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Citronella

Also known as: Citronella, citronella oil, Cymbopogon winterianus, lemongrass oil, Cymbopogon nardus

Overview

Citronella oil is an essential oil primarily extracted from the leaves and stems of *Cymbopogon nardus* and *Cymbopogon winterianus*, tropical grasses known for their strong lemon-like aroma. It is widely recognized and utilized as a natural mosquito repellent, offering a safer alternative to synthetic chemicals. Beyond its insect-repelling properties, citronella oil is also employed in aromatherapy for its potential to alleviate anxiety and stimulate appetite. Its key active constituents include citronellal, citronellol, and geraniol, which contribute to its characteristic scent and biological activities. While extensive research supports its efficacy as a mosquito repellent, evidence for its aromatherapy benefits is emerging, and clinical trials for other therapeutic uses, such as antimicrobial and antifungal properties, are still limited. The overall quality of evidence for mosquito repellency includes meta-analyses and controlled trials, whereas aromatherapy effects have fewer high-quality randomized controlled trials.

Benefits

Citronella oil offers several evidence-based benefits, primarily as a natural insect repellent. A meta-analysis of 11 controlled studies demonstrated its significant repellency against various mosquito species (*Aedes*, *Anopheles*, and *Culex*), although its protection duration is shorter than DEET, typically by about 253 minutes. Combining citronella oil with vanillin can extend its protection time, sometimes making it comparable to DEET in specific studies. This makes it a valuable option for individuals seeking natural alternatives for mosquito control. In the realm of aromatherapy, a recent randomized controlled trial showed that citronella oil significantly improved appetite scores in a vulnerable pediatric population, suggesting its potential in appetite stimulation. While less robust, there is also some indication that citronella aromatherapy may help reduce anxiety. Furthermore, in vitro studies and reviews suggest that citronella oil possesses antimicrobial and antifungal properties, but clinical evidence to support these uses in humans is currently limited and not yet conclusive.

How it works

Citronella oil's primary mechanism as a mosquito repellent involves its volatile compounds, such as citronellal and citronellol. These compounds interfere with the olfactory receptors of mosquitoes, effectively masking human scents and deterring them from biting. In aromatherapy, the pleasant aroma of citronella oil is believed to modulate the limbic system in the brain, which influences emotional states and physiological responses like appetite and anxiety. For its potential antimicrobial effects, the constituents of citronella oil are thought to disrupt microbial cell membranes and inhibit their growth, although the precise molecular targets and pathways are not yet fully elucidated.

Side effects

Citronella oil is generally considered safe when used topically or in aromatherapy at recommended doses. The most common side effects are localized skin reactions, including irritation, dermatitis, and eczema, which have been reported in a minority of sensitive individuals (less than 5%). These reactions are typically mild. There have been no reports of significant systemic toxicity from sub-chronic animal studies at typical exposure levels, indicating a favorable safety profile for external use. There are no well-documented drug interactions with citronella oil; however, caution is advised when using it concurrently with other skin sensitizers. Citronella oil is contraindicated in individuals with a known allergy or hypersensitivity to citronella or other related essential oils. For special populations such as pregnant or breastfeeding women, data is limited. While animal studies suggest low toxicity, human data are lacking, and therefore, use in these groups should be approached with caution and ideally under medical supervision. Undiluted oil should always be avoided on the skin to prevent irritation.

Dosage

For mosquito repellency, citronella oil is applied topically in various formulations. The duration of protection is dose-dependent and can be significantly enhanced by combining it with additives like vanillin. Due to its volatility, reapplication every 1-2 hours is generally recommended to maintain efficacy. In aromatherapy, typical inhalation doses involve diffusing a few drops of the oil in a diffuser device. Clinical studies on appetite stimulation used controlled aromatherapy sessions, but exact dosing protocols can vary. Aromatherapy sessions typically last between 15-30 minutes. A maximum safe dose for citronella oil has not been definitively established, particularly for internal use, which is not recommended without medical supervision. For topical application, it is crucial to avoid using undiluted oil to prevent skin irritation and sensitization. Always dilute citronella oil with a carrier oil before applying it to the skin.

FAQs

Is citronella as effective as DEET?

No, citronella provides a shorter duration of protection compared to DEET. However, it is a natural alternative with fewer chemical concerns, and its efficacy can be improved when combined with other compounds like vanillin.

Can citronella oil be ingested?

Ingestion of citronella oil is generally not recommended due to a lack of comprehensive safety data and potential for adverse effects. It should only be considered under strict medical supervision.

How quickly does citronella work for appetite stimulation?

Aromatherapy studies suggest that effects on appetite may become noticeable after repeated sessions over several days, rather than immediately. More research is needed to establish the precise onset and duration of effect.

Is skin irritation common with citronella oil?

Skin irritation occurs in a minority of sensitive individuals. It is advisable to perform a patch test on a small area of skin before widespread topical use, and always use diluted oil.

Research Sources

https://hsij.anandafound.com/journal/article/download/47/33/286 – This randomized controlled trial (Kasmirah et al., 2025) investigated the effect of citronella oil aromatherapy on appetite in a pediatric population. The study found that aromatherapy significantly improved appetite scores, with a large effect size, suggesting a potential benefit for appetite stimulation in vulnerable children. The study design was controlled, but limitations included a single population and short-term outcomes.
https://pubmed.ncbi.nlm.nih.gov/21481108/ – This systematic review and meta-analysis (Kongkaew et al., 2011) synthesized data from 11 controlled laboratory studies comparing citronella oil to controls and DEET for mosquito repellency. It concluded that citronella oil is less effective than DEET in terms of protection duration, but its efficacy can be improved when combined with vanillin. The study was high quality, but noted variability in methods and limited human field trials.
https://ecommons.cornell.edu/bitstream/handle/1813/56119/citronella-MRP-NYSIPM.pdf – This toxicology review (Baker et al., 2018) provides a comprehensive safety profile of citronella oil, based on sub-chronic toxicity data from rodent and human studies. It concluded that citronella oil exhibits no significant systemic toxicity at typical exposure levels but highlighted its potential for skin sensitization in some individuals. The review is considered high quality due to its comprehensive nature.
https://www.semanticscholar.org/paper/REVIEW-ARTICLE-CHEMICAL-ANALYSIS-AND-THERAPEUTIC-OF-Wany-Jha/fdf6c2798db5c23b8900e483785363167093c908 – This review article discusses the chemical analysis and therapeutic properties of citronella oil, including its antimicrobial and antifungal activities. It suggests that citronella oil constituents can disrupt microbial cell membranes and inhibit growth, though it emphasizes that clinical evidence for these applications is still limited and not yet conclusive.
https://pmc.ncbi.nlm.nih.gov/articles/PMC9826021/ – This source provides further insights into the mechanism of action of citronella oil, particularly its volatile compounds like citronellal and citronellol. It explains how these compounds interfere with mosquito olfactory receptors, effectively masking human scents and deterring bites, contributing to its efficacy as an insect repellent.