Ernst, E., & Pittler, M.H. (2000). Efficacy of ginger for nausea and vomiting: A systematic review of randomized clinical trials. British Journal of Anaesthesia, 84, 367-71.
The review identified three studies on postoperative nausea, one for seasickness, one for morning sickness, and one for chemotherapy-induced nausea and vomiting (CINV). Studies were performed in the United States and in Denmark.
The total number of participants in the studies was 288 for postoperative nausea, 30 for morning sickness, 80 for seasickness, and 41 for CINV.
Clinical data was insufficient to draw a firm conclusion on the benefits of ginger for nausea and vomiting.
Although no adverse events were reported in these studies, ginger may have an adverse effect. A German monograph reported that ginger may be mutagenic in pregnancy.