Chronic nausea and vomiting syndrome: the definition, who gets it, and what to ask for

“You're not supposed to be nauseous all the time. You're not supposed to randomly throw up during the week. And you're not supposed to need a fistful of Zofran to get through it.”

Those three lines are the definition, in plain words. The Rome Foundation publishes the diagnostic criteria for disorders of gut-brain interaction, and the fifth edition came out in May 2026. For chronic nausea and vomiting syndrome, all of the following have to be true: bothersome nausea, meaning severe enough to affect your usual activities, on at least 2 days a week, with or without one or more vomiting episodes a week; self-induced vomiting, eating disorders, regurgitation and rumination ruled out as the cause; and nothing structural, systemic or metabolic found on routine investigation that would explain it. Two rules sort you into a neighbouring diagnosis instead: if the nausea is mainly after meals, with fullness or early satiety, that is functional dyspepsia; and if a gastric emptying study is delayed, the label becomes gastroparesis. The research criteria ask for 3 months of symptoms with onset at least 6 months before diagnosis. Rome's own clinical criteria, which it recommends over the research version in practice, drop that to 8 weeks when the symptoms are bothersome enough to seek care. On the Zofran line: it is a good drug for the night you need it, and I prescribe it. Needing it every week is a statement about the condition, not the drug.

Rome V, Gastroduodenal Disorders (Gastroenterology, May 2026)Rome V process paper, including the clinical criteria (Table 3)

“Somewhere between two and three million American adults. Three out of four are women. Most are under forty.”

The prevalence comes from a 2019 population survey of 5,931 adults in the United States, Canada and the United Kingdom, run by the Rome Foundation's epidemiology group: between 0.8% and 1.2% of adults met criteria, about the same in all three countries, and the Rome Foundation's later 26-country study put the worldwide figure at 0.9%. Against 267 million US adults, that is 2 to 3 million people. On who: in a Korean health-screening cohort of 5,096 adults, chronic unexplained nausea carried three times the odds in women and two and a half times the odds under age 40. In a 2024 Mexican gut-brain clinic cohort, 78% of the people with this syndrome were women and the median age was 26. In a New Zealand and US cohort tested with a gastric mapping device, 77% were women and the median age was 33. And most people who meet these criteria also meet criteria for a second gut-brain disorder at the same time, functional dyspepsia in 55% and irritable bowel syndrome in 41%, which is how the nausea ends up filed under something else.

Aziz et al., Clinical Gastroenterology and Hepatology 2019Jung et al., PLoS One 2019: 5,096 adults, SeoulFélix-Téllez et al., Revista de Gastroenterología de México 2024Science Translational Medicine 2023: gastric mapping cohortUS Census Bureau, Vintage 2024 adult population

“Nothing on the scope and nothing in the blood to explain it. It isn't your stomach lining. It's the wiring between your stomach and your brain.”

A normal workup is the usual result, not an unusual one. In the Korean cohort, everyone had an upper endoscopy, abdominal ultrasound, thyroid testing and blood work; about 1 in 4 of those with chronic nausea turned out to have something identifiable (reflux esophagitis, a duodenal ulcer, an overactive thyroid), and the other 3 in 4 had nothing to show for it. That is what "disorder of gut-brain interaction" means in practice: the structures look normal and the signalling between them doesn't behave. Rome V's description of the wiring is specific. Nausea is perceived in the insular cortex, amygdala, putamen and pons, the same regions that process threat and emotion, and vomiting is run by the dorsal vagal complex in the brainstem. The stomach reports in through the vagus nerve. Delayed emptying, the thing an emptying study measures, correlates poorly with how bad the nausea is.

Jung et al., PLoS One 2019Rome V, pathophysiology section

“There are treatments that work on that signal. For the reason, not just for tonight.”

I kept this line modest on purpose. Rome V's exact words are that "there has been scant investigation" of treatment for this syndrome. What it lists: antiemetics of several classes for the symptom, and, for the signal itself, low-dose tricyclic antidepressants and psychological therapies, which "show benefits in some patients with chronic nausea and vomiting." Tricyclics at nausea doses are used the way they are used for migraine prevention and nerve pain, as nerve-signal modulators, not as antidepressants. The psychological therapies are the brain-gut kind (cognitive behavioural therapy and gut-directed hypnotherapy), which have the strongest evidence in the neighbouring gut-brain disorders. Ginger, herbal remedies and electroacupuncture get a mention with "limited data." None of this is a prescription from a video. It is the list to bring to a gastroenterologist so the conversation can start somewhere other than the next refill. The cost of not having that conversation is measurable: in the Mexican cohort, people with this syndrome were about four times as likely to report their usual activities disrupted and to be at work but not functioning, and two and a half times as likely to miss work outright.

Rome V, treatment sectionFélix-Téllez et al. 2024: quality of life and work

“Ask for the name.”

Bring the count. "I've been nauseated at least two days a week since [month], I throw up about [n] times a month, my endoscopy and labs were normal. Do I meet criteria for chronic nausea and vomiting syndrome, and if I do, what's the plan besides the anti-nausea pill?" Two things make that sentence land. The first is the dates and the counts, which turn "I feel sick a lot" into a pattern a clinician can act on. The second is naming the diagnosis, because it moves the visit from "rule things out" to "treat what this is." If the answer is an emptying study, fine; if it is delayed, the label changes to gastroparesis and the conversation about the signal is the same one.