What Causes Bloating, and Why Tests Are Often Normal

Bloating is usually gas. The NHS says "the most common reason for bloating is having a lot of gas in your gut", from some foods and drinks or from swallowing air, with constipation, a food intolerance, coeliac disease and IBS the digestive problems it names next; a swollen-looking stomach can be an abdominal-wall reflex rather than extra gas, so tests are often normal.^{1, 2} Bloating that is regular, that diet changes have not helped, or that comes with weight loss or blood in your poo is a GP appointment in the NHS's words.¹ This page is the parent of the Wellgard pages on whether a particular supplement or medicine causes bloating, each linked below.

Sources checked on 5 November 2026.

Evidence at a glance

• How common: bloating in 19% and visible distension in 9% of the general population in the surveys the 2025 European consensus cites; functional bloating, where it is the main recurring symptom and no disease is found, in 3.5% of people.²
• Why it looks swollen: in two placebo-controlled trials of 42 and 44 patients, retraining the abdominal wall cut visible distension scores by 66% and 56%, against no such effect and 13% on placebo.^{3, 4}
• Food: about one in five adults with functional bloating reacted to 8 g a day of a fermentable fibre in a double-blind crossover challenge (7 of 39 to fructan, 8 of 40 to a galacto-oligosaccharide), in a trial funded by a food company.⁵
• Tests: the consensus says laboratory, imaging and endoscopy tests are unnecessary without alarm signs; of 100,856 UK primary-care patients who consulted for bloating or distension, 0.54% of the women were diagnosed with ovarian cancer within a year.^{2, 15}

What is bloating, and how common is it?

Bloating is a feeling. The European consensus defines it as "a feeling of abdominal fullness and discomfort" and abdominal distension as "an objective visible sign of increased abdominal girth", and says the two may occur together or apart.² The NHS puts it more plainly: "Bloating is where your tummy feels full and uncomfortable", and you may be bloated if your tummy feels full or bigger than usual, you have tummy pain or discomfort, your tummy is rumbling or you're farting more than usual.¹ It is common. The consensus cites surveys putting bloating at 19% and distension at 9% of the general population, a worldwide study at 18%, and 66% to 90% in people with IBS.² Functional bloating and distension, the diagnosis when bloating is the main recurring symptom and no disease is found, affect 3.5% of people worldwide and 4.6% of women, most often between 40 and 60, and women report the symptoms about 2.8 times as often as men.²

What causes bloating?

The consensus counts four ways gas gets into the gut: by swallowing air, by chemical processes that liberate gas, by diffusion from the blood, and by gas-producing bacteria; it leaves by belching, by diffusion back into the blood, by being consumed by other microbes, or by passing wind.² The NHS list of causes is shorter and is the place to start: gas from some food and drinks or from swallowing air, then constipation, a food intolerance, coeliac disease and irritable bowel syndrome, with some people bloated around the time of their period, and, sometimes, bloating that does not go away as a sign of something more serious such as ovarian cancer.¹ The table maps those causes, with the two the consensus adds: a sensitive gut and the abdominal-wall reflex.

Fermentable carbohydrate is the best-tested food cause, and the surprise is how few people react. In a double-blind, placebo-controlled crossover challenge of 41 adults with functional bloating, 8 g a day of fructan for seven days set off bloating in 7 of the 39 who completed it (17.9%), and 8 g a day of a galacto-oligosaccharide in 8 of 40 (20%); the responders had more bloating before the challenge began and a larger abdominal girth after it. The trial was funded entirely by a multinational food company, and five of its authors are the company's employees.⁵ Fructans, not gluten, were also what set off bloating in 59 adults who believed themselves gluten-sensitive, with coeliac disease excluded: on the bloating scale the scores were 11.6 on fructan, 9.3 on gluten and 10.1 on placebo, with no difference between gluten and placebo.⁶ Beans earn their reputation only in the first week. Across three feeding studies of 17, 29 and 80 adults eating half a cup of beans a day for 8 or 12 weeks, fewer than half reported more flatulence from pinto or baked beans in week one and 19% from black-eyed peas, while 3% to 11% reported more flatulence on control diets with no beans at all, and reports fell as the weeks went on.⁷

