Effectiveness of citronella preparations in preventing mosquito bites: systematic review of controlled laboratory experimental studies.

This review aims to examine the effectiveness of citronella preparation used as a mosquito repellent. Multiple computerized databases such as MEDLINE, EMBASE, Cochrane CENTRAL, CINAHL, and AMED, were searched for controlled laboratory experiments that compared the effectiveness of citronella products to control in repelling Aedes, Anopheles and Culex mosquitoes using the cage or room methods. Outcomes measures were protection time and percentage repellency. The weighted mean difference and 95% confidence interval were calculated comparing the outcomes in the citronella and control groups. Meta-analysis was performed using the DerSimonian and Laird method under a random-effects model. Eleven studies met inclusion criteria. Based on a meta-analysis of studies using the cage method, protection time of the citronella oil for preventing Aedes mosquitoes was less than that in the DEET (N,N-diethyl-m-toluamide) group, with a difference in protection time of 253 min (95% confidence interval: 169-336). The combination of citronella oil and vanillin is likely to have a longer protection time compared with citronella oil alone. In studies using the room method, citronella oil and/or the combination of citronella oil and vanillin provided complete repellency at least 3 h. In Anopheles and Culex mosquitoes, a combination of citronella oil and vanillin product demonstrated a comparable protection time against DEET; however, it remained inconclusive due to a limited number of studies. Citronella products are less effective than DEET products in terms of duration of protection. Adding vanillin to citronella oil products could prolong the protection time.