Flatulence and Wind

Professional Reference articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.

See also: Wind/Gas/Bloating written for patients

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) or gas passed per rectum (or even just feeling bloated). 'Eructation' is another term for belching.

Flatulence and belching are common symptoms in the general population.[1]


  • 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:[2]
    • Supragastric belching, where air is sucked into and expelled from the pharynx only.
    • Aerophagia, where there is excess swallowing of air into the stomach.


  • 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.[3]
  • The volume and composition of gas depends both on diet and on colonic flora.[4, 5]
  • Peope with irritable bowel syndrome (IBS) are likely to produce a greater volume of gas than people who do not have IBS. IBS is also associated with a positive lactulose breath test (a test that assesses the amount of fermented gas generated by bacteria in the bowel) and an increase in gas-related symptoms. This would seem to counteract previous theories that there is no difference in the amount of gas produced by IBS and non-IBS individuals but that non-IBS people are simply more tolerant of large gas volumes.[6]


  • 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.[7]
  • Giardiasis - can cause malodorous belching.[8]


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

  • Diets high in fermentable carbohydrate (eg, pulses, bran and fruit).[3]
  • Variations in bowel flora composition.[4, 5]
  • Constipation.[9]
  • IBS.[10]
  • Acute gastroenteritis.[3]
  • Giardiasis.[8]
  • Small intestinal bacterial overgrowth.[11]
  • Lactose intolerance.[12]
  • Malabsorption.
  • Flatulence (and belching) are common in female runners. The cause for this has yet to be elucidated.[13]
  • 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, family history of bowel cancer.[14]
  • Clinical examination (if relevant) to look for any serious signs - eg, anaemia, nodes and abdominal, pelvic or rectal masses.

These depend on the clinical picture. Basic tests may be relevant to help rule out other problems (eg, as recommended in the diagnosis of irritable bowel syndrome):[14]

  • FBC.
  • ESR or CRP.
  • Antibody testing for coeliac disease.

Breath tests may be used to assess intestinal flora and small intestinal bacterial overgrowth, usually in the context of research studies.[11]


  • Explanation of normal physiology and reassurance may be sufficient.
  • Investigate/treat dyspepsia and reflux symptoms if relevant.[2]
  • Speech therapy or behavioural therapy may be used.[2, 15]


Note that most of the research and literature on this topic relates 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.[16]
  • Treating exacerbating factors such as constipation.
  • Diet:
    • Soluble fibre such as linseed (up to one tablespoon daily) and oats.[14]
    • Diets low in fermentable carbohydrate can reduce flatulence in IBS.[17]
  • Probiotics:[18]
    • 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 reduce flatulence in patients with IBS.
    • The specific strain of bacteria may be important but, on current evidence, it is difficult to advise which strain(s) to use.
  • Drugs:
    • Antibiotics (eg, metronidazole or rifaximin) can be used to treat small intestinal bacterial overgrowth.[11, 19]One study reported that rifaximin was more effective and better tolerated than metronidazole.[20]
    • Simeticone combined with loperamide may improve gas symptoms in acute diarrhoea.[3]Neither simeticone nor activated charcoal has a beneficial effect in IBS-related gas symptoms.[21]
    • Oral bismuth subsalicylate binds sulfide gases in the gut but is not safe for regular use due to the salicylate content.[3]
  • Supplements:
    • Alpha-galactosidase, an enzyme supplement, has been shown to reduce flatus after eating beans.[22]One study reported that it is particularly effective in children.[23]
  • Odour reduction devices:
    • Garment devices containing activated charcoal have been tested in one trial. This found that briefs containing charcoal were effective, but pads and cushions of the same material were less helpful.[24]

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Original Author:
Dr Naomi Hartree
Current Version:
Dr Laurence Knott
Peer Reviewer:
Prof Cathy Jackson
Document ID:
1570 (v23)
Last Checked:
21 August 2014
Next Review:
20 August 2019

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.