What really works against bug bites


What really works against bug bites

Consumer Reports reveals new, safer options to keep mosquitoes and ticks at bay

Published: May 13, 2015 06:00 AM

Some of the insect repellents we tested.
Photo: Travis Rathbone

Would you rather be eaten alive by mosquitoes and ticks that can carry debilitating—and even deadly—diseases or douse yourself in harmful repellents full of potentially dangerous chemicals? Almost three-quarters of Americans say they worry more about insect-carried diseases, such as West Nile and Lyme as well as newer threats like chikungunya and Powassan, according to a recent Consumer Reports survey of 2,011 U.S. adults.

Here’s the real dilemma, though: Most people also say that safety is key when they choose a repellent, but only about a third think the products now on the market are safe for adults. Even fewer—23 percent—think the repellents are safe for kids.

If you’re conflicted about what to do, we have good news: For the first time ever in Consumer Reports’ tests of insect repellents, new, safer products—made with milder, plantlike chemicals—were the most effective. (Check our insect repellent Ratings and buying guide.) The top scorers outperformed products that contained deet, a chemical that did best in our previous Ratings but can cause serious side effects.

The active ingredients in the top repellents are chemically synthesized compounds that are similar to or come from natural ingredients. The secret sauce in the best-scoring Sawyer product is picaridin; in the Repel it’s oil of lemon eucalyptus. They are not side-effect-free, but “those problems are much less severe than deet,” says Urvashi Rangan, Ph.D., executive director of Consumer Reports’ Food Safety and Sustainability Center. “Still, all repellents should be used sparingly and only for the time you need them—especially on children and older people.”

That’s why an effective bug-avoidance strategy requires a full arsenal. Our new tests identify non-chemical approaches that offer some relief (setting up a fan on your back patio, for example) and those that don’t help much if at all (think citronella candles, wristbands, and “all-natural” products with geraniol, lemongrass, and rosemary oils).

What bugs a bug most?

To find effective spray-on repellents, we went to an outside lab and tested 15 pump sprays and aerosols. The products contained deet, oil of lemon eucalyptus, picaridin, a chemical called IR3535, and products made with natural plant oils.

Our brave testers had a different repellent applied to each of their forearms and, 30 minutes later, reached into an 8-cubic-foot cage containing 200 disease-free, female mosquitoes in need of a blood meal to lay their eggs. We used culex mosquitoes (the kind that transmit West Nile and are most active between dusk and dawn) and aedes (a variety that likes to feed on humans, is active all day long, and carries chikungunya). Our experts watched and recorded bites every hour.

A repellent failed if a tester was bitten two or more times in one 5-minute session, or once in two consecutive sessions. For ticks, we marked each tester’s bare arms with three lines, then released, one at a time, five disease-free deer ticks to crawl on them. The repellent failed if two ticks crossed into the treated area.

The top-performing products contained 20 percent picaridin and 30 percent oil of lemon eucalyptus. They kept mosquitoes and ticks away for at least 7 hours. Two deet products also earned at least Very Good scores, and the repellent that was 15 percent deet outperformed the 25 percent deet product, possibly because of its inactive ingredients. The IR3535 products didn’t make our list of top sprays. Some of the plant-oil products couldn’t ward off the aedes mosquitoes for even half an hour.

The scoop on deet and its alternatives

Deet (N, N-diethyl-meta-toluamide) has been the go-to insect repellent since it was introduced in the 1950s. But consumers are still confused by it: 64 percent of people we surveyed admit that they don’t know how much deet a repellent should contain for it to be considered safe. And balancing safety and effectiveness is tricky. Products with 15 percent or more deet do work, though concentrations above 30 percent are no better, past tests have found. And deet, especially in high concentrations, can cause rashes, disorientation, and seizures. That’s why we say you should avoid repellents with more than 30 percent deet and not use it at all on babies younger than 2 months. But go too low—such as 7 percent deet—and it won’t stop bites for long.

Picaridin and oil of lemon eucalyptus—two repellents introduced in the last decade—make good alternatives to deet. Here’s why.

They work. The repellents we tested that contain 20 percent picaridin and 30 percent oil of lemon eucalyptus (p-Menthane-3,8-diol) warded off mosquitoes for at least 7 hours and kept deer ticks away for at least 6 hours. But the concentration is important: A spray that contained just 5 percent picaridin performed worse than the 7 percent deet product we tested.

They’re safer. Picaridin is made to resemble the compound piperine, which occurs naturally in black pepper plants. Oil of lemon eucalyptus comes from the gum eucalyptus tree. Both have less serious side effects than deet has. Oil of lemon eucalyptus can cause temporary eye injury. The Food and Drug Administration says it should not be used on children under age 3. Of the two, picaridin is a better choice for kids, although it can cause some irritation of skin, eyes, and lungs.

How to safely use insect repellents

Proper use is essential, even with safer products. That means:

• Apply repellents only to exposed skin or clothing (as directed on the product label). Never put it on under clothing. Use just enough to cover and only for as long as needed; heavy doses don’t work better.

• Don’t apply repellents over cuts, wounds, or irritated skin.

• When applying to your face, spray first on your hands, then rub in, avoiding your eyes and mouth, and using sparingly around ears.

• Don’t let young children apply. Instead, put it on your own hands, then rub it on. Limit use on children’s hands, because they often put their hands in their eyes and mouths.

• Don’t use near food, and wash hands after application and before eating or drinking.

• At the end of the day, wash treated skin with soap and water, and wash treated clothing in a separate wash before wearing again.

The danger in the bite

Mosquito-borne diseases

West Nile was reported in 47 states last year and killed 85 people in the U.S. Chikungunya isn’t as widespread—yet—or as deadly. Of the almost 2,500 cases reported in the continental U.S. since January 2014, there were no deaths, and only 11 cases were from bites received in the continental U.S. (all in Florida). The rest were brought back from the Caribbean, Asia, or Africa. But experts worry that chikungunya may be prone to large outbreaks in urban settings. The mosquitoes that carry it bite all day long. Plus, roughly 70 to 90 percent of infected people develop symptoms, compared with 20 percent of those infected with West Nile.

What to do. See a doctor if you develop signs of either disease: fever, headache, and body aches for West Nile; and fever and joint pain for chikungunya. Both are viral, so antibiotics won’t help. But over-the-counter pain relievers can ease symptoms.

Tick-borne diseases

Lyme disease affects about 300,000 people each year, mostly in the Northeast and Upper Midwest. But that geographic reach is expanding, and doctors in new areas may be less familiar with the disease. Other tick-related diseases include Rocky Mountain spotted fever, most often in North Carolina, Oklahoma, Arkansas, Tennessee, and Missouri; babesiosis, in the Northeast and Upper Midwest; ehrlichiosis, in the Midwest and South; and an emerging virus, Powassan, mainly in the Northeast and Great Lakes region.

What to do. See a doctor if you develop a bull’s-eye rash accompanied by flu-like symptoms, which indicates Lyme. Prompt treatment can stop the infection and prevent more serious complications, such as joint pain and facial paralysis (Lyme disease); heart, joint, or kidney failure (Rocky Mountain spotted fever); blood clots and bleeding (babesiosis); difficulty breathing or bleeding disorders (ehrlichiosis); and neurological problems (Powassan).

Editor's Note:

This article also appeared in the July 2015 issue of Consumer Reports magazine.

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