Nausea and Vomiting The nausea and vomiting that occur thortly after administration of several of the drugs and frim trainal or abdominal radiation can be profound. The serotonin- receptor antagonists are effective in the cobtrol of nausea and vomiting occurring after emetogenic chemotherapy and radiotherapy. When conbined with dexamethasone, these agents are the tretment of choice in the prevention of delayed emesis.