Nausea and vomiting result from a wide variety of diverse causes. Nausea appears to be produced by stimulation of the central nervous system chemoreceptor trigger zone, which may be activated by a wide variety of drugs and endogenous stimuli. Vomiting is induced by stimulation of the vomiting center in the medulla, which receives input from the gastrointestinal tract, the cerebral cortex, the vestibular apparatus, and the chemoreceptor trigger zone. Complications of vomiting include dehydration, fluid and electrolyte disturbances (including metabolic alkalosis, hypokalemia, and hyponatremia), aspiration of vomitus, gastroesophageal mucosal laceration (Mallory-Weiss syndrome), and postemesis rupture of the esophagus (Boerhaave syndrome).