Statistics — irritable bowel syndrome¶
Quick-reference tables. Every figure carries its source, year, population and method. Conflicting estimates are shown side by side and never averaged; a closing section names the conflicts explicitly. All PMIDs were resolved live from PubMed E-utilities and all ClinicalTrials.gov counts retrieved from the v2 API on 2026-09-02.
Reading rule for this whole file: IBS is criteria-defined, so almost every number below is conditional on which Rome criteria (or Manning) defined the population. The criteria column is not optional context — it is part of the measurement.
1. Prevalence¶
| Estimate | 95% CI | Criteria | Population / method | Year | Source |
|---|---|---|---|---|---|
| 9.2% | 7.6–10.8 | Rome III | 53 population-based studies, 38 countries, 395,385 participants; uniform methodology required | 2020 | Oka 2020, PMID 32702295 |
| 3.8% | 3.1–4.5 | Rome IV | 6 population-based studies, 34 countries, 82,476 participants | 2020 | Oka 2020, PMID 32702295 |
| 10.1% | — | Rome III | Rome Foundation Global Study, internet arm, 73,076 adults, 33 countries | 2021 | Sperber 2021, PMID 32294476 |
| 4.1% | — | Rome IV | same survey, same respondents | 2021 | Sperber 2021, PMID 32294476 |
| 3.5% | — | Rome III | same study, household-interview arm | 2021 | Sperber 2021, PMID 32294476 |
| 1.5% | — | Rome IV | same study, household-interview arm | 2021 | Sperber 2021, PMID 32294476 |
| 9.0% | — | Rome III | 5,931 adults, USA/Canada/UK, census-adjusted online survey | 2020 | Palsson 2020, PMID 31917991 |
| 4.4–4.8% (by country) | — | Rome IV | same survey | 2020 | Palsson 2020, PMID 31917991 |
| 8.5% | — | Rome V | 28,771 adults, 15 countries, population-based internet survey | 2026 | Sperber 2026, PMID 42613194 |
| 6.1% | — | Rome IV | 88,607 US adults, online national health survey, May–June 2020 | 2023 | Almario 2023, PMID 37595647 |
| 11.2% | 9.8–12.8 | Manning / Rome I–III mixed | 80 populations, 260,960 subjects; country range 1.1–45.0% | 2012 | Lovell 2012, PMID 22426087 |
| 14.1% | — | Rome III or IV pooled | 96 studies, 52 countries | 2025 | Arif 2025, PMID 40359286 |
| 13.21% | 10.70–15.94 | Rome III | 26 studies within a 43-study pool, 188,885 participants | 2025 | Ballena-Caicedo 2025, PMID 41488823 |
| 17.14% | 12.00–22.99 | Rome IV | 17 studies within the same pool — direction opposite to Oka 2020 | 2025 | Ballena-Caicedo 2025, PMID 41488823 |
| 11.19% / 13.28% | — | Rome III / Rome IV | same pool restricted to probabilistic sampling | 2025 | Ballena-Caicedo 2025, PMID 41488823 |
| 12.6% | 11.6–13.7 | Rome III | 3,910 urban adults, Japan/China/South Korea, one instrument; significant between-country differences | 2023 | Takeoka 2023, PMID 37019867 |
| 15.4% | — | Rome III | 5,986 Danes aged 18–50, web panel | 2017 | Krogsgaard 2017, PMID 27865035 |
| 28.4% | — | Rome IV | 858 US veterans, questionnaire survey | 2023 | Shin 2023, PMID 35964894 |
| Women 13.8% / men 4.2% | — | self-report | 546,246 US veterans, Million Veteran Program; highest in White women (14.7%) | 2026 | Gasperi 2026, PMID 41489281 |
Any disorder of gut–brain interaction (context)¶
| Estimate | Criteria | Population | Year | Source |
|---|---|---|---|---|
| 40.3% (95% CI 39.9–40.7) internet arm; 20.7% (20.2–21.3) household arm | Rome IV | 73,076 adults, 33 countries | 2021 | Sperber 2021, PMID 32294476 |
| 40.5% | Rome IV | Rome Foundation Global Epidemiology Study | 2026 (comparison) | Sperber 2026, PMID 42613194 |
| 40.9% | Rome V | 28,771 adults, 15 countries | 2026 | Sperber 2026, PMID 42613194 |
| 28.6–31.7% for any Rome IV functional bowel disorder | Rome IV | 5,931 adults, USA/Canada/UK | 2020 | Palsson 2020, PMID 31917991 |
2. Sex, age and demography¶
| Measure | Value | Criteria / population | Source |
|---|---|---|---|
| Female : male odds | OR 1.46 (1.33–1.59); prevalence 12.0% vs 8.6% | Rome III/IV pooled, 92 populations | Oka 2020, PMID 32702295 |
| Female : male odds | OR 1.67 (1.53–1.82) | Manning/Rome I–III, 80 populations | Lovell 2012, PMID 22426087 |
| Female : male odds | OR 1.49 | Rome III/IV, 96 studies | Arif 2025, PMID 40359286 |
| Age >50 vs <50 | OR 0.75 (0.62–0.92) | Manning/Rome I–III | Lovell 2012, PMID 22426087 |