Lactose intolerance is a cause the NHS names, and the dose decides it: a systematic review of 36 randomised studies found moderate-quality evidence that 12 to 15 g of lactose, about a cup of milk, is well tolerated by most adults, with the caveat that most studies recruited people who malabsorb lactose rather than people with symptoms.⁹ The NHS says to see a GP if the symptoms keep coming back and often happen after eating, or if you have had tummy bloating and discomfort for 3 weeks, and not to cut foods out of your diet without the advice of a GP or a dietitian.¹⁰ Coeliac disease is found with a blood test taken while you are still eating gluten; persistent unexplained bloating with diarrhoea or stomach ache is on the NHS list of reasons to be tested, and the NHS says: "You should also not start a gluten-free diet until the diagnosis is confirmed by a specialist, even if the results of a blood test are positive."¹¹ Excessive wind can also be a side effect of medicines, and the NHS wind page names NSAIDs like ibuprofen, some laxatives, antifungal medicines and statins, with one rule: "Do not stop or change your medicine without speaking to a GP first."¹³

Why does a bloated stomach look swollen?

Because the body's reaction to gas matters as much as the gas itself. Healthy volunteers and people with IBS hold similar volumes of gas, at rest and after a fermentable load such as inulin, and only the people with IBS feel it; the consensus concludes that functional bloating is driven more by a sensitive gut, which it calls visceral hypersensitivity, than by actual distension.² The visible swelling has a mechanism of its own. Normally, when the bowel fills, the diaphragm relaxes and the abdominal wall tightens to hold its shape; in an episode of distension the reverse happens, the diaphragm contracts and descends while the abdominal wall relaxes, so the belly bulges "despite only a slight increase in intestinal gas volume". The consensus calls this abdomino-phrenic dyssynergia and names it, with a sensitive gut, slow transit and an altered gut microbiota, as the mechanisms of functional bloating.²

The reflex can be retrained, which is the clearest evidence that the wall, not the gas, makes the shape. In a 2024 placebo-controlled trial, 42 patients with meal-triggered visible distension, 36 of them women, were randomised to three sessions of biofeedback over four weeks, watching the movement of their own chest and abdominal wall and learning to move the diaphragm, or to a placebo capsule three times a day. In the biofeedback group intercostal muscle activity fell 82%, abdominal-wall activity rose 97%, the increase in girth after a test meal was 108% smaller and distension scores fell 66%; none of these effects was seen on placebo (all P < 0.002).³ An earlier trial at the same Spanish centre enrolled 48 patients with visible distension and a functional bowel disorder, analysed 44, and set electromyography-guided biofeedback against oral simeticone as the placebo over ten days: distension fell 56% (a mean score of 4.6 to 2.0) against 13% (4.7 to 4.1), P < 0.001.⁴ Neither trial states its funding on PubMed. The consensus lists biofeedback-guided retraining of the abdominal and chest muscles among the treatments a specialist may use for discrete episodes of visible distension, on very-low-level evidence from these small trials.²

Why do I bloat after eating?

Because eating is when gas is made, air is swallowed and the reflex is triggered, and no trial we could find has separated the three. The consensus gives a practical rule for telling them apart: bloating that comes with meals, at night or with smelly wind suggests gas made in the bowel, while belching, excessive salivation or a start linked to stress suggests swallowed air.² One small test in healthy volunteers shows how fast it happens. Sixteen volunteers drank a 355-calorie liquid meal that was 55% fat, and fullness, bloating and nausea all rose within ten minutes (p < 0.01) while the stomach's normal electrical rhythm fell; the enzyme capsule the trial was built to test lowered fullness only, not bloating or nausea.⁸ Meal size itself has not been isolated in a trial, so the NHS advice to "eat smaller, more frequent meals instead of large meals" and not to "eat large meals late at night before bed or slouch when eating" rests on the physiology rather than a trial.¹ The fructan and bean trials above are the food evidence; why does fibre make me bloated has the fibre-by-fibre table and the three-week timeline.

