DEET, Picaridin, OLE and More: Which Repellent Fits?

There are six active ingredients on CDC's list of repellents to look for, and the internet will tell you one of them is "best." We would rather tell you how they differ so you can pick the one that suits your day. Duration, feel, age rules and how many products you can actually find all play a part.

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The six, in plain terms

CDC lists DEET, picaridin, IR3535, oil of lemon eucalyptus (OLE), para-menthane-diol (PMD) and 2-undecanone as the active ingredients in EPA-registered repellents. CDC describes OLE and 2-undecanone as plant-derived. EPA's ingredient page shows how uneven the shelf is: more than 500 DEET products, about 40 with picaridin, about 45 with IR3535, six each for OLE and PMD, and one for 2-undecanone. If you want a plant-derived ingredient, you are choosing among very few bottles, which is a good reason to read them carefully.

Walk down the repellent aisle with that list in your pocket and the front of the bottle matters less than you would think. Flip it over and find the active ingredient in the small print on the back. Names like "clean" or "outdoorsy" tell you about the marketing, and the active ingredient and its percentage tell you about the product.

What the studies say about duration

The famous head-to-head is a 2002 study in the New England Journal of Medicine. Fifteen volunteers tested a wide range of products in a controlled laboratory. DEET-based products gave the longest complete protection, with a 23.8% DEET formulation averaging 301.5 minutes. A soybean-oil repellent averaged 94.6 minutes, the IR3535 product 22.9 minutes, and the other botanical products under 20 minutes. The wristbands gave none. It is a landmark, but it is also more than twenty years old and it did not test today's registered OLE products, so we treat it as the origin of the "DEET lasts longest" idea and not as a verdict on every product now.

A 2015 laboratory study of eight commercial products against two Aedes mosquito species found DEET products held repellency longest, PMD products gave comparable results for shorter periods, and some citronella or geraniol products showed no significant repellency. A 2006 review of PMD argued that its efficacy is DEET-like against several mosquito genera. Taken together, we read them this way: PMD can come close to DEET, but usually for fewer hours, and an unregistered plant product is a different animal altogether.

What that means for choosing

For a long day with mosquitoes the main worry, DEET or picaridin at the label's stated strength has the strongest case in these comparisons. CDC adds that DEET efficacy tends to peak around 50%, so a higher number is not automatically better, and that products under 10% active ingredient might give only 1 to 2 hours.

For a short outing, an adult, and a preference for plant-derived, a registered OLE or PMD product is a reasonable choice. Plan on reapplying as the label directs, and keep in mind that CDC says not to use OLE or PMD products on children under 3. Our look at what the 30% means explains the numbers on those labels.

For ticks, pick a product whose label lists ticks, and treat your clothing with permethrin as a second layer, as we explain in lemon eucalyptus versus permethrin.

For travel to places where mosquito-borne illness is a real concern, a travel-medicine clinic should make the call. A comparison article is the wrong tool for that decision.

Natural is not the dividing line

Many ingredient comparisons sort things into natural and synthetic and assume that predicts the outcome. The studies above do not support it. OLE and PMD sit close to DEET in some tests, while unregistered botanical products did far worse. What predicts a good result is whether a product is EPA-registered for the claim it makes, and it is the same point CDC makes when it says it does not know the effectiveness of non-registered repellents, including some natural ones.

Where our oil sits

We sell lemon eucalyptus essential oil for scent and craft, and it is none of the six. CDC does not recommend using undiluted oil of lemon eucalyptus as a repellent, since it has not undergone validated testing and is not EPA-registered. The refined, PMD-enriched ingredient in registered products is a different material from the oil in our bottles; our comparison of OLE and the essential oil shows the split in detail. We do not sell repellents of any kind, and we would rather say that clearly than blur it.

Feel, smell and the things nobody lists

Comparison charts leave out something real: whether you will like wearing the stuff. Some people hate a greasy lotion, some cannot stand a heavy mist, and some pick the bottle that smells least like a gas station. If you dislike a product, it stays in the glovebox, and a repellent in the glovebox does nothing for you.

If you are unsure, a small size is a cheap way to find out what you will really reach for before you commit to a big bottle.

Picking one off the shelf

Find the EPA registration number and the active ingredient with its percentage. Look for the protection time, which EPA allows manufacturers to show in an optional graphic. Check the age statement. Apply sunscreen first and repellent second, and follow the reapplication rule printed on the label. EPA notes that protection times vary because of differences in testing conditions, so the label for the exact product beats any general ranking, including this one.