A tick rests on a person's hand.

Shirts, pants, hats, and other clothing treated with the insecticide known as permethrin have been touted for 15 years as a way to prevent the tick bites that can lead to Lyme disease, Rocky Mountain spotted fever, and more. But research hadn’t proved that permethrin-treated clothing items are actually effective tick-stoppers.

Tick-borne illnesses, especially Lyme disease, are on the rise and occurring in an increasingly wide area, according to a recent report from the Centers for Disease Control and Prevention, making it more important than ever to protect against tick bites. 

More on Ticks

Now, a new study by CDC researchers has found that just a minute or two of contact with permethrin-treated clothing caused ticks to become incapacitated or fall off fabric.

The research examined a variety of permethrin-treated clothing types and fabrics. It revealed that the items can be toxic to several species of ticks and at different stages in their life cycles, potentially keeping them from getting beneath clothing and staying next to skin long enough to bite.

While the CDC research sounds promising, it’s still unclear whether the permethrin-embedded apparel actually prevents bites, says James Dickerson, Ph.D., Consumer Reports’ chief scientific officer.

"The CDC’s study did not test any items while they were being worn, so it doesn’t show conclusively how well the clothes might keep ticks from biting you," Dickerson says.

Consumer Reports has tested the effectiveness of permethrin-treated clothing but only for its ability to stop the bites of mosquitoes, not ticks.

In our tests, permethrin-treated shirts from L.L.Bean and ExOfficio treated with 0.52 percent permethrin—the industry standard—did kill or incapacitate mosquitoes. But in some cases the mosquitoes were still able to bite wearers. (For more on this testing, see our report.)

Here’s what you need to know about this new research, and what’s most effective at preventing tick bites.

What the Scientists Found

The CDC team placed ticks on swatches of cloth cut from different articles of permethrin-treated clothing manufactured by the company Insect Shield. (Insect Shield manufactures permethrin-treated clothing that’s sold by other companies, such as Orvis and ExOfficio.)

Some ticks were collected from the wild, while others were lab-raised, allowing researchers to see whether one type reacted differently to the insecticide.

For several of the tests they used blacklegged tick nymphs (babies), which are the main spreaders of Lyme disease. For other tests they also used lone star tick nymphs as well as adult blacklegged ticks, lone star ticks, and American dog ticks. All of these can also spread disease.

Researchers found some small differences. For example, adult ticks, especially lone star and American dog ticks, withstood the effects of contact with the clothing longer than the nymphs did. But the majority of the ticks exposed to the insecticide-infused fabric were unable to move normally after a few minutes. Some simply slid off the swatches.

That’s important because if ticks fall off your clothing or can’t move, they can’t reach your skin and bite you, says study author Lars Eisen, Ph.D., research entomologist in the division of vector-borne diseases at the CDC. 

Should You Try Permethrin Clothing?

Permethrin is sometimes referred to as a repellent—which keeps bugs from landing on you—but it functions as an insecticide, which means it poisons insects.

To determine whether permethrin-infused clothing actually stops tick bites, a larger study is needed in which people wear regular or treated clothing and go about their normal outdoor activities, says Eisen of the CDC. “We do not have that study yet,” he notes.

Still, "we know that permethrin-treated clothing is toxic to ticks," he says. "So we are assuming that if you are adequately covered by permethrin-treated clothing, there’s no reason it should not be protective.”

The Environmental Protection Agency says that the amount of permethrin allowed in treated clothing and other consumer products is safe. (It’s also in some insect sprays, which are meant to be used on clothing before you put it on, as well as in products like some head lice treatments.)

It is not recommended, however, that permethrin be sprayed directly on skin, and the EPA considers it a likely human carcinogen when ingested.

The CDC includes permethrin-treated clothing in its recommendations for preventing tick bites along with other measures, like those below.

Consumer Reports' experts are more cautious. Dickerson says that while there’s likely little harm in wearing permethrin-treated clothing, using a bug repellent, rather than an insecticide, should be your first line of defense. 

“Repellent is the best way to ensure that bugs don’t have an opportunity to bite you,” he says.

Consumer Reports tests insect repellents each year for their effectiveness against mosquitoes. Our experts say that the repellents that work best against mosquitoes are also the ones that are likely to be most effective against ticks, too.

Most of our recommended brands contain deet at concentrations of 15 to 30 percent; a few contain 20 percent picaridin or 30 percent oil of lemon eucalyptus. Members can check our ratings here to see our top performers.

Protect Yourself from Tick Bites

Before entering an area that may have ticks, such as woods or tall grass, put on a long-sleeved shirt, long pants, and closed-toed shoes, and tuck your pants into your socks.

Apply insect repellent to all your exposed skin after you've put on sunscreen, but not under your clothes.

For added protection, you can spray repellent onto your clothing before you put it on. (Let the clothing dry before putting it on, launder these items in a separate wash before wearing them again, and note that some repellents may stain clothing and damage leather and vinyl).

And if you do want to use permethrin-treated clothing, you can buy it pretreated with the insecticide or spray it onto clothing yourself. Just be sure to spray clothes while they’re hanging up (not while wearing them), and never apply permethrin directly to your skin.

To reduce the number of ticks around your home, keep your grass mowed (find our lawn mower ratings here) and remove leaves and debris, because ticks like shade and tall grass.

Finally, be sure to check yourself and your pets for ticks at the end of each day that you’re outside.

The Lowdown on Insect Repellents

Bug bites are not only annoying, they can also transmit diseases. On the 'Consumer 101' TV show, host Jack Rico goes inside Consumer Reports' labs to find out how CR tests insect repellents to make sure you are getting the most protection.