The New IBS Rules, And Who They Now Include
You’re filling in a questionnaire about your gut. It might be at the GP’s, or for a study you signed up to. It asks how often you’ve had stomach pain in the last three months, and the answers go up in steps. Every day. Every week. A few days a month.
You tick a few days a month. And you feel a bit of a fraud, because the bad days are properly bad, and there just aren’t that many of them.
For the last ten years, the definition most researchers used for IBS would not have included you. This year it changed. And a UK team has already looked at who the new definition includes.
This week’s research: more people count, and they’re a different group
First, a quick bit of background. Irritable Bowel Syndrome (IBS) is diagnosed from your symptoms, and the international definition comes from a group of gut specialists called the Rome Foundation. In May 2026 they published a new version, called Rome V.
It changed two big things. It counts stomach discomfort as well as pain. And it needs symptoms on at least 3 days a month, where the old version, Rome IV, needed at least one day a week. There’s one new exclusion too: if your pain is there all the time and never lets up, Rome V doesn’t count it as IBS. I’ve written a separate page that goes through every change, The New Rules For Diagnosing IBS, In Plain English.
This week’s study tested what those changes do to real people. It was led by Kyle Staller at Massachusetts General Hospital in Boston, working with Alexander Ford and Christopher Black in Leeds. It was published online in July 2026 in the journal Clinical Gastroenterology and Hepatology.
The team surveyed 1,275 adults in the UK who had told a research register they had IBS. Everyone filled in the questionnaires for three versions of the Rome definition: the old Rome III from 2006, Rome IV, and the new Rome V. They also answered questions about how severe their symptoms were, their quality of life, and psychological symptoms such as anxiety and low mood.
Here’s how many people fitted each version:
•Rome III: 995 people, 78 per cent
•Rome IV: 752 people, 59 per cent
•Rome V: 893 people, 70 per cent
So Rome V counted more people than Rome IV did. That’s what you’d expect from a lower bar.
The more interesting part came next. When the team compared the Rome V group with the Rome IV group, the Rome V group had less severe symptoms on average. They had fewer psychological symptoms. Their IBS got in the way of work and social life less, and they scored higher on quality of life.
The authors say the main reason is the new exclusion. Rome V leaves out people whose pain is there every day, and those tend to be the people struggling most. So the new definition takes in more people with on-and-off symptoms, and sets aside some of the people with the heaviest ones.
When the team checked back with people later, the Rome V group was also less stable. More people moved in and out of the definition over time than under Rome IV. That fits with symptoms that come and go.
Now the limits. Everyone in this study said they had IBS. None of them was examined in a clinic as part of the study. Most of the people who took part were women, and nearly all were white, so it can’t tell us much about everyone with IBS. And it’s a survey, so it shows who fits which definition. It doesn’t show which definition is more useful to a doctor.
Why this matters for you. If your IBS comes in bursts, or feels more like discomfort than pain, you’re more clearly inside the definition than you were a year ago. If your pain never eases at all, Rome V puts you outside the IBS label, and that’s worth raising with your GP. Either way, when you read about new IBS trials from here on, the people in them may have fewer symptoms than the people in the trials you’ve read about before.
Milder on paper doesn’t mean easy to live with
A study like this measures symptoms. Pain on how many days. Severity on a scale.
What it can’t measure well is what happens on the days in between. You’re checking where the toilets are before you’ve agreed to meet a friend. You’re skipping lunch before a long drive. You’re lying awake the night before a meeting, wondering whether tomorrow’s one of the bad days. None of that shows up as a symptom day, and it can take up a lot of your life.
IBS is described as a disorder of gut-brain interaction. Your gut and your brain send messages to each other all the time, and in IBS that conversation has become oversensitive. We looked at what that feels like from the inside in Why You Feel Almost Every Emotion In Your Stomach. The watching and the planning are part of that loop too. Your brain learns to stay on guard for your gut, even on a quiet day.
That’s where my work fits. I’m a cognitive behavioural hypnotherapist, which means I use three things together. Cognitive behavioural therapy works on what you expect a feeling in your gut to mean, and what you do next because of it. Mindfulness trains your attention to notice a feeling for what it is. Gut-directed hypnotherapy uses focused attention and imagery aimed at the gut. They all work on the same loop. The British Society of Gastroenterology gives gut-directed hypnotherapy a strong recommendation for IBS, and NICE lists psychological approaches including hypnotherapy for IBS that hasn’t responded to medication after twelve months. I can’t tell you what it would do for you, and this week’s study didn’t look at treatment at all. What it does show is that a lower symptom count and an easy life aren’t the same thing.
Your top tip this week
Keep a one-line gut diary for a month. Each evening, write one line. Did you have any stomach pain or discomfort today, yes or no? And if yes, did it have anything to do with going to the toilet? Don’t score it and don’t write about what you ate. At the end of the month you’ll have your own count, which is what the new definition asks about, and a clear record to take to your GP instead of trying to remember. You’ll also have the good days written down, which are easy to forget when a bad one is happening.
The takeaway
The rules for what counts as IBS changed this year, and more people with on-and-off symptoms now fit them. If you’ve spent years feeling your IBS wasn’t frequent enough to take seriously, the definition has caught up with you.
Wherever you are right now
If you haven’t had a firm diagnosis yet, start with your GP. The checks they do rule out what needs ruling out, and the one-line diary above gives you something clear to show them.
If you were diagnosed a while ago and you’re still struggling, nothing about your diagnosis changes. For the full picture of what Rome V does and doesn’t change, read The New Rules For Diagnosing IBS, In Plain English.
If you’re a GP or a gastroenterologist reading this, the referrer brief for gut-directed hypnotherapy, with the guideline positions set out and their limits stated, is available on request.
If you’d like the science in plain English once a week, plus one thing to try, join Gut Feelings at mindyourguts.co.uk/free-relaxation-page. A free relaxation recording comes with it.
About Mind Your Guts
Mind Your Guts is the Irritable Bowel Syndrome (IBS) blog written by Kathryn Dunn, a cognitive behavioural hypnotherapist based in York and working online. One piece of gut-brain research each week, in plain language, and one thing worth trying. More at mindyourguts.co.uk/gut-feelings.
Twelve Minutes of Calm. A free relaxation recording, about twelve minutes long, for the times you want to feel calmer. It’s a general relaxation recording rather than a treatment for anything. Download it at mindyourguts.co.uk/free-relaxation-page and you’ll also join Gut Feelings, my weekly email, which carries each new post to your inbox along with a bit extra.
Hypnotherapy works alongside conventional medical care, never in place of it. This blog shares research for general information and is not a substitute for medical advice. Only a doctor can diagnose IBS. Always consult your GP or another relevant health professional. If your symptoms are new, changing, or accompanied by warning signs such as bleeding, unexplained weight loss, or persistent pain, please see your GP.
Sources
•Epidemiologic, Clinical, and Psychological Characteristics of Individuals With Self-Reported Irritable Bowel Syndrome Based on the Rome V vs Rome IV Criteria, Staller, Goodoory, Ng, Ford and Black, Clinical Gastroenterology and Hepatology, published online 30 July 2026 (doi:10.1016/j.cgh.2026.07.022, PMID 42532244)
•Bowel Disorders, Corsetti et al., Gastroenterology, May 2026;170(6):1261-1282
