DEET or Lemon Eucalyptus? Pick a Repellent for Your Day

The right repellent depends less on a brand than on the shape of your day. A two hour walk after dinner and a ten hour day on a lake are different problems, and the two best known registered options, DEET and oil of lemon eucalyptus, tend to suit them differently.

Lemon Eucalyptus Essential Oil

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First, which lemon eucalyptus we mean

The "lemon eucalyptus" in a repellent is oil of lemon eucalyptus (OLE), a refined, EPA-registered material, usually listed with its PMD component. It starts with the same tree as our oil, which is why the names get tangled. What we sell is the steam-distilled leaf essential oil, bottled undiluted for diffusers, soaps and candles. CDC says it does not recommend using "pure" oil of lemon eucalyptus as a repellent, and it is not registered with EPA as one, so everything below is about registered OLE and PMD products compared with registered DEET products. For the full explanation, see oil of lemon eucalyptus explained.

What the studies say about staying power

The classic comparison is a 2002 New England Journal of Medicine study with 15 volunteers in a controlled laboratory. DEET products gave complete protection for the longest time, and higher concentrations lasted longer. A formulation with 23.8% DEET had a mean complete protection time of 301.5 minutes, a little over five hours. That study predates today's registered OLE products, so it is a statement about DEET's strength, not a dismissal of OLE.

The picture for OLE and PMD is warmer in later work. A 2006 review by Carroll and Loye describes PMD as a spent product of the distillation of lemon-scented gum leaves and concludes that CDC's endorsement of it was warranted, probably underestimating its value as a DEET alternative. In a 2017 wind-tunnel study, the spray-on products containing DEET and PMD had the highest efficacy among eleven repellents, ahead of products with other ingredients. We would summarize it this way: a registered OLE product is a credible choice for a shorter outing, and DEET is the one with the long record for an all day stretch.

Concentration matters too, whichever you pick. CDC's Yellow Book notes that products with less than 10% active ingredient might offer only limited protection, often one to two hours, that higher concentrations give longer protection regardless of the ingredient, and that DEET's efficacy tends to peak at around 50%. The practical lesson is to read the percentage and the protection time on the label of the exact product in your hand.

Age is the biggest dividing line

CDC's consumer guidance says not to use products containing OLE or PMD on children under 3. EPA's page adds nuance: some OLE labels carry that restriction while certain products with OLE as the sole active ingredient at 30% or less do not, and the Yellow Book mentions the same exception. We would follow the label, and the stricter line if the label is silent, and let a pediatrician advise for any specific child. DEET has no age restriction in the Yellow Book, though labels can add their own wording, and EPA suggests applying any repellent to your own hands first and then to the child, never to a child's hands.

Both types share the same ground rules. Apply to exposed skin and clothing only, skip cuts and irritated skin, keep it away from eyes and mouth, and wash it off when you come indoors. Our post on lemon eucalyptus and kids covers the family angle.

It helps to picture your day before you choose. Think about how long you will be outside, how much you will sweat, who is coming with you and where the water is. A product that fits that picture is the right one, and a few minutes of planning at the kitchen table beats a lot of guessing at the trailhead.

Matching the product to the plan

Your plan	Where we would lean
Full day outdoors, reapplying is a nuisance	A registered DEET product, at the strength the label states
Short evening outside, adults or older children	A registered OLE or PMD product, reapplied on the label's schedule
A child under 3	Ask a pediatrician first, and read the label closely
Travel to an area with serious mosquito-borne illness	See a travel-medicine clinic before you go

This is reasoning from the studies and the labels, and the labels have the final word. Our guides on comparing repellent ingredients and travel mosquito protection pick up where this leaves off.

Habits that help with either one

Whichever product you choose, a few small habits make it easier to use well:

Read the label at home, not on the trail, so you know how much to use and when you may reapply.
Keep the bottle somewhere you will see it on the way out, such as by your keys or in the day pack you always grab.
Put a spare small bottle in the pack for long days.
Make a note on your phone of the time you applied it, so you are not guessing at six in the evening.

Where our oil belongs

Lemon eucalyptus essential oil earns its place on a different shelf: a bright citrus-green top note for a diffuser blend or a hand-poured candle. When the bugs are out, let a registered product do that job and keep the oil for the scent you come home to.