There was a significant difference for nausea between the two groups (OR=3.01, 95 % CI=2.22-4.09, Z=7.08, P=0.00001), but no significant differences were observed for the other four adverse effects.CONCLUSIONS: For the treatment of major depressive disorder, our results show that a dose of 5 mg/day vortioxetine was more effective, but more easily induced nausea, compared to placebo.