Functional heartburn (FH) is defined as retrosternal burning despite normal esophageal acid exposure on 24-hour pH monitoring and absence of major esophageal motor disorders or mucosal abnormalities like erosive esophagitis, Barrett’s esophagus, or eosinophilic esophagitis on endoscopy. This condition is often misdiagnosed as proton pump inhibitor (PPI)-resistant gastroesophageal reflux disease (GERD), leading to unnecessary long-term PPI use. Studies show FH accounts for 21–39% of patients with PPI-resistant heartburn, highlighting its prevalence in clinical practice. Unlike non-erosive reflux disease (NERD), FH does not involve acid as a primary cause, suggesting a different visceral hypersensitivity mechanism. Patients with FH often exhibit generalized gastrointestinal visceral hypersensitivity and a higher comorbidity with anxiety and other emotional disorders, indicating central processing abnormalities of sensory signals. Brain imaging studies reveal distinct neural activation patterns in FH patients compared to healthy individuals and GERD patients during esophageal stimulation. Diagnosis involves careful history taking to differentiate from other gastric symptoms, endoscopy with biopsy to rule out other esophageal diseases, and 24-hour impedance-pH monitoring to assess reflux and symptom association. Treatment aims to improve symptoms and quality of life and includes lifestyle modifications (though evidence is limited for FH specifically), neuromodulatorsNeuromodulators, and psychological interventions. PPIs are generally ineffective unless there is overlapping GERD. Surgical or endoscopic anti-reflux procedures should be avoided in FH due to poor outcomes. While FH typically does not lead to long-term organic complications, it significantly impairs patients’ quality of life. Future research is needed to establish long-term clinical courses and optimal treatments for this common condition.