| Stress | OR 2.47 | Rome III/IV, 96 studies | Arif 2025, PMID 40359286 |
| Anxiety | OR 2.93 | same | Arif 2025, PMID 40359286 |
| Depression | OR 2.24 | same | Arif 2025, PMID 40359286 |
| Smoking, alcohol, education | no significant association | same | Arif 2025, PMID 40359286 |
| Race/ethnicity | racial and ethnic minorities had lower odds than non-Hispanic Whites | Rome IV, 88,607 US adults | Almario 2023, PMID 37595647 |
3. Subtype distribution¶
| Source | Criteria | IBS-C | IBS-D | IBS-M | IBS-U |
|---|---|---|---|---|---|
| Oka 2020, PMID 32702295 | Rome III | — | — | 33.8% (modal) | — |
| Oka 2020, PMID 32702295 | Rome IV | — | 31.5% (modal) | — | — |
| Almario 2023, PMID 37595647 | Rome IV, US, n=5,414 | 33.6% | 28.1% | 33.9% | 4.4% |
| Arif 2025, PMID 40359286 | Rome III+IV pooled | 26.1% | 26.5% | 31.4% | 8.3% |
| Arif 2025, PMID 40359286 | by criteria | 34.2% under Rome IV | 26.2% under Rome III | — | — |
| Shin 2023, PMID 35964894 | Rome IV, US veterans, n=244 | 16.8% | 47.5% | 33.6% | — |
4. Incidence, natural history and remission¶
| Measure | Value | Population / method | Source |
|---|---|---|---|
| Community incidence | ~67 per 1,000 person-years | Review of population studies | Yadav 2021, PMID 34927758 |
| Reported symptom resolution | 17–55% across population studies | Review | Yadav 2021, PMID 34927758 |
| Subtype retention through a clinical trial | only 1 in 4 kept baseline subtype | Trial cohort, reviewed | Yadav 2021, PMID 34927758 |
| 3-year incidence | 10.3%; three-fold higher in those with non-specific GI symptoms at baseline | 5,986 Danes 18–50, Rome III | Krogsgaard 2017, PMID 27865035 |
| Persistence | 69% of those meeting criteria in 2010 and 2011 still met them in 2013 | same cohort | Krogsgaard 2017, PMID 27865035 |
| Rome IV criteria retention at 12 months | 73.6% (259/352) | UK registry, Rome IV at baseline | Khasawneh 2026, PMID 41447016 |
| Classification stability at 12 months (Cohen's κ) | stool form 0.60; psychological burden 0.54; most troublesome symptom 0.47; 7-cluster LCA 0.37 | same cohort | Khasawneh 2026, PMID 41447016 |
| IBS-D subtype stability | 83% stable | same cohort | Khasawneh 2026, PMID 41447016 |
| Rome II vs Rome III subtype agreement | 46% (κ 0.19) | 249 IBS patients | Ersryd 2007, PMID 17767480 |
5. Post-infectious IBS¶
| Measure | Value | Source |
|---|---|---|
| Prevalence after acute gastroenteritis | 14.5% (47 studies, 28,170 subjects) | Porcari 2024, PMID 39013599 |
| Odds vs unexposed | OR 4.3 | Porcari 2024, PMID 39013599 |
| Prevalence at 12 months | 10.1% (7.2–14.1) | Klem 2017, PMID 28069350 |
| Prevalence beyond 12 months | 14.5% (7.7–25.5) | Klem 2017, PMID 28069350 |
| Relative risk ≤12 months | RR 4.2 (3.1–5.7) | Klem 2017, PMID 28069350 |
| Relative risk >12 months | RR 2.3 (1.8–3.0) | Klem 2017, PMID 28069350 |
| Pooled odds at study end | OR 5.86 (3.60–9.54) | Thabane 2007, PMID 17661757 |
| Persistence >5 years | 39.8% still had IBS | Porcari 2024, PMID 39013599 |
| Bacterial gastroenteritis, any pathogen | OR 5.8 (4.0–8.3); any pathogen OR 4.9 (3.9–6.1) | Svendsen 2019, PMID 31112663 |
| Campylobacter | 20.7% (Porcari) / 12% (10–15%) (Svendsen) | PMID 39013599 / 31112663 |
| Salmonella | 12% (9–15%); OR 5.5 (2.3–12.8) | Svendsen 2019, PMID 31112663 |
| Shigella | 11% (8–15%); OR 13.8 (4.2–45.4) | Svendsen 2019, PMID 31112663 |
| Clostridioides difficile | 14% (4–29%) | Svendsen 2019, PMID 31112663 |
| E. coli | 12% (5–20%) | Svendsen 2019, PMID 31112663 |
| Parasites/protozoa | 30.1% (2 studies) / 41.9% | PMID 39013599 / 28069350 |
| Viruses | 10.7% | Porcari 2024, PMID 39013599 |
| Norovirus (single outbreak) | 13%; OR 11.40 (3.44–37.82) | Zanini 2012, PMID 22525306 |
| Giardia, 6 years after outbreak | Rome III IBS 39.4%; adjusted RR 3.4 (2.9–3.9) | Hanevik 2014, PMID 25115874 |
| Travellers' diarrhoea | 5.4% exposed vs 1.4% unexposed; pooled RR 3.35 (2.22–5.05) | Schwille-Kiuntke 2015, PMID 25871571 |
| SARS-CoV-2 and Proteobacteria | OR 5.4 each (highest odds) | Porcari 2024, PMID 39013599 |
| Walkerton at 2–3 years | 28.3% among 742 exposed | Marshall 2010, PMID 20427395 |
| Walkerton at 8 years | 15.4%; OR 3.12 (1.99–5.04) vs controls | Marshall 2010, PMID 20427395 |
