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Permethrin

Also called permethrin clothing treatment, permethrin-treated clothing

What is permethrin?

Permethrin is an insecticide you spray on clothing, boots and gear, never on skin, to protect against ticks and mosquitoes. The CDC recommends 0.5 percent permethrin products for tick prevention. A treatment lasts through several washes, and it is dangerous to cats and fish while wet.

Permethrin at a glance

Strength
0.5 percent
What the CDC recommends
Applied to
Clothing and gear
Never skin
Lasts
About 6 washes
Sawyer's figure for a spray-on coat
Chemical family
Pyrethroid

How is permethrin different from bug spray?

A skin repellent like DEET or picaridin keeps bugs from wanting to bite. Permethrin is an insecticide in the pyrethroid family, synthetic chemicals that act like natural extracts from the chrysanthemum flower. It acts on an insect's nervous system, so it works on a tick crawling across treated fabric instead of only putting it off.

That is why it goes on clothing and gear. The CDC advises treating boots, clothing and camping gear with 0.5 percent permethrin, and never using permethrin products directly on skin.

How long does permethrin last on clothes?

A spray-on treatment lasts through washing. The CDC says treated items stay protective through several washings, and Sawyer, a widely used consumer brand, says one treatment lasts six weeks or six washes. The EPA advises washing treated clothing separately from untreated clothing.

Clothing can also be treated at the factory, and permethrin is the only repellent currently used for that. The EPA's 2009 assessment found factory-treated clothing unlikely to pose any significant hazard to the people wearing it.

Is permethrin safe around pets and water?

Keep it away from cats until it is completely dry. The National Pesticide Information Center says cats are more sensitive to permethrin than dogs or people, because their bodies take a long time to break it down.

It is also highly toxic to fish and other aquatic animals, so treat gear well away from streams and lakes and never rinse the sprayer into water.

What this means when you're choosing

  • 0.5 percent permethrin on the label
  • A trigger spray for even coverage on pants and socks
  • Enough volume to treat each outfit you hike in
  • Factory-treated clothing if you would rather not spray

The common mistake

Wearing it or spraying it wet

Permethrin needs to dry completely on the fabric before anyone puts it on, and it should never go on skin. Treat clothes outdoors, hang them to dry for at least two hours (Sawyer says four in humid weather), and keep cats away until they are dry.

Common questions

Can you put permethrin on your skin?

Not the clothing treatment. The CDC says not to use permethrin products directly on skin. Use a skin repellent such as picaridin or DEET on exposed skin and permethrin on the clothes over it.

What should you treat with permethrin for hiking?

Start with what ticks reach first: socks, boots, pant legs and gaiters. Then the shirt and hat. The CDC also lists tents and other camping gear as things you can treat.

Where this is defined

Where this comes up

Guides on Tom's Hiking where permethrin changes which product is right for you.

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