DEET stinks. When I spray myself with Off! before heading out to a summer concert, I always end up coughing and wheezing, a victim of my own chemical warfare—but I also never return home with mosquito bites. The next time I'm at the store, though, I notice all those other options on the shelf, and half the time, I succumb to the allure of "all-natural essential oils" that smell lovely and promise to be just as effective at keeping bugs at bay. But after my next outing to a rooftop bar, I end up lying awake, scratching, wondering whether I just contracted West Nile or Zika.
I go through this dilemma every summer and have come to assume that whether I go with super-effective, DEET-filled bug repellents or gentle, better-for-you-seeming alternatives, I'm just picking my (literal) poison.
But I might be assuming wrong. The scientific and medical communities have looked at this time and again, and their overwhelming conclusion is that DEET is not going to kill us. To the contrary, it is one of the best ways to avoid mosquito- and tick-borne diseases. Short of staying indoors, anyway.
"It's something that has the benefit of being used by hundreds of millions of people across the globe, in different concentrations, over decades and decades," says David Andrews, Ph.D., senior scientist at the nonprofit Environmental Working Group (EWG)."It really has that history of longtime use and very little concern."
Here's the real lowdown on the chemical DEET, otherwise known as N,N-diethyl-meta-toluamide, and other insect repellents that truly work… plus all those that don't.
DEET: Science Vs. Suspicion
First developed in U.S. Army labs in 1946 and made available to the public in 1957, DEET basically works because it smells and tastes bad to insects. In its annual report on insect repellents, EWG lists DEET as a top choice because it is effective at repelling a broad range of species over long periods of time, and it is so widely available and time-tested.
So why are we so suspicious of it? "It gives off a unique scent and also the fact that it has the ability to melt plastics—combined, that makes you think 'chemical,' " Andrews says.
The other reason behind our doubts: reports of seizures caused by brain damage in a handful of children and adults (14 known cases from 1960-1998) and symptoms such as dizziness and insomnia in a study of parks service employees in the Florida Everglades. That's been enough to set off those alarm bells for many, despite the fact that study after study through the decades since those reported cases have shown that such reactions are very rare when the product is used properly.
And while the idea of any toxic reaction to a chemical sounds scary, most doctors believe the evidence that it's fine for most people, especially since the body breaks it down completely within 24 hours of exposure. The Centers for Disease Control and Prevention, the Environmental Protection Agency, and the American Academy of Pediatrics all say DEET is fine for adults and children over two months of age. (EWG and Health Canada say six months.)
"The AAP looks at all the literature and puts out a recommendation based on scientific facts and experts," says Suzan Mazor, a board-certified doctor specializing in toxicology and pediatric emergency medicine at Seattle Children's Hospital. "As long as they're able to continue to do that, we don't need to look at every Facebook article that comes out. I feel comfortable looking at the AAP recommendations and not having to look at the primary data."
Use As Directed
Still, there are some adverse reactions to DEET when you don't follow the application directions, including irritated eyes, nausea (if it's ingested), and rash from extended exposure.
"Don't spray it in your face; put it in your hand instead," Mazor says. "Same thing with cuts or wounds—you don't want to spray it on there. You don't want to put it on the hands of little kids or near their eyes or mouth. Use just enough to go on the exposed skin. Not under clothes. Wash it off when you come back inside."
Despite repeatedly telling us that DEET is safe, experts are also quick to add that no one should be exposed to more of the chemical than absolutely necessary. While the EPA says a 100-percent concentration is fine for adults, the EWG suggests that even adults keep to the 30 percent or less concentration recommended for children.
But wait, if DEET isn't harmful, why do we have to worry about its concentration?
"It just hedges against the tiny bit of concerning information out there," Andrews says. Higher concentration doesn't mean it's more repellent, he explains, just that it lasts longer. So reapplying the lower concentration repellent periodically is preferable to using more than you need.
And even though DEET isn't carcinogenic, I probably shouldn't be inhaling it anymore.
"We definitely recommend not opting for aerosol," says Carla Burns, research analyst and coauthor with Andrews of EWG's 2018 Guide to Bug Repellents. "Lotion, some wipes that are on the market now—those are easy to apply and easy to carry around. If you do use a spray, opt for a pump."
Meet the DEET Alternatives
If that stench still makes you wonder if maybe you're part mosquito, you can opt for a repellent that contains picaridin or IR3535.
-Picaridin came on the market in 2005, which means scientists have had enough years to evaluate its long-term effects, Andrews says. It has no smell and, so far, only minor or moderate cases of reactions to picaridin products have been reported. It's also just as effective as DEET at repelling mosquitoes and ticks.
-IR3535 has been used in Europe for 20 years and hit U.S. shelves in 1999. Aside from being irritating to the eyes, according to EWG, there have being no known adverse reactions to the chemical. In testing, it appears to provide longer protection against ticks than DEET and picaridin. The only possible problem is that it's most commonly found in sunscreens, which EWG doesn't recommend using as a combined product with bug repellent because people need to reapply sunscreen much more often than they do repellent.
-Oil of lemon eucalyptus sounds like a refreshing option, but don't go thinking it's "all-natural."
"If you buy an essential oil of eucalyptus, it won't provide the same repellency," Andrews warns. The variation of the oil used in most products is processed to increase the concentration of the chemical para-menthane-3,8-diol, or PMD. As such, it has been subject to EPA safety and efficacy approval, unlike essential oils. Products that contain a combination of the oil and synthesized PMD have been shown to be as effective as lower concentrations of DEET. Not enough testing has been done to determine whether this product is safe for children under 3.
All the Other Botanicals
While some essential oils, such as citronella and geranium, have been shown to repel insects, they don't last nearly as long as the chemicals above.
"In situations where there are not very many biting insects and you're not concerned with mosquito-borne diseases, you can give it a try, but we really don't think they're first choices," Andrews says.
There are two real problems with botanical products: 1) They're not regulated, so you don't know for sure whether what you're buying has been tested for safety and efficacy, and you don't know how much of the active ingredient you're getting. 2) They may cause an allergic reaction.
"Essential oils are famous in the dermatology community for causing rashes," Mazor says. Still, she understands the inclination to avoid standard insect repellents. "People are nervous about chemicals versus 'natural products.' I mean those words in quotes because a lot of chemicals are natural, and natural things do have chemicals."
If what you're really looking for is a way to put fewer questionable ingredients on your skin while also not contracting Lyme disease, West Nile, or any of the diseases that nature's little vampires are carrying around, you have other options. And no, we're not talking about candles or bracelets, which are also problematic, according to EWG. (Burning citronella candles are an inhalation hazard, while the wristbands have been shown to be ineffective).
Instead, you can solve this problem with fashion: You can buy clothing pretreated with the insecticide permethrin, which is very effective against ticks (it's also a neurotoxin, though found to be safe in pretreated clothing). Or you can cover up and hope the insects aren't desperate enough to bite you through your pants.
"Shirts and pants, when possible, can go a long way," Andrews says.
But if, like me, you want to feel those summer breezes while you can—it's time to hold your nose and lotion up.