Antiemetic drugs are prescribed to help with nausea and vomiting that are side effects of other drugs. This may include drugs for anesthesia used during surgeries or chemotherapy for cancer. Antiemetics include 5-HT3 antagonists, phenothiazines, and miscellaneous. 5-ht3 antagonists include dolasetron, granisetron, ondansetron, and palonosetron. These agents act by blocking the effects of serotonin at 5 HT3 receptor sites centrally as well as peripherally on vagal nerve terminals. Phenothiazines include chlorpromazine, prochlorperazine, and promethazine. Miscellaneous include dimenhydrinate, domperidone, meclizine, and metoclopramide. Uses, dosage, and side effects of all these drugs are also covered in this chapter.