How to use it
- Alarm features first. Tick any that apply, or tick “None of these”. Any alarm feature turns the result red and lists targeted tests. The treatment list stays hidden until it’s investigated.
- Rome V criteria. Ask about the past 3 months, on average. The tool works out Rome V and Rome IV from the same answers.
- Subtype. Use the patient’s report of what their abnormal stools usually look like (fine for clinic), or enter counts from a 2-week stool diary. The 25% rule is applied for you. Subtype off laxatives and antidiarrheals.
What changed in Rome V (2026)
| Rome IV (2016) | Rome V (2026) | |
|---|---|---|
| Symptom | Abdominal pain | Abdominal pain or discomfort |
| Frequency | ≥1 day a week | ≥3 days a month |
| Continuous pain | Allowed | Excluded (think centrally mediated abdominal pain syndrome) |
| Associated features | ≥2 of: related to defecation, change in frequency, change in form | Same |
| Timing | Last 3 months, onset ≥6 months before | Same |
| Menses | Not addressed | Supportive: not only related to menses |
| Subtypes | 25% rule on abnormal days | Same, plus a patient-report option for IBS-U |
Rome V picks up more people, and they are milder on average. In a UK survey of people with self-reported IBS, Rome V captured 70% and Rome IV 59% (Staller 2026). Most trials of current IBS drugs used Rome III or IV, so a patient who meets only Rome V may respond differently.
“Continuous” means pain present all the time while awake (Rome V, centrally mediated pain chapter).
Reading the result
| Result | What to do |
|---|---|
| Rome V met, no alarm features | Make a positive diagnosis. Limited tests: celiac serology (tTG-IgA with total IgA) and CBC; CRP optional; fecal calprotectin if there is diarrhea. |
| Any alarm feature | Investigate the feature first. Onset at age 50 or older: colonoscopy (CAG statement 6). |
| Rome IV met, Rome V not met | The pain is continuous: consider centrally mediated abdominal pain syndrome. |
| Not met | Think about functional constipation, functional diarrhea, functional bloating, or another diagnosis. |
Where the guidelines disagree
- Calprotectin and CRP. CAG 2019 recommends against routine fecal calprotectin and CRP (statements 2–3). ACG 2021 suggests calprotectin and CRP for suspected IBS with diarrhea, and Rome V lists calprotectin as a selective stool test while listing CRP, with CBC and celiac serology, among the blood tests for all patients (figure 4). This tool suggests calprotectin when diarrhea is present and lists CRP as optional: it is not required by CAG 2019, but Rome V lists it and a normal CRP makes IBD less likely.
- Colonoscopy. CAG: not routinely under 50 without alarm features (statement 4, strong), and not routinely even with alarm features under 50 (statement 5, conditional), so target the test to the feature. ACG: not routinely under 45 without warning signs.
- Rifaximin. CAG 2019 made no recommendation for or against one course in IBS-D (no recommendation C). It cited antibiotic resistance, cost and overuse, and advised referral to a gastroenterologist if it is tried. ACG 2021 recommends it (strong, moderate quality).
- Antispasmodics and probiotics. CAG suggests both (conditional). ACG suggests against both for global symptoms. The antispasmodics CAG found effective (hyoscine, pinaverium, dicyclomine) are available in Canada.
Pitfalls
- Subtype off treatment. Laxatives and loperamide change stool form. Subtyping is more reliable with at least 4 days of abnormal bowel habits a month.
- Exactly 25%. The rule is “more than” and “less than” a quarter. Exactly 25% hard stools is neither, so the tool calls it IBS-U.
- Eluxadoline. Contraindicated after cholecystectomy, and with biliary obstruction, alcohol misuse, pancreatitis, hepatic impairment or severe constipation (CAG 2019).
- Canadian availability (Health Canada, October 2026). Lubiprostone was never marketed in Canada, and tenapanor (Ibsrela) was cancelled in June 2026. Alosetron and tegaserod are not available. Linaclotide (Constella) and plecanatide (Trulance) are marketed.
- Screening isn’t IBS work-up. Anyone aged 45–74 at average risk should be up to date with Ontario’s FIT program. See the polyp surveillance tool for family-history rules.