When should you see a GP about bloating?

The NHS bloating page, last reviewed 21 January 2026, sets three tiers.¹

• See a GP if: "you feel bloated regularly"; "you've tried changing your diet but keep feeling bloated"; "you have bloating and unintentional weight loss"; "you have bloating and also have blood in your poo".
• Ask for an urgent GP appointment or call 111 if: "you have bloating with vomiting (being sick), diarrhoea or constipation"; "you have bloating with a stomach ache"; "you have a high temperature (fever), or feel hot, cold or shivery"; "you have a swelling or lump in your tummy"; "you cannot pee, poo or fart"; "you have a burning feeling in your chest caused by stomach acid travelling up towards your throat (acid reflux)".
• Call 999 or go to A&E if you have bloating with a swollen stomach and: "you have a stomach ache that is severe and came on very suddenly"; "you're vomiting blood or your vomit looks like ground coffee"; "you have severe difficulty breathing".

The NHS wind page, reviewed 2 April 2026, adds a GP visit for "a stomach ache or bloating that will not go away or comes back", for constipation or diarrhoea that keeps happening, for weight loss without trying and for blood in your poo.¹³

Ovarian cancer has its own rule, on the NHS ovarian cancer page reviewed 17 November 2025: its symptoms include "frequently (roughly 12 or more times a month) having: a swollen tummy or feeling bloated", pain or tenderness in your tummy or the area between your hips, no appetite or feeling full quickly after eating, and an urgent need to pee or needing to pee more often, and the NHS says to see a GP if you have any of them. It also says: "The symptoms of ovarian cancer are very common and can be caused by many different conditions. But it's still important to get them checked by a GP."¹⁴ The size of that "very common" is on record. In UK primary-care records from 2000 to 2017, 100,856 patients consulted a GP with abdominal bloating or distension, 73% of them women; in the year that followed, 0.54% of the women were diagnosed with ovarian cancer (395 cases), 1.33% of the women and 1.65% of the men with any cancer, and about 1% of each with inflammatory bowel disease; the study was funded by the Medical Research Council and Cancer Research UK and its authors declare no competing interests.¹⁵ Bloating was the one symptom named in all 18 international guidance documents on assessing possible ovarian cancer, and an ultrasound scan and the CA125 blood test were the first tests those documents most often advised, which is the route the NHS page describes.^{14, 16} So roughly one woman in 200 (0.54%) who sees a GP about bloating or a swollen tummy is diagnosed with ovarian cancer within the year. The NHS asks everyone with the pattern to go rather than wait because, in its words, "if they're caused by cancer, finding it early can mean it's more treatable".^{14, 15}

Why do tests come back normal?

Because for most bloating there is nothing for a test to find, and the guidelines say so. The 2025 European consensus on functional bloating and abdominal distension, from a panel of 21 specialists voting by Delphi process (an erratum published in January 2026 corrects a product name in one sentence and changes no statement or figure), says the diagnosis is made on the physical examination, the medical history and the search for alarm signs, and that "in the absence of alarming signs or any relevant finding, clinical laboratory, imaging or endoscopic tests are unnecessary".² Its statements go further: endoscopy and imaging "have limited diagnostic value" in functional bloating, though they may be needed to rule out other causes; microbiota stool tests "do not provide useful information for diagnosing bloating or abdominal distension and should not be used"; measuring the volume of gas in the bowel is for research; and younger patients with stable symptoms over six months often need minimal further investigation.²