| Walkerton, children | 10.5% vs 2.5%; OR 4.6 (1.6–13.3) | Thabane 2010, PMID 20179687 |
| Walkerton risk score | AUC 0.70; PI-IBS 10%/35%/60% (derivation), 17%/36%/62% (validation) across risk strata | Thabane 2009, PMID 19568228 |
6. Diagnostic performance¶
| Criteria | Sens | Spec | LR+ | LR− | Population | Source |
|---|---|---|---|---|---|---|
| Manning ≥3 vs organic GI disease | 58% | 74% | — | — | 361 Mayo outpatients | Talley 1990, PMID 2318433 |
| Manning ≥3 vs all non-IBS GI disease | 42% | 85% | — | — | same | Talley 1990, PMID 2318433 |
| Kruis score | 64% | 99% | — | — | 479 outpatients | Kruis 1984, PMID 6724251 |
| Kruis score (alternative operating point) | 83% | 97% | — | — | same | Kruis 1984, PMID 6724251 |
| Rome III (pooled) | — | — | 3.35 (2.97–3.79) | 0.39 (0.34–0.46) | 22 studies, 7,106 patients | Sood 2015, PMID 26076071 |
| Rome III | 87.5% (84.4–90.3) | 75.0% (66.3–82.4) | 3.50 (2.61–4.84) | 0.17 (0.13–0.21) | Leeds, n=726 | Staller 2026, PMID 42392123 |
| Rome IV | 78.9% (75.4–82.1) | 81.0% (73.4–87.2) | 4.16 (2.98–5.95) | 0.26 (0.22–0.31) | Leeds, n=726 | Staller 2026, PMID 42392123 |
| Rome IV | 82.1% | 85.1% | 5.51 (2.95–11.3) | 0.21 (0.14–0.31) | Leeds, n=170 | Goodoory 2025, PMID 39466700 |
| Rome IV, pain frequency relaxed to 3 days/month | 90.2% | 85.1% | 6.06 (3.25–12.2) | 0.11 (0.07–0.19) | Leeds, n=170 | Goodoory 2025, PMID 39466700 |
| Rome V | 66.1% (62.1–69.9) | 80.1% (72.4–86.5) | 3.33 (2.40–4.74) | 0.42 (0.37–0.49) | Leeds, n=726 | Staller 2026, PMID 42392123 |
| Agreement Rome V vs Rome III/IV | κ 0.36–0.55 | — | — | — | same | Staller 2026, PMID 42392123 |
| Faecal calprotectin, IBD vs IBS | 85.8% (78.3–91) | 91.7% (84.5–95.7) | at 1% IBD prevalence: PPV 9%, NPV 99.8% | — | 17 studies, 1,956 patients | Dajti 2023, PMID 37823411 |
| Bristol Stool Form Scale vs stool water content | r = 0.36 (p<0.0001) | — | — | — | IBS crossover trial | Nordin 2022, PMID 36087104 |
| Patient vs physician BSFS agreement | κ = −0.01 (7-point), 0.04 (3-category); concordant 18/64 (28%) | — | — | — | post-hoc of an RCT | Engel 2026, PMID 42289094 |
7. Test yield and differential diagnosis¶
| Condition | Prevalence in symptom-defined IBS | Comparator | Source |
|---|---|---|---|
| Coeliac disease, seropositive | 6% (5–8) | — | Shiha 2025, PMID 40493044 |
| Coeliac disease, biopsy-proven | 2% (2–3); OR 4.42 (2.82–6.92) for positive serology vs controls | 29 studies, 7,209 patients | Shiha 2025, PMID 40493044 |
| Coeliac disease, biopsy-proven (earlier pool) | 4.1% (1.9–7.0); OR 4.34 (1.78–10.6) | 14 studies, 4,204 individuals | Ford 2009, PMID 19364994 |
| Coeliac disease | no increase in North American studies | 36 studies, 15,256 individuals | Irvine 2017, PMID 27753436 |
| IBD, CRC, infectious diarrhoea | pre-test probability <1% each | — | Cash 2002, PMID 12425553 |
| Bile acid malabsorption, SeHCAT <10% | 28.1% (22.6–34.0), range 16.9–35.3% | 6 studies, 908 IBS-D patients | Slattery 2015, PMID 25913530 |
| SeHCAT <5% / <10% / <15% | 10% (7–13) / 32% (29–35) / 26% (23–30) | 18 studies, 1,223 patients | Wedlake 2009, PMID 19570102 |
| Diagnostic yield: SeHCAT <10% | 0.308 (0.247–0.377) | 24 studies | Valentin 2016, PMID 26347530 |
| Diagnostic yield: serum C4 | 0.171 (0.134–0.217) | 6 studies | Valentin 2016, PMID 26347530 |
| Diagnostic yield: serum FGF19 | 0.248 (0.147–0.385) | 3 studies | Valentin 2016, PMID 26347530 |
| Diagnostic yield: 48-h faecal bile acids | 0.255 (0.071–0.606) | 2 studies | Valentin 2016, PMID 26347530 |
| Exocrine pancreatic insufficiency (faecal elastase <100 µg/g) | 6.1% (3.7–9.3) Rome II IBS-D; 5% (2.2–10.4) Rome IV IBS-D | 314 and 140 patients | Leeds 2010, PMID 19835990; Olmos 2022, PMID 35704255 |
| Colonoscopy: CRC / IBD / microscopic colitis | 0.78% / 4.48% / 2.35% | 12 studies, 28,630 IBS patients | Wu 2023, PMID 36168183 |
| CRC without alarm symptoms or age <40 | <0.1% | same | Wu 2023, PMID 36168183 |
| CRC with vs without alarm symptoms | 2.47% vs 0.11% (RD 2.57%, 0.37–4.78) | same | Wu 2023, PMID 36168183 |
| IBD with vs without alarm symptoms | 8.86% vs 4.25% (RD 10.75%, 4.81–16.68) | same | Wu 2023, PMID 36168183 |
