Parkinson's disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease. While PD is typically characterized by motor symptoms such as bradykinesia, tremor, rigidity, postural instability, and gait disturbances, patients frequently present numerous non-motor symptoms, including gastrointestinal manifestations. These gastrointestinal symptoms may be fundamentally related to alpha-synuclein pathology, and dopaminergic treatments may further contribute to reduced gastrointestinal motility. Gastrointestinal symptoms can occur before the diagnosis of PD and at any stage during the disease course, affecting the gastrointestinal tract from the oral cavity to the anus. If left untreated, gastrointestinal problems can impair medication absorption, leading to motor fluctuations and potentially causing complications such as malnutrition and aspiration pneumonia, which may be life-threatening. Therefore, clinicians should not overlook gastrointestinal symptoms in PD patients. Gastrointestinal symptoms in PD can manifest diversely throughout the entire disease course, requiring healthcare providers to recognize these symptoms and provide individualized management. Since current treatments for PD-related gastrointestinal symptoms are largely derived from data in non-PD patients, future research and clinical guideline development in this field are required for establishing evidence-based care protocols.