The main purpose of the study is to assess the efficacy of domperidone in treatment of functional dyspepsia (FD) in Chinese participants and identify sub-populations (subtype of the disease) who are sensitive to domperidone treatment.

Inclusion Criteria:

• Must meet the diagnostic criteria for functional dyspepsia (Postprandial Distress Syndrome [PDS] and/or Epigastric Pain Syndrome [EPS]) according to Rome IV diagnostic criteria for functional gastrointestinal disorders before and through screening
• Must have had an upper endoscopy that shows no evidence of structural change that is likely to explain the dyspepsia symptoms. If the participant has had the upper endoscopy performed within 3 months before screening, no re-test is needed
• Must have an abdominal ultrasonography that shows no evidence of organic disease that is likely to explain the dyspepsia symptoms. If the participant has the abdominal ultrasonography performed within 3 months before screening, no re-test is needed
• A woman of childbearing potential must have a negative serum (beta human chorionic gonadotropin [beta-hCG]) pregnancy test at Screening
• A woman must agree not to donate eggs (ova, oocytes) for the purposes of assisted reproduction during the study and for 30 days after receiving the last dose of study drug
• Otherwise healthy on the basis of physical examination, medical history, vital signs, and 12-lead electrocardiogram (ECG) performed at screening. If there are abnormalities, they must be consistent with the underlying illness in the study population. This determination must be recorded in the participant's source documents and signed by the investigator. Specifically, for vital signs, the participant must have blood pressure (after participant has been supine for 10 minutes) between 90 and 140 millimeter of mercury (mmHg) systolic (inclusive) and between 60 and 90 mmHg diastolic (inclusive)

Exclusion Criteria:

• Has a history of or current clinically significant medical illness including (but not limited to) cardiac arrhythmias or other cardiac disease, hematologic disease, coagulation disorders (including any abnormal bleeding or blood dyscrasias), lipid abnormalities, significant pulmonary disease (including bronchospastic respiratory disease), diabetes mellitus, renal or hepatic insufficiency, thyroid disease, neurologic or psychiatric disease, or any other illness that the investigator considers should exclude the participant or that could interfere with the interpretation of the study results
• Has history of risk factors for Torsade de Pointes or family history of short QT syndrome, long QT syndrome, sudden unexplained death at a young age (less than or equal to [<=] 40 years); or a history of second- or third-degree heart block
• Has clinically significant electrolyte disorders or conditions that result in electrolyte disorders, such as severe dehydration, vomiting, malnutrition, eating disorders, renal diseases, or the use of potassium-wasting diuretics or insulin in acute settings
• Has a history of esophageal, gastric, or duodenal surgery, including endoscopic surgery
• Has any condition in which stimulation of gastric motility might be dangerous, for example (e.g.), in the presence of gastrointestinal (GI) hemorrhage, mechanical obstruction, or perforation
• Has used any of the following medications 7 days before screening: proton pump inhibitors, antacids, anti-secretory agents, histamine2 receptor antagonists, gastric mucosa protective agents, digestive enzymes, prokinetic agents (including macrolide antibiotics), and other drugs that affect gastrointestinal function, QT-prolonging drugs, cytochrome P450 3A4 inhibitors, monoamine oxidase inhibitors (MAOIs), nonsteroidal anti-inflammatory agents, aspirin (including low-dose aspirin), anticholinergics, antidepressants, or diuretics