Permethrin is a pesticide that you spray on clothing to kill black flies, ticks, and mosquitoes but has no harmful side effects on humans if used properly. It is the active ingredient used in the Insect Repellent Clothing sold by Outdoor Research Ex Officio, Sea-to-Summit, Royal Robbins, Craghoppers, and others, which kills bugs when they land on your clothing. Permethrin was developed by the U.S. military to protect soldiers from insects in the jungle and is still in use today.
If you want to treat clothing or gear that you already own, you can buy Sawyer Permethrin Spray in liquid form and spray it on your own clothes to the same effect. This self-applied form lasts for 6 washings. I’ve been using it on my hiking pants, shirts, hats, gloves, gaiters, and socks, for well over a decade and found it safe and effective to use.
A big bottle of Sawyer Permethrin comes with a spray adapter and will cover 5 complete sets of clothing, including shirts, pants, and socks. You’ll want to read the directions carefully before applying it, but it’s not difficult to do. You need to spray it on the clothes you plan to wear hiking or for any outdoor activity in a windless but well-ventilated place like a garage. Let them dry for a few hours and you’re all set.
I spray Permethrin on the clothes that I wear for tick hiking in New Hampshire and Vermont, including long-sleeve shirts, convertible hiking pants, gaiters, and hiking socks. When you spray the Permethrin on, you want to position the sprayer 6 to 8 inches away from the clothing you plan to treat. Pay particular attention to the cuffs of long pants and shirt sleeves where ticks will try to attack you. It’s also a good idea to spray it on your hat or to buy one that’s already been treated with Permethrin like the Outdoor Research Bugout Brim Hat.
Sawyer’s Permethrin Spray (24 oz) is pre-mixed to the correct concentration so you can apply it to clothing without any preparation.
I can attest to the effectiveness of Permethrin Spray, particularly against mosquitos and ticks. I rarely ever get bitten as long as I wear a long-sleeved permethrin-treated shirt and pants when I go hiking in the forest. I love having the sun on my arms and legs as much as the next guy, but I’d rather cover up than catch Lyme disease, which the CDC believes is now 10 times more prevalent than previously reported.
More about Permethrin
As a treatment for clothing, Permethrin clothing insect repellent does not harm fabrics and is odorless after it dries. Use Permethrin on clothing by itself or with skin-applied repellents to create the ultimate protective, armor-like insect barrier. Permethrin treatments on clothing are non-toxic to humans and are registered for use by the U.S. EPA.
The active ingredient, Permethrin, is a synthetic molecule similar to those found in natural pyrethrum, which is taken from the chrysanthemum flower. Not only does this product repel insects, but will actually kill ticks, mosquitoes, chiggers, mites, and more than 55 other kinds of insects.
Permethrin insect repellents are for use with clothing, tents, and other gear. During the drying process, it tightly bonds with the fibers of the treated garment. It will not stain or damage clothing, fabrics, plastics, finished surfaces, or any of your outdoor gear.
Permethrin is a contact insecticide, meaning that kills ticks or other insects when it comes in contact with them. It’s also used in hair shampoos for head lice. When applied to clothing the Permethrin binds to the fabric eliminating the risk of over-exposure to the skin. As a clothing, tent, chair, or sleeping bag application, Permethrin is very effective at keeping ticks from attaching to you and in reducing the mosquito population in your camping area. While ticks usually find you at the ankle level (be sure to treat the socks and pants) they can also climb bushes and find you at a higher level so be sure to treat your shirt as well if you are around bushes and concerned about ticks.
Sweating and exposure to water do not significantly deteriorate the application. It is primarily the agitation of a washing machine, which deteriorates the Permethrin application as it knocks the molecules loose from the fabric. For best results, Sawyer recommends hand washing and air-drying. When using a conventional washer and drier, use the gentle wash and dry cycles. Loss due to the drier is limited compared to the detergent and washer agitation. Dry cleaning removes the Permethrin from the fabric.
Permethrin Spray can last up to six weeks through six weekly washings. All treatments are non-staining and not greasy. Always follow the directions for use on the package label. Factory pre-treated Permethrin clothing, however, lasts for 70 washings and is far more convenient if you don’t want to spray your own clothing.
Updated April 2023