Ingredient Investigator: Oil of Lemon Eucalyptus in Bug Sprays

    This naturally derived active ingredient can be effective in certain insect repellents and is safe when used correctly

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    Repel Lemon Eucalyptus Insect Repellent2, Cutter Lemon Eucalyptus Insect Repellent Aerosol and Natrapel Lemon Eucalyptus Insect Repellent Pump Photos: Consumer Reports

    One question we get a lot here at CR: Are there any effective bug sprays that don’t contain deet?

    While deet-based products make up most of our top-scoring insect repellents, and deet is effective and safe when applied according to the label’s directions, our insect repellent ratings provide a few good alternatives. Several repellents that contain 30 percent oil of lemon eucalyptus (OLE) also earn high marks, for example. For people who prefer a plant-based alternative to deet, OLE offers one reliable option. 

    Here, we explain what oil of lemon eucalyptus is, how well it performs in our tests, and what you need to know about its safety.

    What Is Oil of Lemon Eucalyptus?

    Let’s start with what OLE isn’t: It’s not an essential oil, despite a name that would understandably make you think otherwise. Instead, it’s refined from oil extracted from the Australian plant Corymbia citriodora, also known as lemon-scented gum. (That’s another misleading aspect of the name oil of lemon eucalyptus: Corymbia citriodora used to be considered a member of the Eucalyptus genus, but it isn’t anymore.)

    The main component of oil of lemon eucalyptus that gives it its repellency to bugs is a chemical called p-Menthane-3,8-diol, or PMD. PMD came to the attention of U.S. scientists in the 1990s, after they learned that a Chinese insect repellent, called Quwenling, was performing better than many other plant-based repellents. Quwenling’s main component is PMD.

    How Well Does OLE Work?

    CR tests insect repellents by having volunteers put their repellent-covered arms into cages full of disease-free mosquitoes and seeing how long it takes for them to start biting. Our current ratings include eight products we’ve tested that have 30 percent oil of lemon eucalyptus. Of those, four performed well enough to earn our recommendation—which means they provided at least 5 hours of protection against mosquito bites.

    More on Insect repellents

    That means that after deet, oil of lemon eucalyptus has one of the best track records of success against mosquitoes in our testing, says Chris Regan, who leads CR’s insect repellent testing.

    PMD can also be an active ingredient on its own, without being part of an OLE formulation. We’ve tested one product that lists PMD alone as its active ingredient, a spray that contains 10 percent PMD (about half the concentration of PMD that’s found in 30 percent oil of lemon eucalyptus products). It received only a Fair rating in our tests.

    The labels of the oil of lemon eucalyptus products in our ratings tend to mention only their efficacy against mosquitoes, and CR’s tests evaluate only how long a repellent keeps mosquitoes at bay. 

    Oil of lemon eucalyptus does also have some efficacy against ticks, says Joel Coats, PhD, a distinguished professor emeritus of entomology and toxicology at Iowa State University. Still, “it still doesn’t last as long as people would like,” he says.

    Is Oil of Lemon Eucalyptus Safe?

    The safety of OLE isn’t as well studied as, for instance, deet. But evidence suggests that it poses little risk when used according to the label. For one thing, the EPA classifies oil of lemon eucalyptus as a biopesticide, which means that it’s a naturally occurring substance considered to be a lower risk than more conventional pesticides.

    The main risk of oil of lemon eucalyptus is that it could be harmful to your eyes, so take care to avoid spraying it in such a way that it might get in your eyes. As always, when applying repellent to your face, you should spray it into your hands first and rub it onto your face.

    The other caveat: Oil of lemon eucalyptus shouldn’t be used on young children. “It’s not registered for children under 3 years of age,” says Mustapha Debboun, PhD, a medical and veterinary entomologist and general manager of the Delta Mosquito & Vector Control District in Visalia, Calif. OLE’s safety hasn’t been well studied in this group.

    Oil of Lemon Eucalyptus Insect Repellents to Try

    Here are a few of CR’s recommended products containing 30 percent oil of lemon eucalyptus.

    @consumerreports Replying to @BorgPalace Oil of lemon eucalyptus in bug sprays is a naturally derived active ingredient that can be effective in certain insect repellents. See ratings and reviews at cr.org/insectrepellents 🦟 #bugtok #insects #insectrepellant #insectrepellent ♬ original sound - Consumer Reports

    Catherine Roberts

    As a science journalist, my goal is to empower consumers to make informed decisions about health products, practices, and treatments. I aim to investigate what works, what doesn't, and what may be causing actual harm when it comes to people's health. As a civilian, my passions include science fiction, running, Queens, and my cat. Follow me on Twitter: @catharob