Motion Sickness and Vomiting Reflex

Abstract

Though many different pathologies cause vomiting, they can be divided into three categories. The first is vestibular vomiting such as that caused by motion sickness. The second is vomiting mediated by chemoreceptor trigger zone (CTZ) in the area postrema, such as that seen in poison-induced vomiting. The third is vomiting from the gastro-intestinal tract. Vestibular stimuli, signals from the CTZ, and afferent signals from the gastro-intestinal tract stimulate the vomiting center in the medulla to cause vomiting independently.
Histamine H₁-blockers (diphenhydramine, promethazine) prevent vestibular vomiting selectively. Dopamine D₂-blockers (metoclopramide, domperidone) act on the CTZ to inhibit CTZ-mediated vomiting. Serotonin 5-HT₃-blockers block afferent signals from the stomach induced by cisplatin. Diphenidol may inhibit the vomiting center because diphenidol prevents both motion and cisplatin-induced vomiting.