Vomiting is controlled by the vomiting center in the medulla. Vomiting center is activated by either one of four trigger zones: chemoreceptor trigger zone, vestibular nuclei, cerebral cortex and gastrointestinal tract. Vomiting center is controlled by serotonin (5-HT3), muscarinic and histamine (H1) receptors.
Chemoreceptor trigger zone is sensitive to chemical stimuli, such as opioids and cytotoxic drugs. It is under the control of dopamine, serotonin (5-HT3) and opioid receptors.
Vestibular nuclei is controlled by muscarinic and histamine (H1) receptors. This is activated in vertigo or motion sickness.

Drug classes:

• 5HT3 receptor antagonists
• anticholinergic antiemetics
• miscellaneous antiemetics
• NK1 receptor antagonists
• phenothiazine antiemetics