Lemon eucalyptus oil, the common name for one of the natural oils obtained from the lemon-scented gum eucalyptus plant, has gained popularity as an insect repellant. This use is important when you consider the dangers of DEET and other toxic solutions and want to steer clear of them. Learn more about the benefits, composition and proper therapeutic and practical applications of this plant oil.
What Is Lemon Eucalyptus Oil?
Lemon eucalyptus oil is extracted from the leaves and twigs of the lemon-scented gum eucalyptus plant, also known as Eucalyptus citriodora or Corymbia citriodora.
The lemon eucalyptus is a tall tree that grows up to 50 meters (164 feet) tall and comes from the temperate and tropical northeastern Australia.1 Its name is derived from the Latin term citriodorus meaning "lemon-scented," and is in demand for structural timber and for honey production. It is also popular in horticulture both in and outside of Australia.
The oil — particularly p-menthane-3,8-diol (PMD), its synthetic version with pesticidal properties — is used as an alternative to toxic mosquito repellents and most likely works by masking the environmental cues that mosquitoes use to locate their target.2 While the term "PMD" is often used interchangeably with lemon eucalyptus oil, know that it is different from the "pure" unrefined oil, which is typically used in making fragrances.
The refined lemon eucalyptus oil, which comprises related compounds from the plant, is known by its registered tradename "Citriodiol." However, it also has generic names varying by area, such as oil of lemon eucalyptus oil (OLE) in the United States and PMD rich botanic oil (PMDRBO) in Europe.
Uses of Lemon Eucalyptus Oil
Usually extracted through steam distillation, the essential oil3 has a pale yellow color and a thin consistency. It smells sweet, lemony and fresh, with a woody hint. Note, however, that this pure oil is not registered with the Environmental Protection Agency (EPA) as an insect repellant.
PMD, or the refined version, on the other hand, has a long history of use but only recently became important as a commercial repellent in the country. For many years, it has been used in China as a product called Quwenling, meaning "effective repellent of mosquitoes." American researchers initiated product investigation in the early 1990s and identified PMD as the active ingredient.
In 2000, the EPA registered oil of lemon eucalyptus or PMD as a "biopesticide repellent," meaning it is derived from natural materials. The resulting products can be applied to human skin and clothing for repelling insects such as mosquitoes, biting flies and gnats. They are formulated as a spray or a lotion.
Composition of Lemon Eucalyptus Oil
The essential oil of the lemon-scented gum mainly consists of citronellal (80 percent), produced mostly in Brazil and China.4 The refined oil's citronellal is converted into cis- and trans-isomers of PMD, a process that naturally occurs as the leaves of the plant age. Pure PMD is synthesized for commercial production from synthetic citronellal. Many other compounds have been identified and extracted from the lemon eucalyptus, including limonene and linalool.
Benefits of Lemon Eucalyptus Oil
Julia Lawless's Illustrated Encyclopedia of Essential Oils identifies a number of health benefits of lemon eucalyptus oil, which may help against arthritis, bronchitis, catarrh, cold sores, colds, coughing, fever, flu, poor circulation and sinusitis. Lemon eucalyptus or PMD can be a safe alternative to DEET, the most popular synthetic commercial insect repellent today. DEET has been documented to cause serious adverse effects, especially in children.
When it was tested on humans in Tanzania, PMD gave complete protection from biting for between six and 7.75 hours. Compared to DEET, there was no significant difference in efficacy and duration of protection when used against the Anopheles mosquito, the chief malaria vector in Africa. Other studies have also demonstrated its protection against the biting midge, deer tick and the stable fly.
Burning the leaves of the lemon-scented gum eucalyptus tree has therefore been shown as a cost-effective means of household protection, alongside the use of mosquito nets, in sub-Sahara Africa.
How to Make Homemade Lemon Eucalyptus Oil Insect Repellent
You can make a homemade mosquito repellent if you want to stay safe from DEET and other strong, toxic chemicals in most commercial repellents in the U.S. Lemon eucalyptus oil is considered key in making one, although you may also use citronella oil or cinnamon oil. Here is a recipe from Backpacking Spirit:5
Make your own mosquito repellent consisting of around 10 percent lemon eucalyptus oil. If you are using the essential ("pure") oil, note that it does not mix with water and will therefore require a carrier oil, such as coconut or olive oil.
- Obtain an appropriately sized bottle for travel; a 100 to 200 ml (3.3 to 6.76 ounces) bottle will be a good choice. You may also go for a bottle that has a spritzer nozzle for easy application.
- Choose your carrier oil or alcohol.
- Use a measuring jug for more precise measurements.
- For the 10 percent essential oil, if you are using a 100 ml bottle, mix 90 ml of your chosen liquid and 10 ml of lemon eucalyptus oil. If you are using a 200 ml bottle, mix 180 ml of liquid and 20 ml of essential oil.
- Shake the bottle thoroughly before use.
- Spritz onto skin and rub in.
- Store in a dark, cool place wherever possible and keep out of direct sunlight.
- Avoid the eye area.
- Reapply after exercise, swimming and from time to time throughout the day if you are outside.
- Get medical advice from your doctor about the best mosquito repellent for you. I advise not using eucalyptus lemon oil if you are pregnant.
How Does Lemon Eucalyptus Oil Work?
Lemon eucalyptus oil is applied topically on your skin for preventing mosquito and deer tick bites and may help with treating muscle spasms, toenail fungus (onychomycosis) and osteoarthritis and other joint pain. It is also added as an ingredient in chest rubs, which may help with congestion. Slate recommends6 this oil for repelling bugs:
"For full-on chemophobes who seek a registered product, there is lemon eucalyptus oil, which works as well as low concentrations of DEET and may last for up to six hours. For adventurous chemophobes, there is PMD, the synthetic version of lemon eucalyptus. Both are generally safe, although neither should be used on children under the age of 3 (just another example of the fact that natural doesn't always equal benign)."
Is Lemon Eucalyptus Oil Safe?
Lemon eucalyptus oil is generally safe for most adults when applied to skin as a mosquito repellent. Note, though, that some individuals might have a skin reaction to it. On the other hand, I strongly discourage internal applications of lemon eucalyptus oil as it is unsafe. Chest rubs for congestion contain lemon eucalyptus oil and can cause seizures and death if eaten.7
I advise pregnant and breast-feeding women to avoid using this oil, as not enough is known about the safety of using it while pregnant or breast-feeding.
Side Effects of Lemon Eucalyptus Oil
In EPA studies using laboratory animals, PMD showed no adverse effects, except for eye irritation. The technical material is categorized as an eye irritant, while the diluted end use products are estimated to be milder. Although rare, skin irritations can occur. As with any herbal oil, I suggest doing a skin patch test first to check if you're allergic to it.
As in using other plant or herbal oils, I recommend consulting a qualified natural healthcare practitioner if you are looking for therapeutic effects and benefits.