- Stimulation of the area postrema, which "senses" noxious chemical agents (e.g., poisons, chemotherapy agents, digoxin) and subsequently stimulates the vagal nuclei, which evokes nausea and coordinates the emesis reflex.
- Diseases of the central nervous system (CNS), such as infections or brain tumors, stimulate CNS structures and elicit nausea and vomiting, ultimately through vagal pathways.
- Diseases and disorders that originate in peripheral organ systems, such as the gastrointestinal tract, stimulate vagal or spinal afferent nerves that connect with the vagal sensory (tractus solitarius) and vagal efferent motor nuclei. Ultimately, cortical centers where nausea is perceived and the efferent pathways that mediate vomiting are stimulated.
- Tumors, infections, and drugs in the periphery may cause local dysfunction in a variety of organ systems that is sensed as nausea that, when severe, evokes vomiting.