What a UK GP does test is the short list that excludes other diagnoses. NICE's IBS guideline names a full blood count, an inflammation marker (ESR, plasma viscosity or C-reactive protein) and coeliac antibodies, and says ultrasound, sigmoidoscopy or colonoscopy, a thyroid test and a hydrogen breath test are not necessary to confirm IBS in people who meet its criteria.¹⁷ The consensus adds the conditions a doctor keeps in mind when the picture is not typical: carbohydrate intolerance, pancreatic insufficiency (checked with a stool elastase test), Crohn's disease and coeliac disease, an underactive thyroid and diabetes, and in women the conditions linked to hormone fluctuations.² So "your tests are normal" usually means the serious causes have been excluded and the mechanism is one of the four above, which no blood test measures. The NHS bloating page says "Treatment for bloating is often not needed", and that a GP may refer you to an NHS dietitian if general diet tips have not helped, or to a specialist for tests to find out what may be causing it.¹

Could it be IBS, and where does the low FODMAP diet fit?

IBS is a GP diagnosis made on the pattern of symptoms; NICE asks GPs to consider it after six months of abdominal pain or discomfort, bloating or a change in bowel habit, with the red-flag signs of cancer and inflammatory bowel disease checked first.¹⁷ The criteria, the triggers and the NHS and NICE options are on the Wellgard IBS page. The low FODMAP diet belongs to that route. NICE says exclusion diets such as a low FODMAP diet are for people whose symptoms persist on general lifestyle and dietary advice and should "only be given by a healthcare professional with expertise in dietary management", and the NHS IBS page says a GP may refer you to a dietitian.^{17, 18} The consensus grades a low FODMAP diet as effective for functional bloating on moderate evidence with a weak recommendation, finds insufficient evidence for a gluten-free diet unless you have coeliac disease, and voted against a lactose-limiting diet for everyone with functional bloating, keeping it for people whose own symptoms or a breath test point to lactose, because in most people the symptoms are not related to lactose intolerance.² The trials behind the diet are on which fibre is best for IBS.

What does the NHS say helps while it passes?

The NHS bloating page gives six things to do and five not to do.¹ Do: exercise regularly; chew with your mouth closed to avoid swallowing air; drink plenty of water; eat foods high in soluble fibre, such as oats or linseed, if constipated; eat smaller, more frequent meals instead of large meals; and massage your stomach from right to left to release trapped wind. Do not: drink lots of fizzy drinks, alcohol or caffeine; eat lots of foods known to cause gas, like cabbage, beans or lentils; eat large meals late at night or slouch when eating; eat lots of processed, sugary, spicy or fatty foods; or eat food you are intolerant to. Its wind page adds eating and drinking slowly, not smoking or chewing gum, and drinking peppermint tea.¹³ One caution on the last: the EU herbal monograph on peppermint leaf says people with gastro-oesophageal reflux (heartburn) should avoid peppermint leaf preparations, because heartburn may increase.²²

How much of that has been tested? Little, and the NHS does not claim otherwise. The one randomised trial of a walk after meals was open-label: 94 adults with functional bloating (24 men and 70 women, mean age 44) were randomised to a 10 to 15 minute walk after each meal or to a prokinetic medicine with dimeticone for four weeks; both groups improved on every symptom (p < 0.001), and walking beat the medicine only for post-meal fullness and bloating (p = 0.002). There was no placebo or no-treatment group, so the trial cannot say how much either group would have improved on its own; the authors declare no conflict of interest and name no funder.¹⁹ The consensus finds no pooled-trial evidence that exercise works for functional bloating, only observational hints, and grades physical activity as expert opinion.²

A pharmacist is the NHS's next step: the bloating page says you can ask a pharmacist about laxatives for constipation and "medicines like simeticone".¹ The record on simeticone is thin and mixed. In 185 adults with functional dyspepsia, 105 mg three times a day beat placebo on a global symptom score at two, four and eight weeks, with 46% rating the effect very good against 16% on placebo (funding not stated on PubMed); in 10 healthy volunteers given 30 g of lactulose to make gas, 600 mg of simeticone made no difference to breath hydrogen or symptoms; and the consensus finds "insufficient evidence to recommend simethicone" for functional bloating.^{2, 20, 21} No supplement is named here as something to take for bloating: the trials of each one belong to the page that owns it, and the questions people ask about them are indexed next.

