The normal function of the gastrointestinal (GI) system is regulated and controlled by the central nervous system. The parasympathetic and sympathetic nervous systems play a role in gastrointestinal muscle movements, tone, motility, and mucosal secretions, especially in the stomach and esophagus. The nature of the gastrointestinal and neuronal relationships makes the GI system susceptible to conditions causing symptoms such as nausea, vomiting, diarrhea, and constipation. In this chapter, drugs used to treat and manage these symptoms will be discussed.