the effect of ondansetron and dexamethasone on nausea and vomiting under spinal anesthesia

background during abdominal surgery under regional anesthesia, nausea may happen due to several contributing factors. this study compared the effects of ondansetron and dexamethasone on nausea and vomiting under spinal anesthesia. methods one hundred and twenty patients of 15 to 35 years old with asa class i and ii were enrolled. before administering either ondansetron or dexamethasone, blood pressure and heart rate of the patients were recorded. the patients received 70 mg of 5% lidocaine for spinal anesthesia. patients who received 6 mg of ondansetron were considered as group a, while group b received 8 mg of dexamethasone. the level of nausea and vomiting, blood pressure, heart rate and respiratory rate of each patient was measured at 1, 5, 10, 15 and 30 minutes after spinal anesthesia and during recovery (every 5 minutes). results there was a significant difference between nausea and vomiting between the two groups after spinal anesthesia within the first and fifth minutes. there was no significant difference between nausea and vomiting between the two groups within 10, 15 and 30 minutes and during recovery at 5, 10, 15 and 30 minutes. conclusion dexamethasone and ondansetron were shown to equally reduce the incidence of nausea and vomiting under spinal anesthesia and can be recommended as a good choice for prevention of nausea and vomiting during surgeries.