The New Rules For Diagnosing IBS, In Plain English

You’ve sat in front of a doctor trying to describe what your gut does. It’s hard to find the words. Some days it isn’t really pain. It’s more of a dragging, knotted, can’t-get-comfortable feeling that comes and goes. And part of you has wondered whether that even counts.

This year the specialists who write the international definition of Irritable Bowel Syndrome (IBS) changed it. One of the changes is about that exact feeling.

This page explains what changed, what stayed the same, and what it means for you.

Who decides what IBS is

There’s no blood test or scan that shows IBS. A doctor diagnoses it from your symptoms, after checking for other conditions that need ruling out.

So somebody has to agree which symptoms count. For researchers around the world, and for a lot of doctors, that’s the Rome Foundation. It’s a group of gut specialists who first met in Rome, which is where the name comes from.

Every ten years or so they go back through the research and rewrite the definitions. Each version gets a number. Rome IV came out in 2016. Rome V was published in May 2026 in the journal Gastroenterology, and more than 140 experts from 27 countries worked on it.

The Rome criteria are an agreement between experts about how to describe a pattern of symptoms. They get updated because the research moves on.

The new definition

Under Rome V, IBS means pain or discomfort in your abdomen that keeps coming back, but isn’t there all the time. It has to happen on at least 3 days a month on average, over the last 3 months. And it has to have started at least 6 months ago.

It also has to be linked to your bowels. At least two of these need to be true:

•it’s related to going to the toilet

•it comes with a change in how often you go

•it comes with a change in what your stools look like

What’s changed

Discomfort counts again. Rome IV only counted pain. If what you felt was more of an ache, or pressure, or an uncomfortable fullness, you didn’t fit the definition. Rome V puts discomfort back in.

The bar for how often is lower. Rome IV needed symptoms on at least one day a week. Rome V needs at least 3 days a month. If your IBS comes in bursts, a rough few days and then a couple of calmer weeks, you’re more likely to fit now.

Pain that never stops isn’t counted as IBS. The new wording says the pain or discomfort keeps coming back, but isn’t continuous. If your pain is there every single day and never eases off, Rome V doesn’t include it under IBS. That’s something to talk through with your doctor.

The words have changed. IBS used to be called a “functional” disorder. A lot of people heard that as “there’s nothing really wrong with you”. Rome IV started calling it a disorder of gut-brain interaction, which means your gut and your brain aren’t communicating the way they should. Rome V goes further. The authors say they’ve cut back on terms that are imprecise or stigmatising, and the group IBS sits in is now called bowel disorders, where it used to be functional bowel disorders.

Some of this has been here before

You might not expect this. The 3 days a month rule and the word discomfort aren’t new. They were both in Rome III, the version from 2006. Rome IV took them out in 2016.

So Rome V puts back what Rome IV removed, and adds one new line about continuous pain.

What’s stayed the same

The link to your bowels hasn’t changed. It’s the same list as before.

The types of IBS haven’t changed either. There’s IBS with constipation, IBS with diarrhoea, IBS with a mix of both, and IBS that doesn’t fit any of those. Your type is still worked out using the Bristol Stool Form Scale, a chart of seven kinds of stool.

And IBS is still a diagnosis a doctor makes after checking for other causes. Rome V doesn’t change that.

What this means for you in the UK

If you’ve already been diagnosed, nothing changes for you. Your diagnosis doesn’t disappear because the wording was updated.

If you’re in England, your GP probably isn’t using the Rome criteria anyway. Most GPs follow the National Institute for Health and Care Excellence (NICE) guideline on IBS, which has its own checklist. That checklist has included “pain or discomfort” since 2008. So the change that sounds biggest has been in your GP’s guidance all along.

Where you’ll see Rome V first is in research. Clinical trials use the Rome criteria to decide who can take part. That means the people in future IBS studies will be a slightly different group from the people in the last ten years of studies.

Researchers in Leeds and Boston have already started testing this. In a survey of UK adults with IBS, Rome V included more people than Rome IV, and on average their symptoms were milder. In a Leeds hospital clinic, Rome V picked up fewer of the patients whose IBS had been confirmed than Rome IV did, and the researchers said it isn’t yet clear what that means in practice. We look at the survey in more detail in this week’s post.

If you think you might have IBS and haven’t been diagnosed, start with your GP. The checks they do are there to rule out things that need treating differently. See your GP promptly if you notice bleeding from your bottom, weight loss you can’t explain, or symptoms that are new or getting worse, especially if you’re over 50.

Why it’s worth knowing

For years, a lot of people with IBS have wondered whether their symptoms were bad enough, or frequent enough, to count. If yours come and go, or feel more like discomfort than pain, the people who write the definition have now written you back in.

It doesn’t change what you feel. It might change how easy it is to describe it.

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. The 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, 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

•Disorders of Gut-Brain Interaction and the Rome V Process, Drossman, Chang and Tack, Gastroenterology, May 2026;170(6):1083-1098 (doi:10.1053/j.gastro.2026.02.014)

•Bowel Disorders, Corsetti et al., Gastroenterology, May 2026;170(6):1261-1282 (doi:10.1053/j.gastro.2026.02.003)

•Diagnosis and management of irritable bowel syndrome, Morrison and Talley, Australian Prescriber, June 2026;49(3):93-98 (sets out the Rome V criteria in full)

•Epidemiologic, Clinical, and Psychological Characteristics of Individuals With Self-Reported IBS Based on the Rome V vs Rome IV Criteria, Staller et al., Clinical Gastroenterology and Hepatology, 2026 (doi:10.1016/j.cgh.2026.07.022)

•The Rome V criteria for the diagnosis of irritable bowel syndrome in secondary care: a diagnostic accuracy study, Staller et al., The Lancet Gastroenterology and Hepatology, September 2026;11(9):812-820 (doi:10.1016/S2468-1253(26)00118-4)

•NICE CG61: Irritable bowel syndrome in adults, diagnosis and management

•Rome V: A Global Framework for Disorders of Gut-Brain Interaction, The Rome Foundation