The National Pesticide Information Center states that oil of lemon eucalyptus is the only one essential oil recommended by the CDC as an effective alternative to DEET. They site that it has a similar protection time as DEET with fewer undesirable effects although its mechanism of action is unknown. The CDC has stated that lemon eucalyptus oil has ”been shown to offer long-lasting protection against mosquito bite” since 2005.
The CDC says that it is best to avoid mosquito bites by using insect repellents. They list repellents containing oil of lemon eucalyptus among DEET, picaridin, and IR3535 as effective repellents. The CDC states that oil of lemon eucalyptus, also called p-menthane 3,8-diol or PMD, is a plant-based mosquito repellent that provides similar protection to low concentration DEET products.
Oil of lemon eucalyptus is an extract of the Australian eucalyptus tree. Concentrated extracts of the are called para-menthane-3,8-diol, or PMD. The Environmental Working Group (EWG) states that PMD oil is very different from oil of lemon eucalyptus products containing oil of lemon eucalyptus.
The EWG states that science has not yet determined the differences between PMD and oil of lemon eucalyptus, but studies found that “Oil of Lemon Eucalyptus provides longer protection than the equivalent concentration of synthetic PMD.” Synthetic PMD is often found in concentrations of 10 percent and only provides a few hours of protection. The EWG states that there is a warning against using these products on children under 3, but they present less risk of skin reaction than natural PMD.
“Most Oil of Lemon Eucalyptus products on the market are made by Spectrum Brands and sold under the brand names Repel and Cutter. These have concentrations of 30 percent Oil of Lemon Eucalyptus and 20 percent PMD. Some testing has shown that concentrations of 20 to 26 percent PMD may perform as well as 15 to 20 percent DEET against both mosquitoes and ticks,” stated the EWG.
These findings are supported in a repellent product guide by the National Pesticide Information Center. The NPIC compared commercial repellents, and their data shows that OFF! Botanicals Insect Repellent with 10.0% PMD offers effective mosquito repellent for 2 hours while products that contain 30% Oil of Lemon Eucalyptus, such Repel Essential Insect Repellent, offer 6 hours of protection.
In addition to using insect repellent, the CDC suggests wearing long sleeve shirts and pants when weather permits and to apply repellents on top of clothing, not on skin. They say never use repellents over cuts, wounds or irritated skin or around the eyes or mouth and use sparingly around ears.
The CDC recommends “when using repellent sprays, do not spray directly on your face—spray on your hands first and then apply to your face. Do not allow children to handle or spray the product. When using on children, apply to your own hands first and then put it on the child. Avoid applying repellent to children’s hands because children frequently put their hands in their eyes and mouths.”
“Use just enough repellent to cover exposed skin and/or clothing. Heavy application does not give you better or longer lasting protection. After returning indoors, wash treated skin with soap and water or bathe,” the CDC states.
Oil of Lemon Eucalyptus is not the same as lemon eucalyptus essential oil. Essential oils are way stronger and need diluted with a carrier oil. Recipes vary, but many claim repellent can be easily made at home by combining a few drops of essential oil with a carrier oil, alcohol, and vanilla extract.