| Organic disease at colonoscopy, Rome IV functional bowel disorders | 12% overall; ~6% IBS-C/functional constipation, ~9% IBS-M, ~17% IBS-D/functional diarrhoea (p=0.005) | 646 patients, 98% with alarm features | Asghar 2022, PMID 32882424 |
| Microscopic colitis, diarrhoeal vs constipation phenotypes | 5.7% vs 0% (p<0.001) | same | Asghar 2022, PMID 32882424 |
| Colonoscopy yield without alarm features | 0 of 11 | same | Asghar 2022, PMID 32882424 |
| Registry: IBD / polyps / CRC / coeliac in IBS vs matched controls | 1.6% vs 5.9% (aOR 0.21); 4.1% vs 13.0% (aOR 0.28); 0.8% vs 6.3% (aOR 0.17); 1.9% vs 3.4% (aOR 0.54) | 21,944 Swedish IBS patients | Staller 2021, PMID 34420846 |
| Registry: microscopic colitis in IBS vs controls | 2.9% vs 1.7% (aOR 1.77, 1.61–1.95) | same | Staller 2021, PMID 34420846 |
| Alarm features for CRC: sensitivity | rectal bleeding 49%; weight loss 12.4% | 31 studies, 45,100 patients | Frazzoni 2023, PMID 36241197 |
| Alarm features for CRC: specificity | rectal bleeding 69.8%; weight loss 91.9% | same | Frazzoni 2023, PMID 36241197 |
| Number needed to scope | rectal bleeding 5.3; anaemia 6.7 | same | Frazzoni 2023, PMID 36241197 |
| SIBO by breath test, IBS vs controls | 35.5% (33.6–37.4) vs 29.7% (27.6–31.8); OR 3.7 (2.3–6.0) | 25 studies, 3,192 IBS / 3,320 controls | Shah 2020, PMID 31913194 |
| SIBO by lactulose / glucose breath test / jejunal culture | 54% (32–76) / 31% (14–50) / 4% (2–9) | 12 studies, 1,921 IBS patients | Ford 2009, PMID 19602448 |
8. Treatment effect sizes¶
Diet¶
| Intervention | Outcome | Effect | Source |
|---|---|---|---|
| Low FODMAP + traditional advice (LFTD) | ≥50-point IBS-SSS reduction at 4 weeks | 76% (73/96) | Nybacka 2024, PMID 38643782 |
| Low-carbohydrate diet | same | 71% (69/97) | Nybacka 2024, PMID 38643782 |
| Optimised medical treatment | same | 58% (59/101); p=0.023 across groups | Nybacka 2024, PMID 38643782 |
| Smartphone FODMAP-lowering app vs otilonium bromide, primary care | ≥50-point IBS-SSS reduction at 8 weeks | 71% (155/218) vs 61% (133/217), p=0.03; Rome IV+ 77% vs 62%, p=0.004 | Carbone 2022, PMID 35483886 |
| Starch- and sucrose-reduced diet | RR global symptoms not improving vs habitual | 0.41 (0.26–0.67), 2 trials | Cuffe 2025, PMID 40258374 |
| Low FODMAP | same | 0.51 (0.37–0.70), 24 trials | Cuffe 2025, PMID 40258374 |
| BDA/NICE dietary advice | same | 0.62 (0.43–0.90), 8 trials | Cuffe 2025, PMID 40258374 |
| Low FODMAP | RR bloating not improving | 0.55 (0.37–0.80) — only diet superior to habitual | Cuffe 2025, PMID 40258374 |
| Low FODMAP vs traditional dietary advice | ≥50-point IBS-SSS responders | 50% (19/38) vs 46% (17/37), p=0.72 | Böhn 2015, PMID 26255043 |
| Low FODMAP vs typical Australian diet (provided food) | overall GI symptom VAS | 22.8 mm (16.7–28.8) vs 44.9 mm (36.6–53.1), p<0.001 | Halmos 2014, PMID 24076059 |
| Blinded FODMAP reintroduction | trigger rate by powder | fructans 56%, mannitol 54%, GOS 35%, lactose 28%, fructose 27%, sorbitol 23%, glucose control 26%; mean 2.5 ± 2 triggers/patient | Van den Houte 2024, PMID 38401741 |
| Personalised diet vs low FODMAP, 12-month follow-up | ≥50-point IBS-SSS responders | 62.5% vs 34.5%; risk difference 28.0 percentage points (95% CI 4.2–47.7) | Tunali 2026, PMID 42623122 |
| Fibre supplementation | clinical response | 52% vs 44%; RR 1.21 (1.03–1.41), p=0.02, I²=38%, 16 RCTs, n=1,293 | Staudacher 2026, PMID 42600900 |
| Psyllium specifically | clinical response | RR 1.53 (1.06–2.19) | Staudacher 2026, PMID 42600900 |
| Fibre, integrative GI symptom scores | SMD | −0.25 (−0.67 to 0.17), p=0.25 — not significant | Staudacher 2026, PMID 42600900 |
Drugs¶
| Drug | Endpoint | Drug vs placebo | NNT | NNH (AE discontinuation) | Source |
|---|---|---|---|---|---|
| Linaclotide 290 µg od | FDA composite, 26-week trial | 33.7% vs 13.9% | 5.1 (3.9–7.1) | 35 | Chey 2012, PMID 22986437; Busam 2026, PMID 40471839 |
| Tenapanor 50 mg bd | 6/12-week combined responder | 36.5% vs 23.7% (p<0.001) | — | 16 | Chey 2021, PMID 33337659; Busam 2026, PMID 40471839 |
| Plecanatide 3 / 6 mg | overall responders, two phase 3 trials | 30.2% / 29.5% vs 17.8%; 21.5% / 24.0% vs 14.2% | — | 59 | Brenner 2018, PMID 29545635; Busam 2026, PMID 40471839 |