Does collagen, creatine, fibre or a medicine cause bloating? Where each answer is

The NHS list of causes names no supplement, so each "does X cause bloating" question is answered on the page that holds that ingredient's or medicine's own trial record.¹

• Collagen. Not on the NHS list; whether a serving bloats, why constipation and loose stools happen and what the trials recorded is on does collagen cause bloating or constipation.
• Creatine. Not on the NHS list; the serving-size trial, muscle water against gut bloating and how to take it without an upset stomach are on does creatine cause bloating.
• Fibre, inulin and psyllium. The NHS names oats and linseed for bloating with constipation and cabbage, beans and lentils among the foods that cause gas;¹ which fibres ferment, how long the wind lasts and the signs of too much are on why does fibre make me bloated, and the pace of building up on what is fibremaxxing.
• Mounjaro (tirzepatide). Whether it bloats and why a slowed stomach does is on Mounjaro constipation and diarrhoea; heartburn is on why does Mounjaro cause heartburn and burping on sulphur burps on Mounjaro.
• Live cultures. The first-days wind and bloating the trials record, and the reflux question, are on can probiotics cause acid reflux; the counts at high doses on the side effects of too much probiotics.
• Iron tablets. The NHS lists diarrhoea or constipation, stomach pain, heartburn (indigestion) and feeling sick among the common side effects of ferrous fumarate;²³ the trial counts by dose and form are on iron supplement side effects.
• Magnesium. Loose stools are the recorded side effect; the trials and the dose where they began are on magnesium side effects.
• Protein powder. What a serving contains and the gut question are on is vegan protein powder healthy.
• Omeprazole and the other acid-suppressing medicines. The bloating and overgrowth question is answered on can I take probiotics with omeprazole.
• Constipation. The NHS definition, the causes people miss and the foods with trial doses are on the Wellgard constipation guide.
• Other medicines. The NHS wind page's list is in the table above; the medicine's own NHS page and your pharmacist are the next step.¹³

What we don't know

• Whether meal size or eating speed causes bloating on its own: no trial we could find has isolated either, so the NHS advice on smaller, slower meals rests on physiology.^{1, 8}
• Whether a walk after meals helps more than doing nothing: the one randomised trial compared it with a medicine and had no untreated group.¹⁹
• Whether breathing exercises do anything: a six-week trial randomised 85 adults with bloating to written instructions for diaphragmatic breathing or to a breathing device, with no inactive control; bloating improved in both arms with no difference between them, and higher anxiety at the start predicted improvement.²⁴
• Why only about one in five people with functional bloating react to a fermentable-fibre challenge: the trial found trends in the gut bacteria's carbohydrate enzymes but says firm conclusions cannot yet be drawn.⁵
• Whether abdominal-wall biofeedback works outside the one research group that ran both trials, and how it is reached in the UK: neither trial says.^{3, 4}

Frequently asked questions

Why am I so bloated all the time?

Regular bloating is a GP question, not a food puzzle: the NHS says to see a GP if "you feel bloated regularly" or if you have tried changing your diet and keep feeling bloated.¹ The GP's tests exclude coeliac disease, inflammation and anaemia; when they come back normal, the consensus's explanation is one of the four mechanisms above, and functional bloating of that kind affects about 3.5% of people and 4.6% of women.^{2, 17}

Can constipation cause bloating?

Yes. Constipation is on the NHS list of causes of bloating, the NHS constipation page says you "may also have a stomach ache and feel bloated or sick", and being regularly bloated is one of its reasons to see a GP.^{1, 12} The NHS definition, what helps and the order of steps are on the Wellgard constipation guide.

How do you get rid of trapped wind?

