For a long time, chronic constipation carried a name that hinted, without quite saying so, that it was not a proper illness. In clinical settings it was called functional constipation, and functional was the polite word for a complaint real enough to disrupt a life yet invisible on every scan. In May 2026, the people who write the diagnostic manual for these conditions removed that word.
The change comes from Rome V, the fifth edition of the Rome criteria, published in the journal Gastroenterology and edited by Douglas Drossman, Lin Chang and Jan Tack. Its larger idea is not new. A decade earlier, in Rome IV in 2016, the field adopted disorders of gut-brain interaction as its preferred description for this whole family of conditions, which includes irritable bowel syndrome and functional dyspepsia. What Rome V does in 2026 is narrower. It takes the word functional off the constipation label itself, so that functional constipation becomes, in the manual, chronic constipation.
We are writers, not clinicians. What follows is a reading of the reclassification and the science behind it, not medical advice. Rome V is a consensus framework assembled over seven years by a working group under the Rome Foundation, and it is not a single experiment. The biology it names is real. Parts of it are still being mapped.
What the change actually says
The retired word came with a history. Medicine has long split conditions into two boxes. Organic disorders show up on a test: a blockage, an inflammation, a tumour, something you can point at. Functional disorders were the leftover category, the symptoms with no visible cause, and they tended to attract the quiet suspicion that they were psychosomatic, or exaggerated, or in the patient’s head. People arrived with symptoms that had rearranged their days and left with a version of the sentence the Rome Foundation has spent three decades trying to retire: nothing is wrong.
The new name is an argument against that split. Symptoms come from a fault in the constant two-way signalling between gut and brain, it says, even when both organs look structurally normal on examination. On this reading a clear scan does not prove that nothing is happening; it locates the problem in the signalling rather than the plumbing.
The word has not vanished everywhere. Functional dyspepsia, the upper-gut condition marked by persistent fullness and discomfort with no ulcer or blockage to explain it, keeps its name in Rome V, and functional abdominal bloating keeps the term too. Constipation is one of the specific labels the committee chose to change, well short of a wholesale purge. Precision is the point here: a targeted edit, not a renaming of the field.
The line that runs both ways
The gut and the brain are not distant correspondents, and the traffic between them runs both ways.
The main physical cable is the vagus nerve. In the review literature, roughly 80 per cent of its fibres are afferent, meaning they carry information from the gut up to the brain, not commands from the brain down to the gut. Locally, the gut runs a good deal of its own chemistry too. Around 90 per cent of the body’s serotonin is produced in the gut wall, by specialised cells lining the intestine, not in the brain. Add the hormonal stress circuit known as the HPA axis, the immune signals moving through the bloodstream, and the metabolites made by the gut’s resident bacteria. Together these form a communication network with several overlapping channels.
A much-cited synthesis here is the 2021 review by Kara Margolis, John Cryan and Emeran Mayer in Gastroenterology, titled, plainly enough, “from motility to mood.” Their argument is that the same signalling governing how the gut moves also touches how a person feels, and the influence goes both ways. None of this means there is one clean pathway from a stressful week to a slow bowel. Mechanisms are several, they vary between people, and they are still being worked out. What the framework describes is a system, not a single confirmed switch.
What it does not mean
The most tempting misreading is the oldest one. Gut-brain interaction sounds, to a casual ear, like a sophisticated way of saying it is all in your head. In fact, the reverse is closer to the mark. The label exists to move these conditions out of the psychosomatic bin and to describe them as genuine disturbances in a physical signalling system. Read as a polite synonym for imaginary, it gets the intended meaning backwards.
Nor does the framework claim that stress alone causes constipation, or that a calmer life would resolve it. Stress is one input among many. And the reclassification does not sweep every case of slow or difficult bowel movement into the gut-brain category. Many cases fit this pattern; plenty do not. Constipation can also follow from a structural problem, a medication, a metabolic condition or a neurological one, and those are the causes a proper assessment is meant to find or rule out. A disorder of gut-brain interaction is, in part, a diagnosis reached once the tests come back clear.
Why the name matters in practice
A change of vocabulary in a diagnostic manual can look like housekeeping, and it is more than that.
The words a clinician writes in a chart shape which patients get enrolled in trials, which conditions insurers accept as real, and how a person is spoken to across a desk. Dropping functional removes a small, repeated insult that many patients had learned to expect.
The reframe also widens the set of treatments that make sense. If the trouble sits in that signalling, treatments aimed at it become reasonable to weigh alongside the familiar ones. The Rome Foundation lists gut-directed behavioural therapy, hypnotherapy aimed at the gut, and low doses of certain neuromodulators among the options for this family of conditions, sitting beside more conventional measures such as fibre and laxatives. Which of these suits any individual is a clinical judgement, not something a reader can settle from an article. What the new name does is make the wider menu coherent instead of eccentric.
Persistent changes in bowel habits are worth taking to a doctor rather than a search engine, partly for the reason above: constipation is sometimes the surface sign of something a scan needs to catch, and a reclassification in a manual is not a self-diagnosis tool. Anyone whose symptoms are lasting, worsening or new is better served by an assessment than by a label read at a distance.
What the change mostly does is finish correcting an old error of language. For years the terminology told a large group of people that their real and disruptive symptoms were somehow not quite legitimate, because the machine meant to find the cause could not see it. The reframing that arrived with Rome IV said that machine had been looking in the wrong place: the signalling between gut and brain is where a good deal of this had been happening all along. Rome V, a decade on, takes the last dismissive word off the constipation label. It has taken the field the better part of forty years, and five editions of a manual, to get the name right.