| Lubiprostone 8 µg bd | overall responders (7-point global relief) | 17.9% vs 10.1% (p=0.001) | — | 53 (p=0.59) | Drossman 2009, PMID 19006537; Busam 2026, PMID 40471839 |
| Tegaserod | — | — | — | 58 (p=0.03) | Busam 2026, PMID 40471839 |
| PEG 3350 + electrolytes | SBMs/week at week 4 | 4.40±2.58 vs 3.11±1.94 (95% CI of difference 1.17–1.95); no pain benefit vs placebo | — | — | Chapman 2013, PMID 23835436 |
| Eluxadoline 75 / 100 mg | composite, weeks 1–12 | IBS-3001 23.9% / 25.1% vs 17.1%; IBS-3002 28.9% / 29.6% vs 16.2% | — | 32 | Lembo 2016, PMID 26789872; Busam 2026, PMID 40471839 |
| Eluxadoline 100 mg (post-loperamide) | composite, 12 weeks | 22.7% vs 10.3% (p=0.002) | ~8 | 32 | Brenner 2019, PMID 31356229 |
| Ramosetron 2.5 µg | global improvement, 12 weeks, 576 women | 50.7% (44.8–56.6) vs 32.0% (26.7–37.8); RR 1.58 (1.29–1.94) | 6 (4–10) | negative, non-significant | Fukudo 2016, PMID 26551550; Busam 2026, PMID 40471839 |
| Ramosetron (meta-analysis) | overall symptom relief | RR 1.70 (1.48–1.95); 4 RCTs, 1,623 patients | — | — | Qi 2018, PMID 29310568 |
| Ondansetron (meta-analysis) | FDA composite | RR of not responding 0.86 (0.75–0.98) | 9 | — | Gunn 2023, PMID 36866724 |
| Ondansetron | stool response | RR 0.65 (0.52–0.82) | 5 | — | Gunn 2023, PMID 36866724 |
| Ondansetron | abdominal pain | RR 0.95 (0.74–1.20) — no benefit | — | — | Gunn 2023, PMID 36866724 |
| Alosetron | — | ranked first for global symptoms (SUCRA 0.82) among 5-HT3 antagonists | — | 14 | Rokkas 2021, PMID 34276193; Busam 2026, PMID 40471839 |
| Rifaximin 550 mg tds × 2 weeks | adequate relief of global symptoms | 40.7% vs 31.7% (p<0.001 combined) | ~11 | negative, non-significant | Pimentel 2011, PMID 21208106; Busam 2026, PMID 40471839 |
| Rifaximin, retreatment | responder | 38.1% vs 31.5% (p=0.03); stool consistency 51.8% vs 50.0% (p=0.42) | — | — | Lembo 2016, PMID 27528177 |
| Rifaximin (pooled, 5 trials) | RR symptoms persisting | 0.84 (0.79–0.90) | — | — | Ford 2018, PMID 30294792 |
| Peppermint oil | RR global symptoms not improving | 0.65 (0.43–0.98) | 4 (2.5–71) | AE RR 1.57 (1.04–2.37) | Ingrosso 2022, PMID 35942669 |
| Peppermint oil | RR abdominal pain not improving | 0.76 (0.62–0.93) | 7 (4–24) | — | Ingrosso 2022, PMID 35942669 |
| Peppermint oil (small-intestinal release) | FDA abdominal-pain response, 8 weeks | 46.8% vs 34.4% placebo, p=0.170 (endpoint not met) | — | — | Weerts 2020, PMID 31470006 |
| Antispasmodics (pooled) | RR symptoms persisting | 0.68 (0.57–0.81), 22 trials, 1,778 patients | — | — | Ford 2008, PMID 19008265 |
| Otilonium | same | 0.55 (0.31–0.97) | — | — | Ford 2008, PMID 19008265 |
| Hyoscine | same | 0.63 (0.51–0.78) | — | — | Ford 2008, PMID 19008265 |
| Mebeverine | RR clinical improvement | 1.13 (0.59–2.16), p=0.71 — not significant | — | — | Darvish-Damavandi 2010, PMID 20128021 |
| Mebeverine (adolescents) | treatment success | 23.4% vs 22.0%; OR 1.08 (0.59–1.99), p=0.81 | — | — | Rexwinkel 2025, PMID 40074185 |
| Drug label "mebeverine" vs blinded label | treatment success | 31.6% vs 14.1%; OR 2.84 (1.52–5.34), p=0.001 | — | — | Rexwinkel 2025, PMID 40074185 |
| Tricyclics | RR global symptoms not improving | 0.70 (0.62–0.80), 11 trials, 1,144 patients, moderate certainty | — | 24 | Khasawneh 2025, PMID 40258375; Busam 2026, PMID 40471839 |
| Tricyclics | RR abdominal pain not improving | 0.69 (0.54–0.87), 7 trials, 708 patients | — | — | Khasawneh 2025, PMID 40258375 |
| SSRIs | RR abdominal pain not improving | 0.74 (0.56–0.99), 7 trials, 324 patients | — | — | Khasawneh 2025, PMID 40258375 |
| SNRIs | RR abdominal pain not improving | 0.22 (0.08–0.59) — 2 trials, 94 patients only | — | — | Khasawneh 2025, PMID 40258375 |
| All gut–brain neuromodulators | RR global symptoms not improving | 0.77 (0.69–0.87), 22 trials, 2,222 patients | — | — | Khasawneh 2025, PMID 40258375 |
| Amitriptyline 10–30 mg (ATLANTIS) | IBS-SSS at 6 months | −27.0 (−46.9 to −7.10), p=0.0079 (prespecified MCID 35) | — | AE withdrawals 12.9% vs 8.7% | Ford 2023, PMID 37858323 |
| Amitriptyline (ATLANTIS) | subjective global assessment of relief | OR 1.78 (1.19–2.66), p=0.005 | — | — | Ford 2023, PMID 37858323 |
