devices purported to reduce flatus odor. Am J Gastroenterol. 2005 Feb;100(2):397-400.

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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