Oil of lemon eucalyptus by any other name would smell as sweet. And be less confusing.

We’ve all seen the headlines.
”CDC confirms oil of lemon eucalyptus as effective as DEET.”

Oh, what a tangled web this weaved! I first noticed these circulating around 3 years ago when I did my first myth busting post on this topic in my Not Your Average Oiler Facebook group, but upon closer inspection these headlines may have been around as early as 2011, and the product has been EPA registered as early as 2000.

The issue is that “oil of lemon eucalyptus” or OLE is not actually lemon eucalyptus essential oil.

Did your head just explode? I KNOW. Why on God’s green Earth would you come up with a name so similar to what folks use for the EO? The confusion is understandable. Here’s the deal.

Lemon eucalyptus essential oil is steam distilled from a delightful tree native to Australia (though the EO may be sourced from other locations such as India, China, and Madagascar), eucalyptus citriodora or corymbia citriodora (there isn’t even consensus on the botanical name… this doesn’t bode well for us.) It’s often called “lemon-scented gum,” “lemon-scented iron gum,” and “spotted gum” - the last of which is just charming, don’t you think?

The EO has primary constituents of citronellal, citronellol, and isopulegol with varying other compounds depending on where the botanical was sourced. The citronellal is what gives it some heft in bug-away blends; for comparison, lemon eucalyptus EO has 66-86% citronellal while citronella is more likely in the 30-40% range for citronellal content. Although this compound is useful in bug-away blends, due to the volatility of EOs you typically need to reapply any preparations quite regularly (think hourly) to maintain effectiveness.

Now, on to OLE which is NOT, as noted, the same as lemon eucalyptus EO.

The steam distilled lemon eucalyptus EO is further refined in a process that converts some of that generous citronellal content into cis- and trans- isomers of p-menthane-3,8 diol (PMD). This conversion can occur naturally in the plant as the leaves age, but the amount of PMD present without the additional refining process is very small, think <2%. The refined product that converted citronellal into PMD while still containing some of the other EO constituents is what is known as OLE. It’s like the EO on steroids. (Initially the PMD was discovered in the waste hydrous portion of the distillate after hydro-distillation, but now it is bio-synthesized through the refining process as described above.)

This refined product has a trade name of Citriodiol, but is known by other names varying by region. We have Oil of Lemon Eucalyptus/OLE in the states (…thanks, said NO ONE), PMD Rich Botanic Oil in Europe, also Eucalyptus Citriodora oil, hydrated, cyclized in Europe as of 2016 to comply with European Biocidal Products Regulation in the EU, and Extract of Lemon Eucalyptus sometimes in Australia. What, no one wanted to jump on the bandwagon with Spotted Gum Juice? Because I think we need ANOTHER DAMN NAME.

So technically, OLE is the refined/biosynthesized product made from the EO that contains high levels of PMD. I have in the past, as have many other resources, equated OLE with PMD as being the same thing. Although they are technically not the same - as noted the OLE contains high levels of PMD - you will still often see the terms used interchangeably, so just be prepared for that. When you search for products containing these active ingredients, you could search for OLE OR PMD. Both will have the high levels of PMD, and that’s the real money maker for long-lasting efficacy and comparable prowess to DEET.

How much PMD do we need? Citriodiol/OLE/spotted gum juice (hee) should have 64% PMD, and then in a finished product formulation the total PMD content should be around 20-30% or more to compare to DEET.

It is the OLE and PMD that are recognized by the CDC as effective as DEET. They are the ones recommended by the EPA as effective and registered insect repellents. These are the bad boys that can hang with you and keep those skeeters away for up to 8 hours.

And once more for the cheap seats in the back?

They are NOT the same as the unrefined lemon eucalyptus EO, which may keep bugs away for an hour or so and then need reapplication (properly diluted, of course. You know how we roll).

The unrefined EO that is not equivalent to DEET.

The unrefined EO with a painfully similar name to OLE but yet is an entirely different product because some people just like to watch the world burn.

Now, I get the confusion. CLEARLY. What a hot mess. But I do take issue with professionals in the field of aromatherapy who ignore the truth of this matter when educated about this confusion and presented with every bit of evidence confirming the unrefined EO is not as effective as DEET/that the actual OLE/PMD is an entirely separate product. Despite this, they continue telling their followers to go out and buy lemon eucalyptus EO, make their own bug spray, and be as perfectly protected as they would be had they marinated in DEET. That’s a hard no, and it disappoints me that some people with a lot of reach refuse to recognize new research as it becomes available and adjust their teachings accordingly.

Be vigilant when sourcing your information, because having an aromatherapy certification does not always equal exercising best practice within that field.

You can search for products by ingredient on the EPA website here.

You can read about various other botanicals (including OLE) and their relative efficacy against bugs here.

You can read the EPA’s fact sheet on PMD here.

You can read the registration eligibility document for PMD (with all relevant animal testing) here.

You can read another post about this topic from Sue Pace (RN and aromatherapist) here.

You can read another post about this topic from Dr. Shannon Becker (aromatherapist with advanced training in aromatic medicine, PhD) on her page here.

You can read a study on the efficacy of OLE, which fantastically calls it LEO (are you drinking yet? You should be. Holy hell.) or Mosi-Guard here.
Mosi-Guard is an Australian product using Citriodiol, the refined product trade name for OLE we’ve already talked about above. You can read about it here. In other words, **not the same as the unrefined EO**

You can read about Citriodiol here.