Dyspepsia is one of the most common upper gastrointestinal symptom complexes. Its frequency depends heavily on how it is defined. Uninvestigated dyspepsia (upper GI symptoms without prior endoscopy) affects approximately 21% of adults worldwide, and about 80% of these individuals have no organic cause at endoscopy.^[1][2] Functional dyspepsia is a disorder of gut–brain interaction defined by Rome criteria.^[3] Rome-criteria functional dyspepsia has a global pooled prevalence of 8.4%.^[4] Under Rome IV criteria, the prevalence is 7.2% worldwide and 10.1% in the United States, with an annual incidence of approximately 3–4%.^[5][6] Functional dyspepsia is more common in women and in adults younger than 40 years. Its prevalence has declined over the past three decades, partly because successive Rome criteria have become stricter.^[4][6] Postprandial distress syndrome accounts for about two-thirds of cases. Overlap with irritable bowel syndrome and other disorders of gut–brain interaction is common. Functional dyspepsia also carries substantial healthcare utilization and economic burden.^[5][2]

• A meta-analysis of 100 study populations (312,415 subjects) estimated the global pooled prevalence of uninvestigated dyspepsia at 20.8% (95% CI 17.8–23.9%). Estimates ranged from 1.8% to 57.0% depending on country and definition.^[1]
• Approximately 80% of individuals with uninvestigated dyspepsia have no organic explanation at endoscopy. Community symptom surveys therefore serve as a reasonable proxy for functional dyspepsia burden.^[2]

• A 2024 meta-analysis of 44 studies (256,915 participants, 40 countries) found a global pooled prevalence of Rome-defined functional dyspepsia of 8.4% (95% CI 7.4–9.5%).^[4]
• Prevalence depends on the Rome iteration used. It is highest under Rome I and lowest under Rome IV, which reflects progressively stricter criteria rather than a true change in disease frequency.^[4]
• The Rome Foundation Global Epidemiology Study surveyed 54,127 internet respondents in 26 countries. It found a pooled Rome IV functional dyspepsia prevalence of 7.2%, ranging from 2.2% in Japan to 12.3% in Egypt.^[7][5]
• In the United States, the prevalence of Rome IV functional dyspepsia is approximately 10.1%. The estimated annual incidence is 3–4%.^[6]

^[4]

• The global prevalence of functional dyspepsia fell from 12.4% in studies conducted during 1990–2002 to 7.3% in studies conducted during 2013–2020.^[4]
• Proposed explanations include:
  • declining Helicobacter pylori prevalence
  • improved sanitation, with fewer post-infectious cases
  • better endoscopic detection, which reclassifies cases as organic disease
  • stricter Rome criteria
• Whether the decline is real or a methodologic artifact remains unsettled.^[4]
• Older epidemiologic figures based on Rome I–III or pre-endoscopy surveys therefore overstate the current Rome IV burden.^[4]

^[4]

• Under Rome IV, community prevalence is highest in young adults and declines with age. In the Rome IV Global Study, the odds ratio was 1.98 for ages 18–39 compared with ages 65 and older.^[5][6]
• This age gradient is the inverse of H. pylori infection, whose prevalence rises with age.^[4]
• Older patients are more likely to seek care, so clinical populations skew older than community populations.^[8]

• Functional dyspepsia is more common in women than in men regardless of the diagnostic criteria used (9.0% vs. 7.0%).^[4]
• Women are affected about 1.6 times as often as men.^[6] In the Rome IV Global Study, female sex was associated with both subtypes:^[5]
  • postprandial distress syndrome: OR 1.60 (95% CI 1.49–1.72)
  • epigastric pain syndrome: OR 1.42 (95% CI 1.27–1.59)

• Prevalence is modestly higher in developing countries than in developed countries (9.1% vs. 8.0%), with wide variation between countries.^[4]
• Ethnic differences are poorly characterized because most surveys sample ethnically homogeneous populations. A multiethnic Malaysian study found higher prevalence among Indian and Malay participants than among Chinese participants. This suggests cultural, dietary, and genetic contributions.^[2]

• In the uninvestigated-dyspepsia meta-analysis, classic risk factors showed only modest associations. The authors concluded that cultural, ethnic, genetic, and dietary factors may contribute more to community prevalence.^[1]
• Acute gastroenteritis roughly triples the odds of new functional dyspepsia more than 6 months later. Post-infectious onset accounts for at least 10% of cases.^[2][6]
• The association with anxiety and depression is bidirectional. About one-third of patients have anxiety, depression, or both.^[9][6]
• Heritability is weak, at approximately 5%.^[9]

^[1]

• In the Rome IV Global Study, postprandial distress syndrome (PDS) was the dominant subtype. It was followed by an overlapping PDS/EPS phenotype and then by epigastric pain syndrome (EPS) alone.^[5]
• Both subtypes decrease in prevalence with advancing age.^[5]
• Overlap with other disorders of gut–brain interaction is common among people meeting functional dyspepsia criteria:^[5]
  • Rome IV irritable bowel syndrome: 26.1%
  • functional heartburn: 9.0%
  • chronic nausea and vomiting syndrome: 7.0%
• Clinical series report IBS overlap in one-third to one-half of patients and GERD-symptom overlap in more than 30%. Overlap is associated with more severe symptoms.^[6]

^[5]

• In the Rome IV Global Study, 53.1% of individuals with functional dyspepsia had seen a physician for their symptoms. This included 39.9% who saw a primary care physician and 27.1% who saw a gastroenterologist.^[5]
• Care-seeking was highest in the overlapping PDS/EPS phenotype (70.1%), compared with about 34% for PDS alone or EPS alone.^[5]
• Medication use was roughly 2 to 2.5 times higher in people with functional dyspepsia than in those without it. Rates of cholecystectomy were also higher (see table below).^[5]
• Symptoms persist in roughly two-thirds of patients. Quality-of-life impairment is comparable to that of other chronic diseases.^[2]
• U.S. cost estimates exceed $5,000 per affected person per year and about $18 billion in aggregate.^[8][2]

^[5]

• Older reviews state that functional dyspepsia does not increase mortality.^[8]
• A 2026 review cites nationwide data suggesting increased risks of hospitalization and death, including suicide.^[6]

• Uninvestigated dyspepsia (about 20%) and functional dyspepsia (about 7–8%) are separate populations. Combining them inflates the functional estimate roughly threefold.^[1][4]
• Community burden skews young and female, while care-seeking populations skew older. Age alone should not lower clinical suspicion of organic disease.^[5][8]
• Prior gastroenteritis, active anxiety or depression, and overlapping IBS or GERD symptoms identify patients at higher probability of functional dyspepsia and greater symptom severity.^[2][6]