| Ethosuximide (T-type Ca channel blocker) | responder rate | 26.6% vs 23.3%; RR 1.14 (0.61–2.11) — negative | — | discontinuation 46.9% vs 21.7%, p=0.003 | Kerckhove 2026, PMID 41505133 |
Psychological and behavioural therapy¶
| Therapy | RR global symptoms not improving vs waiting list | P-score | Trials / patients | Source |
|---|---|---|---|---|
| Minimal-contact CBT | 0.55 (0.39–0.76) | 0.78 | 2 / 511 | Thakur 2025, PMID 41077057 |
| Telephone disease self-management | 0.57 (0.41–0.80) | 0.75 | 2 / 746 | Thakur 2025, PMID 41077057 |
| Dynamic psychotherapy | 0.59 (0.43–0.80) | 0.72 | 3 / 303 | Thakur 2025, PMID 41077057 |
| CBT | 0.65 (0.53–0.80) | 0.64 | 9 / 1,150 | Thakur 2025, PMID 41077057 |
| Disease self-management | 0.68 (0.50–0.92) | 0.58 | 3 / 375 | Thakur 2025, PMID 41077057 |
| Internet-based minimal-contact CBT | 0.77 (0.61–0.96) | 0.43 | 5 / 705 | Thakur 2025, PMID 41077057 |
| Gut-directed hypnotherapy | 0.79 (0.66–0.95) | 0.39 | 12 / 1,507 | Thakur 2025, PMID 41077057 |
| Telephone CBT (ACTIB) | IBS-SSS at 12 months vs usual care | −61.6 (33.8–89.5), p<0.001 | 558 randomised | Everitt 2019, PMID 30971419 |
| Web CBT (ACTIB) | IBS-SSS at 12 months vs usual care | −35.2 (12.6–57.8), p=0.002 | same | Everitt 2019, PMID 30971419 |
| Nurse-delivered hypnotherapy | responders at post-treatment / 6 months / 1 year / 2 years | 64.3% / 62.8% / 64.7% / 61.8% | 207 of 289 completers | Lövdahl 2025, PMID 40491242 |
| Internet exposure-based CBT (routine care) | GSRS-IBS 48.06 → 33.06 at 6 months; Cohen's d 1.30 (1.08–1.51) | — | 309 consecutive patients | Wallén 2025, PMID 39194012 |
Microbiome interventions¶
| Intervention | Result | Source |
|---|---|---|
| FMT 30 g / 60 g vs placebo (own faeces), single donor | responders 23.6% / 76.9% (p<0.0001) / 89.1% (p<0.0001) | El-Salhy 2020, PMID 31852769 |
| FMT vs autologous, colonoscopic | primary endpoint not achieved in either group | Lahtinen 2020, PMID 32343000 |
| FMT vs placebo, duodenal, IBS-D | 57.1% vs 46.4% (p=0.42) — negative; bloating 72% vs 30% (p=0.005) | Yau 2023, PMID 37667968 |
| FMT (meta-analysis, 12 RCTs, 615 participants) | clinical response RR 1.44 (0.88–2.33) — not significant; certainty very low | Lo 2024, PMID 39289768 |
| FMT (Bayesian network meta-analysis) | OR 0.46 (0.33–0.64) — favourable | Wu 2024, PMID 38999862 |
| Probiotics (network meta-analysis) | OR 0.53 (0.48–0.59) | Wu 2024, PMID 38999862 |
| Probiotics (82 RCTs, 10,332 patients) | strain-specific; only 24 trials at low risk of bias; certainty low to very low across almost all analyses; adverse events not increased | Goodoory 2023, PMID 37541528 |
9. Placebo and nocebo¶
| Endpoint | Pooled placebo response | Source |
|---|---|---|
| Global improvement or abdominal pain (73 RCTs, 8,364 placebo patients) | 37.5% (34.4–40.6) | Ford 2010, PMID 20412064 |
| Global improvement (73 RCTs) | 27.3% (24.3–30.9) | Bosman 2021, PMID 33765447 |
| Abdominal pain | 34.4% (31.2–37.8) | Bosman 2021, PMID 33765447 |
| Composite FDA endpoint | 17.9% (15.2–21.0) | Bosman 2021, PMID 33765447 |
| IBS-C, FDA composite / pain / stool, ≥6 of 12 weeks | 18.9% / 34.6% / 30.1% | Barberio 2022, PMID 34425274 |
| IBS-C, same endpoints at ≥9 of 12 weeks | 4.3% / 24.5% / 7.7% | Barberio 2022, PMID 34425274 |
| IBS-D, FDA composite / pain / stool, ≥6 of 12 weeks | 16.2% / 40.2% / 16.2% | Barberio 2022, PMID 34425274 |
| IBS-D pain response at ≥30% / ≥40% / ≥50% improvement thresholds | 40.2% / 34.5% / 23.4% | Barberio 2022, PMID 34425274 |
| Nocebo: any adverse event on placebo (53 RCTs) | 32% (26–38); headache 9%, nasopharyngitis 7%, abdominal pain 4% | Li 2022, PMID 36606047 |
| Waiting list / limited placebo ritual / augmented practitioner relationship — adequate relief | 28% / 44% / 62% (p<0.001 for trend) | Kaptchuk 2008, PMID 18390493 |
| Open-label placebo vs no-pill control, IBS-SSS improvement | 90.6 vs 52.3 (p=0.038, d=0.43) | Lembo 2021, PMID 33605656 |
| Open-label vs double-blind placebo | 90.6 vs 100.3 (p=0.485, d=0.10) | Lembo 2021, PMID 33605656 |
10. Burden, quality of life and cost¶
| Measure | Value | Population | Source |
|---|---|---|---|
