Functional dyspepsia, also known as nonulcer dyspepsia, is a very common gastrointestinal disorder causing recurring or persistent upset stomach, for which after a medical investigation no cause has been determined. While this disorder is usually benign, it can lead to serious weight loss and food aversion that can result in malnutrition and hospitalization. Symptoms include recurrent intermittent or persistent upper abdominal pain or epigastric burning, abdominal bloating, eructation (belching or burping), postprandial fullness, early satiety, retching, and nausea. It is estimated to affect up to 20% of adults.

The Rome IV criteria for diagnosis of functional dyspepsia include one or more of the following for 3 months during the last 6 or more months: bothersome postprandial fullness, early satiety, epigastric pain, or epigastric burning. There also must be no evidence of systemic, metabolic, organic, or structural cause for symptoms, including on upper endoscopy. Additionally, symptoms are not relieved by defecation or flatus, and there are no stool irregularities.

The cause of functional dyspepsia is unknown and is likely multifactorial, including visceral hypersensitivity, undefined motility disorders, genetic predisposition, immune dysregulation, and biopsychosocial stressors. Functional dyspepsia is broken into 2 subtypes:

• Postprandial distress syndrome – Must have bothersome postprandial fullness, early satiety, or both. Eructation, postprandial epigastric burning or pain, bloating, and nausea may also be present.

• Epigastric pain syndrome – Must include bothersome epigastric pain, epigastric burning, or both at least 1 day per week. Pain is often induced by eating with bloating, nausea, and belching frequently present. Symptoms of gastroesophageal reflux disease (GERD) or irritable bowel syndrome (IBS) may coexist. 

The presence of recurrent vomiting or biliary pain should prompt evaluation for an alternative diagnosis.

Evaluation often consists of a thorough history and physical, esophagogastroduodenoscopy, and testing for Helicobacter pylori. Abdominal ultrasonography and colonoscopy are useful when symptoms indicate. Common laboratory studies including a CBC with differential, liver and kidney function studies, inflammatory markers, and thyroid functions are usually normal (unless abnormal due to another medical condition).

Associated nongastrointestinal symptoms include headache, irritable bladder, chest discomfort, sleep disorders, and excessive sweating.