ObjectiveTo systematically review the effect of dexamethasone in preventing post-operative nausea and vomiting (PONV) associated with epidural opioids for post-cesarean section analgesia. MethodsWe searched PubMed, EMbase, CNKI, WanFang Data and CBM databases from inception to Dec. 31th 2015, to collect randomized controlled trials (RCTs) comparing dexamethasone with placebo/blank for the prevention of PONV associated with epidural opioids for postcesarean section analgesia. Two reviewer independently screened literature, extracted data, and assess the risk of bias of included studies. Then, meta-analysis was conducted by using RevMan 5.3 software. ResultsA total of 11 RCTs from 10 papers involving 1 011 patients were included. The results of meta-analysis showed that, compared with the placebo/ blank group, the dexamethasone group had lower incidence rates of post-operative nausea (RR=0.50, 95% CI 0.39 to 0.65, P < 0.000 01), postoperative vomiting (RR=0.39, 95% CI 0.29 to 0.52, P < 0.000 01), PONV (RR=0.37, 95% CI 0.30 to 0.46, P < 0.000 01), and rescue antiemetic (RR=0.34, 95% CI 0.19 to 0.62, P=0.000 5). ConclusionsCurrent evidence indicates that dexamethasone is effective for preventing PONV after epidural opioids for post-cesarean section analgesia. Due to the limited quantity and quality of the included studies, the above conclusion needs to be further verified by more high quality studies.