In the NHS's words, "massage your stomach from right to left to release trapped wind", exercise regularly, chew with your mouth closed and eat smaller meals; a pharmacist can suggest medicines like simeticone, and the full list is in the section above.¹ The one trial of a walk after meals had no untreated group and the simeticone trials are mixed, so the evidence behind each is thin; the NHS says to see a GP if wind is affecting your life and self-help and pharmacy treatments have not worked.^{13, 19, 20, 21}

Does bloating mean I have a food intolerance?

Sometimes: the NHS names a food intolerance among the causes, but the trials above argue for testing before cutting, since most adults tolerate about a cup of milk's worth of lactose, fructans rather than gluten set off the bloating in people who thought themselves gluten-sensitive, and only about one in five people with functional bloating reacted to a fermentable-fibre challenge.^{1, 5, 6, 9} The NHS says not to cut foods out without a GP's or dietitian's advice, and to have the coeliac blood test while still eating gluten.^{10, 11}

Sources

1. NHS. Bloating. Page last reviewed 21 January 2026. Symptoms, causes, the do and do not lists, the pharmacist line and the three tiers of when to get help. nhs.uk.
2. Melchior C, et al. European consensus on functional bloating and abdominal distension: ESNM/UEG recommendations for clinical management. United European Gastroenterology Journal, 2025. Consensus statement by literature review and Delphi vote, 21 experts; funded by a United European Gastroenterology activity grant; three authors declare consultancy, speaker fees or research grants from pharmaceutical and nutrition companies and the rest declare none. Erratum of January 2026 (PubMed 41607061) corrects the name of one probiotic formulation in one sentence. PubMed 40844856; full text PMC12606050.
3. Barba E, et al. Thoracoabdominal wall motion-guided biofeedback treatment of abdominal distention: a randomized placebo-controlled trial. Gastroenterology, 2024. Randomised placebo-controlled trial, 42 patients with meal-triggered visible distension, 4 weeks; funding not stated on PubMed. PubMed 38467383.
4. Barba E, Accarino A, Azpiroz F. Correction of abdominal distention by biofeedback-guided control of abdominothoracic muscular activity in a randomized, placebo-controlled trial. Clinical Gastroenterology and Hepatology, 2017. Randomised placebo-controlled trial, 48 patients enrolled and 44 analysed, 10 days; funding not stated on PubMed. PubMed 28705783.
5. Farsi DN, et al. Gut microbiome composition and function, diet, and clinical factors in relation to fermentable carbohydrate-induced bloating: a double-blind, randomized, crossover trial. American Journal of Gastroenterology, 2026. Double-blind placebo-controlled crossover challenge, 41 adults with functional bloating, 7 days per challenge; funded entirely by a multinational food company, five authors its employees (full text). PubMed 41841608; full text PMC13722433.
6. Skodje GI, et al. Fructan, rather than gluten, induces symptoms in patients with self-reported non-celiac gluten sensitivity. Gastroenterology, 2018. Double-blind placebo-controlled crossover, 59 adults, 7 days per challenge; research support from a source other than the US government listed on PubMed. PubMed 29102613.
7. Winham DM, Hutchins AM. Perceptions of flatulence from bean consumption among adults in 3 feeding studies. Nutrition Journal, 2011. Two randomised crossover studies and one parallel trial, 17, 29 and 80 adults, 8 or 12 weeks; funding not stated on PubMed, authors declare no competing interests (full text PMC3228670). PubMed 22104320.
8. Levine ME, Koch SY, Koch KL. Lipase supplementation before a high-fat meal reduces perceptions of fullness in healthy subjects. Gut and Liver, 2015. Double-blind placebo-controlled crossover test meal, 16 healthy volunteers, 60 minutes; research support from a source other than the US government listed on PubMed. PubMed 25287168.
