Citronella oil is popular as a "natural" insect repellent. Its mosquito repellent qualities have been verified by research, including effectiveness in repelling Aedes aegypti (dengue fever mosquito).
The US Environmental Protection Agency states that citronella oil has little or no toxicity when used as a topical insect repellent, with no reports of adverse effects of concern over a 60-year period If used according to label instructions in the US, citronella is not expected to pose health risks to people, including children and other sensitive populations. The US Food & Drug Administration considers citronella oil as generally recognized as safe (GRAS).
IN EUROPE, Citronella oil was formally approved on 1 September 2009 and will expire on 31 August 2019.
Citronella oil is one of the essential oils obtained from the leaves and stems of different species of Cymbopogon (lemongrass). The oil is used extensively as a source of perfumery chemicals such as citronellal, citronellol, and geraniol. These chemicals find extensive use in soap, candles and incense, perfumery, cosmetic, and flavouring industries throughout the world.
Citronella oil is also a plant-based insect repellent and has been registered for this use in the United States since 1948.
Citronella works by masking scents that are attractive to insects namely carbon dioxide and lactic acid in humans according to the NPIC.
One benefit of using citronella as mosquito repellent is that it is safe and non-toxic to humans and animals (and even the insects). Although some people can have mild allergic reactions to the oil, even ingesting citronella will not affect humans it is simply broken
down and passed out of the body through urine. Citronella oil works by repelling mosquitoes from the skin and do not kill any mosquitoes. It masks scents that mosquitoes are sensing, so when a citronella oil is applied to the coil it blocks scents and they cannot be sensed by mosquitoes. These scents are carbon dioxide and lactic acid. Generally, insects will have much more difficult time locating you, when a citronella coil is ignited.. Some resources also suggests that citronella oil repels not only insects but also animals, but this is not scientifically proven.