| IBS-QOL | 48.4 (SD 22.3) | 752 Rome IV IBS, UK | Goodoory 2023, PMID 36544055 |
| EQ-5D-5L | 0.570 (SD 0.283) — "comparable to people with stroke, leg ulcers or COPD" | same | Goodoory 2023, PMID 36544055 |
| SF-36 | Lower than US norms and than GERD, asthma, migraine; higher than panic disorder and rheumatoid arthritis | community and clinic samples | Frank 2002, PMID 12017411 |
| Absenteeism | 28.5% (133/467 employed) | 752 Rome IV IBS, UK | Goodoory 2022, PMID 35794733 |
| Presenteeism | 85.6% (373) | same | Goodoory 2022, PMID 35794733 |
| Overall work impairment | 81.8% (382) | same | Goodoory 2022, PMID 35794733 |
| Work hours lost per week | mean 1.97 | same | Goodoory 2022, PMID 35794733 |
| National extrapolation | 72–188 million hours/year lost, UK working age | same | Goodoory 2022, PMID 35794733 |
| Any activity impairment | 91.0% (684/752) | same | Goodoory 2022, PMID 35794733 |
| Absenteeism / presenteeism (independent cohort) | 24.3% / 86.8% | 525 IBS patients, Sweden | Frändemark 2018, PMID 30254230 |
| Direct cost per patient/year | US$193 (Korea) to US$31,113 (US, IBS-C), 2024 US$ | 33 studies, 14 countries, 1992–2022 | Neo 2026, PMID 42538760 |
| Indirect vs direct cost, Sweden IBS-C | US$17,112 vs US$1,943 | same | Neo 2026, PMID 42538760 |
| European direct cost | €1,837/year (1,480–2,195), range €1,183–3,358 by payer | 23 European datasets, n=15,157 | Flacco 2019, PMID 31002149 |
| European indirect cost | €2,314/year (1,811–2,817) | 13 datasets, n=3,978 | Flacco 2019, PMID 31002149 |
| European total cost | €2,889/year (2,318–3,460) | 11 datasets, n=2,757 | Flacco 2019, PMID 31002149 |
| US IBS-D all-cause cost | US$13,038/year; incremental vs matched controls US$2,268/year (78% medical, 22% pharmacy) | 19,653 commercially insured patients, 2013 | Buono 2017, PMID 28345443 |
| Highest-burden latent class | >£1,000/person/year IBS-related healthcare cost | UK community cohort | Black 2024, PMID 36858142 |
| Ever sought care for IBS | 68.2–73.2%; past 12 months 53.8–58.9% | Rome IV, US | Almario 2023, PMID 37595647 |
| Multiple doctor visits / hospitalisation (adjusted) | OR 2.08 / 1.78 | US veterans | Shin 2023, PMID 35964894 |
| All-cause mortality after IBS identification | HR 0.75 (95% CI 0.64–0.88) at >2–5 years; attenuated to 0.92 (0.87–0.98) after >17 years | NIH–AARP cohort, 132,697 participants; 5,030 with IBS; residual confounding remains plausible | Gutiérrez-Torres 2025, PMID 41518229 |
11. Stigma, psychological burden and safety¶
| Measure | Value | Source |
|---|---|---|
| Enacted stigma (randomised vignettes) | Higher toward IBS than toward IBD or adult-onset asthma; no IBD-vs-asthma difference | Taft 2017, PMID 27501483 |
| Negative comments about healthcare providers in expressive writing | 54% of 197 comments (11% positive, 35% neutral) | Halpert 2011, PMID 21561228 |
| "My HCP thinks I'm crazy" | 8% of comments | Halpert 2011, PMID 21561228 |
| Wanted vs received "comprehensive information" | 96% vs 38.3% | Halpert 2010, PMID 19513835 |
| Wanted vs received "listen" | 94.4% vs 63.8% | Halpert 2010, PMID 19513835 |
| Wanted vs received "support" | 88.6% vs 47.1% | Halpert 2010, PMID 19513835 |
| Misconception: IBS caused by lack of digestive enzymes | 52% | Halpert 2007, PMID 17488254 |
| Misconception: IBS can develop into cancer | 21.4% | Halpert 2007, PMID 17488254 |
| Contemplated suicide because of bowel symptoms — tertiary care | 38% | Miller 2004, PMID 15625650 |
| — secondary care / primary care / active IBD | 16% / 4% / 15% | Miller 2004, PMID 15625650 |
| Anxiety / depression / PTSD (adjusted OR) | 3.47 / 2.88 / 3.09 | Shin 2023, PMID 35964894 |
| Eluxadoline: sphincter-of-Oddi spasm | 10/1,839 (0.5%), all without a gallbladder | Cash 2017, PMID 27922029 |
| Eluxadoline: pancreatitis in registration trials | 5/1,666 (0.3%) | Lembo 2016, PMID 26789872 |
| Eluxadoline: pancreatitis share of post-marketing reports | 16.4% of 597, 53 hospitalisations; comparators 0.2–0.5% | Gawron 2018, PMID 28804032 |
| Tegaserod: coronary/cerebrovascular ischaemic events | 7 (0.06%) vs 1 (0.01%); OR 4.24 (0.52–34.74), p=0.273 | Lacy 2022, PMID 34048937 |
| Low FODMAP: faecal butyrate | 387.3 and 346.0 vs 609.2 (control) | Wilson 2020, PMID 32433273 |
