The health benefits of citronella essential oil can be attributed to its possible properties as an antibacterial, antidepressant, antiseptic, antispasmodic, anti-inflammatory, deodorant, diaphoretic, diuretic, febrifuge, fungicidal, insect repellent, stomachic, stimulant, tonic, and vermifuge substance.
What is Citronella Oil?
Citronella is a grass that mainly grows in some Asian countries and some islands of the South Pacific. It has a rich, crisp lemony aroma and thus bears the name citronella. The essential oil of citronella is extracted from two varieties of citronella. The first one is the Ceylon variety, whose scientific name is Cymbopogon nardus and the second one is Java variety, called Cymbopogon winterianus in botanical terminology. In both cases, the essential oil is extracted by steam distillation of the fresh plant. 
Citronella Oil Nutrition
While the first variety yields an oil whose main components are citronellol, citronellal, geraniol, limonene, and methyl isoeugenol, the oil obtained from the second variety contains citronellal, geraniol, geranyl acetate, and limonene as its chief constituents, with geraniol and citronellal higher in concentrations than the former variety. Hence, the oil obtained from the Java variety is considered to be of higher quality. The main producers of this essential oil are China and Indonesia. This oil is also produced by certain other Asian, South & Latin American and African countries in smaller amounts. 
Health Benefits of Citronella Essential Oil
Apart from being used as a flavoring agent for foods and beverages, it has varied medicinal uses, which are listed below.
May Inhibit Bacterial Growth
According to a research report published in the Microbios Journal, components like methyl isoeugenol and a few others that are found in citronella essential oil are responsible for inhibiting any kind of bacterial growth. They kill bacteria and inhibit any further bacterial growth in the body. This is particularly helpful in treating infections in wounds, as well as in the colon, urethra, urinary bladder, stomach, intestines, urinary tracts, prostate, and kidneys. 
May Fight Depression
Citronella oil fights depression and gives relief from anxiety, sadness, and negative feelings. It induces a fresh, happy feeling and hope. 
May Eliminate Infections
The antiseptic properties of citronella essential oil fight infections in wounds, as well as the urinary tracts, urethra, prostate, and kidneys, while simultaneously protecting them from developing sepsis. 
May Relieve Spasms
Citronella essential oil relieves spasms of the muscles, respiratory system, and nervous system. KG Stiles, in his book, The Essential Oils Complete Reference Guide: Over 250 Recipes for Natural Wholesome Aromatherapy, mentions how the oil also helps to cure menstrual spasms and gives relief from symptoms such as cramps and coughs. 
May Have Anti-inflammatory Properties
A 2017 research paper published in the Evidence-Based Complementary and Alternative Medicine Journal states that citronella essential oil sedates inflammation, particularly those situations which pertain to the liver, stomach, intestines and other parts of the digestive system. The inflammations caused as side effects of drugs, excessive use of alcohol or narcotics, hard and spicy food, any disease, or any toxic element getting into the body can also be alleviated using this oil. 
May Remove Bad Odor
The crisp, rich citrus or lemon-like aroma of citronella oil drives away body odor and is used in deodorants and body sprays, although in very small quantities, since in heavy doses it may create skin irritations. It can also be mixed with the bathwater to have a refreshing bath. 
May Eliminate Toxins
The diaphoretic properties of citronella essential oil increase sweating and promote the removal of toxins and other unwanted materials like excess water, fat, and salts from the body. This makes the body feel lighter, keeps the skin healthy and also reduces fever. This also protects you from certain infections.
May Stimulate Urination
The increase in the frequency and quantity of urination due to this property of citronella essential oil has many benefits. A 2016 report published in the Scientific Research Journal states that it disposes of waste substances and toxins from the body, including uric acid, excess bile, acids, and salts, as well as water and fats. This helps reduce weight, eliminate infections in the urinary system, free the body from toxins, reduce chances of renal calculi, rheumatism, and arthritis, improve digestion, and keep the heart-healthy. 
May Reduce Fever
While the diaphoretic property of this oil increases perspiration, its anti-inflammatory property reduces inflammation, while the antimicrobial property fights infections. The combined effects of these three properties fight fever and reduce body temperature. 
Might Inhibit Fungal Growth
According to a 2014 report published in the Biological Research Journal, citronella oil kills fungus and inhibits fungal growth. This is very useful in countering fungal infections in the ear, nose and throat region. Contracting fungal infections in the ears are very common and can be very serious. It eliminates fungal infections in other parts of the body as well and helps cure fungal dysentery. 
May Act As an Insect Repellant
This is one of the most commonly used properties of citronella essential oil, as it kills and keeps away insects. It has been found particularly effective on a species of mosquito, called Aedes aegypti whose bite causes the dreaded yellow fever. This is also effective on lice, body and head louse, and fleas. 
May Prevent Stomach Disorders
The use of this oil clears the stomach from infections and other problems and helps it function properly. 
May Act As a Stimulant
The stimulating effect of the essential oil of citronella may stimulate blood circulation, secretions and discharges like hormones and enzymes from the glands, brain while also increasing activity in the nervous system. This essential oil also stimulates the immune mechanisms and the metabolism of the body. According to a study published in the Nutrients Journal in 2015, a group of obese rats was administered with citronella oil, following which it was noted that there was a significant fall in their body weight. The oil caused a decrease in the appetite of the rats, without any marked changes in liver enzyme concentrations. 
May Act as Tonic
This property may mean that citronella essential oil has an overall toning effect on the body. It tones up digestion, excretion, the nervous system, and the brain while fortifying the body.
May Kill Intestinal Worms
Citronella essential oil kills intestinal worms. It should be administered in mild doses to children since children are most prone to worms. It is effective on both roundworms and tapeworms. Since the presence of worms interferes with the normal physical and mental growth and also with the absorption of nutrients by the body, the use of this oil can greatly increase your quality of life by eliminating those dangerous parasites. 
Furthermore, citronella oil may be useful in the treatment of problems like oily skin, oily hair, abnormal palpitations, colitis, migraine, neuralgia, fatigue, headache, nausea, and abdominal pain resulting from gas or cramps.
Word of Caution: There is no inherent toxicity in the essential oil, but it has been seen to produce irritation, dermatitis or sensitization in the skin if used in high concentrations. It should not be used on the skin of small children and should be avoided during pregnancy.
Blending: The essential oil of citronella forms fine blends with the essential oils of cedarwood, clary sage, eucalyptus, geranium, lavender, lemon, peppermint, rosemary, and tea tree.