9. Shaukat A, et al. Systematic review: effective management strategies for lactose intolerance. Annals of Internal Medicine, 2010. Systematic review, 36 randomised studies in people with lactose intolerance or malabsorption; US National Institutes of Health funding. PubMed 20404262.
10. NHS. Lactose intolerance. Page last reviewed 8 July 2026. nhs.uk.
11. NHS. Coeliac disease: diagnosis. Page last reviewed 31 March 2023 (review overdue). nhs.uk.
12. NHS. Constipation. Page last reviewed 26 October 2023 (review overdue). nhs.uk.
13. NHS. Farting (flatulence). Page last reviewed 2 April 2026. The gas-forming foods, the medicines that cause wind, and when to see a GP. nhs.uk.
14. NHS. Ovarian cancer: symptoms. Page last reviewed 17 November 2025. nhs.uk.
15. Herbert A, et al. Predictive values for different cancers and inflammatory bowel disease of 6 common abdominal symptoms among more than 1.9 million primary care patients in the UK: a cohort study. PLoS Medicine, 2021. Cohort study of UK primary-care records (THIN, 2000 to 2017); bloating or distension cohort 100,856 patients, 73% women, one year of follow-up; Medical Research Council and Cancer Research UK; no competing interests. PubMed 34339405; full text PMC8367005.
16. Funston G, et al. Variation in the initial assessment and investigation for ovarian cancer in symptomatic women: a systematic review of international guidelines. BMC Cancer, 2019. Systematic review of 18 guidance documents from 11 countries; UK Department of Health and Cancer Research UK; one author led the NICE suspected-cancer guideline and took no part in its appraisal. PubMed 31676000.
17. NICE. Irritable bowel syndrome in adults: diagnosis and management (CG61), recommendations 1.1.1.1 to 1.1.2.2, 1.2.1.4, 1.2.1.5 and 1.2.1.8. Clinical guideline, published 23 February 2008, last updated 4 April 2017. nice.org.uk.
18. NHS. Diet, lifestyle and medicines for IBS. Page last reviewed 17 March 2025. nhs.uk.
19. Hosseini-Asl MK, Taherifard E, Mousavi MR. The effect of a short-term physical activity after meals on gastrointestinal symptoms in individuals with functional abdominal bloating: a randomized clinical trial. Gastroenterology and Hepatology from Bed to Bench, 2021. Randomised open-label trial, 94 adults with functional bloating, 4 weeks, no placebo or no-treatment group; authors declare no conflict of interest, funder not stated (full text). PubMed 33868611; full text PMC8035544.
20. Holtmann G, et al. A randomized placebo-controlled trial of simethicone and cisapride for the treatment of patients with functional dyspepsia. Alimentary Pharmacology and Therapeutics, 2002. Randomised double-blind double-dummy trial, 185 adults with functional dyspepsia, 8 weeks; funding not stated on PubMed (research support from a source other than the US government listed). PubMed 12197843.
21. Friis H, et al. Effect of simethicone on lactulose-induced H2 production and gastrointestinal symptoms. Digestion, 1991. Randomised double-blind crossover challenge, 10 healthy volunteers; funding not stated on PubMed (research support from a source other than the US government listed). PubMed 1797602.
22. European Medicines Agency, Committee on Herbal Medicinal Products. European Union herbal monograph on Mentha x piperita L., folium (peppermint leaf), revision 1, EMA/HMPC/572705/2014. Regulator monograph; sections 4.4 and 4.8. ema.europa.eu.
23. NHS. Ferrous fumarate. Page last reviewed 13 March 2026. nhs.uk.
24. Chakraborty S. Comparing biofeedback device vs diaphragmatic breathing for bloating relief: a randomized controlled trial. Open Medicine, 2025. Randomised trial of two breathing interventions with no inactive control, 85 adults with bloating, 6 weeks; the device was supplied by its maker, which the paper says had no role; no conflict of interest declared (full text). PubMed 41323646; full text PMC12658723.

Spotted something out of date? Email support@wellgard.co.uk with the page address and the sentence.

This article is general information, not medical advice. Bloating that is regular, that has not settled with diet changes, or that comes with weight loss, blood in your poo, vomiting, a stomach ache or a lump is a GP matter in the NHS's words, and a prescribed medicine is never stopped without speaking to a GP first.