| Low FODMAP: Actinobacteria | 1.9% and 1.8% vs 4.2% (control) | Wilson 2020, PMID 32433273 |
| Low FODMAP: total bacterial abundance | 9.63 vs 9.83 log10 copies/g (p<0.001) | Halmos 2015, PMID 25016597 |
12. Research activity (2026-09-02 snapshot)¶
| Metric | Value | Source |
|---|---|---|
PubMed records, irritable bowel syndrome |
21,184 | PubMed E-utilities, 2026-09-02 (re-verified this session) |
PubMed records, irritable bowel syndrome[MeSH Major Topic] |
9,618 | PubMed E-utilities, 2026-09-02 |
PubMed records, irritable bowel syndrome AND (microbiome OR microbiota) |
2,797 | PubMed E-utilities, 2026-09-02 |
PubMed records, irritable bowel syndrome AND placebo |
1,630 | PubMed E-utilities, 2026-09-02 |
| ClinicalTrials.gov registered IBS studies | 1,171 | ClinicalTrials.gov API v2, 2026-09-02 |
| — completed / recruiting / not yet recruiting / active not recruiting | 696 / 111 / 57 / 17 | same |
| — terminated / withdrawn / unknown status | 63 / 24 / 185 | same |
| — phase 1 / 2 / 3 / 4 / no phase | 43 / 177 / 105 / 80 / 592 | same |
| Condition-plus-intervention searches: probiotic / FODMAP / CBT / FMT | 133 / 97 / 50 / 37 | same |
| Condition-plus-intervention searches: rifaximin / linaclotide / hypnotherapy / amitriptyline | 26 / 27 / 22 / 4 | same |
Known conflicts and caveats¶
- Prevalence direction across criteria sets. Oka 2020 (PMID 32702295), Sperber 2021 (PMID 32294476) and Palsson 2020 (PMID 31917991) all find Rome IV prevalence roughly half Rome III. Ballena-Caicedo 2025 (PMID 41488823) finds Rome IV higher (17.14% vs 13.21%) and attributes it to a more precise pain definition. These are not reconcilable by averaging; they use different inclusion rules, and Oka's Rome IV pool contains only six studies.
- Heterogeneity is extreme almost everywhere. I² was 99.7% (Rome III) and 96.6% (Rome IV) in Oka 2020; 94–99% in the IBS–functional dyspepsia overlap meta-analysis (Andreev 2022, PMID 36286762); 78% for fibre symptom scores (Staudacher 2026, PMID 42600900). Pooled point estimates in this file should be read as centres of wide distributions.
- Quality-of-life comparisons contradict each other. EQ-5D places Rome IV IBS alongside stroke and COPD (Goodoory 2023, PMID 36544055); SF-36 places IBS below GERD, asthma and migraine but above rheumatoid arthritis and panic disorder (Frank 2002, PMID 12017411). Different instruments, eras and criteria.
- FMT effect estimates point in opposite directions. RR 1.44 (0.88–2.33), very low certainty (Lo 2024, PMID 39289768) versus OR 0.46 (0.33–0.64) (Wu 2024, PMID 38999862), over overlapping trial sets.
- Placebo response is endpoint-manufactured. The same trials give 34.6% (pain, 6/12 weeks) and 4.3% (composite, 9/12 weeks) placebo response (Barberio 2022, PMID 34425274). Any NNT quoted without its endpoint definition is uninterpretable.
- SIBO prevalence is test-manufactured. 54% by lactulose breath test, 31% by glucose breath test, 4% by jejunal culture in the same review (Ford 2009, PMID 19602448); 29.7% of healthy controls are breath-test positive (Shah 2020, PMID 31913194).
- Costs are not comparable across studies. Different health systems, cost definitions, criteria eras and inflation adjustments. Neo 2026 (PMID 42538760) adjusts to 2024 US dollars; Flacco 2019 (PMID 31002149) reports unadjusted euros for 2018 and earlier.
- Meta-analysis authorship is concentrated. A large share of the network meta-analyses summarised here originate from a single Leeds-based group, which also authored the BSG guideline. This is a consistency strength and an independence limitation, and it is stated rather than adjusted for.
- One value in section 6 is derived, not quoted. Kruis 1984 (PMID 6724251) reports two sensitivity/specificity operating points from the same weighted score; both are listed, neither is a headline figure from the abstract's conclusion.
- Registry status overstates activity. 185 of 1,171 ClinicalTrials.gov IBS records (15.8%) carry "unknown" status, meaning no update past the expected completion date.
Compiled 2026-09-02. All PMIDs verified live against PubMed E-utilities and all trial counts against the ClinicalTrials.gov v2 API during compilation.