Permethrin-Treated Clothing: How Often to Re-Treat, How Long It Lasts, and Why It Never Goes on Skin
Short answer: How often you re-treat permethrin clothing depends on the label: one EPA-accepted 0.5 percent label says a treatment lasts two weeks, another says six weeks or the sixth laundering. One factory-treated apparel label, Insect Shield, EPA Reg. No. 74843-2, is printed for 70, 50 or 25 washings. Permethrin goes on clothing and gear, never on skin; the CDC says do not use permethrin products directly on skin.
How often do you need to re-apply permethrin to clothes?
Every two weeks on one EPA-accepted label, every six weeks or after the sixth laundering on another. The label on the bottle decides, and two 0.5 percent labels on file with the EPA give different numbers.
The label for 0.5% Permethrin Aerosol Spray, EPA Reg. No. 71-1, says one clothing treatment lasts two weeks. It says the active ingredient binds to the fabric for residual protection lasting a minimum of two weeks, through several machine washings. Its limits are printed in capitals: do not retreat clothing more than once every two weeks, and launder clothing at least once before retreating.
The label for CIC Residual Insecticide No. 1, EPA Reg. No. 50404-3, is written for six week protection, 42 days, against ticks, chiggers, mites and mosquitoes. It says protection lasts a minimum of six weeks through several machine washings, and that clothing should be retreated after six weeks or after the sixth laundering to maintain adequate protection. It also tells you not to exceed the recommended spraying times.
Which schedule is yours comes down to the bottle you bought. The CDC's rule covers both: read the product label to find out how long protection will last, then re-treat on that clock.
How long do you let permethrin dry before wearing?
At least two hours, or four hours under humid conditions. Both EPA-accepted 0.5 percent labels give that figure. The label for EPA Reg. No. 71-1 says to hang the treated clothing and allow it to dry for at least two hours, four under humid conditions, before wearing. The label for EPA Reg. No. 50404-3 puts the same numbers next to its spraying directions: treat the outer surfaces of each outfit, front and back, for 30 seconds on each side, then allow at least two hours to dry, or four hours in humid conditions.
The 50404-3 label also carries an alternate set of directions that end with untying the garments and hanging them outdoors. Those directions say to hang the garments outdoors until dry, approximately two to three hours, and that when dry the garments are ready to wear.
NPIC's instruction is about the fabric rather than the clock: hang treated fabrics outdoors and allow them to dry completely before wearing them. NPIC also says to apply the products outdoors, in well ventilated areas protected from wind. Treat the label's hours as the minimum and completely dry as the test.
What is permethrin?
The National Pesticide Information Center describes permethrin as an insecticide in the pyrethroid family, and pyrethroids as synthetic chemicals that act like natural extracts from the chrysanthemum flower. It was first registered with the U.S. Environmental Protection Agency in 1979 and re-registered in 2006, and NPIC counts more than 1,400 registered products containing it.
The EPA is more technical: a broad spectrum, non-systemic, synthetic pyrethroid insecticide that targets adults and larvae of many species of biting, chewing, scaling, soil and flying invertebrates. And when used to pre-treat clothing, it is an insect repellent.
Can you put permethrin on your skin?
No. Three independent sources say so. The CDC says do not use permethrin products directly on skin, and its Yellow Book says permethrin should never be applied to the skin but only to clothing, mosquito nets or other fabrics as directed on the product label. NPIC says permethrin treatments are only intended for use on fabrics and should not be applied directly to the skin or other items. The EPA-accepted labels are the bluntest: the label for EPA Reg. No. 71-1 calls itself a clothing treatment only and says do not apply to skin, and the label for EPA Reg. No. 50404-3 says the product must not be applied to clothing while it is being worn, and that under no circumstances should bare skin or clothing on the body be treated.
The reason is not mysterious. NPIC notes that when people get permethrin on their skin they may have irritation or tingling, burning and itching at that spot, and in the eyes it can cause redness, pain or burning. Wearing the treated fabric is a different exposure. NPIC says permethrin applied properly binds tightly to fabrics, with little loss during washing and minimal transfer to skin, and the EPA says the amount allowed in clothing is very low, that human exposure from wearing factory-treated clothing is also low, and that available data show permethrin is poorly absorbed through the skin.
The practical consequence: exposed skin needs its own product. The factory-treated apparel hang tag says, in capitals, to protect exposed skin with an insect repellent registered for direct application to skin, and the 0.5 percent clothing label says protection from mosquitoes can be further enhanced by applying a repellent to face, hands and other exposed areas of the body. Which one is its own question; we compare picaridin and DEET in picaridin versus DEET.
How does treated fabric actually stop a tick or a mosquito?
By contact. NPIC is blunt about it: "Permethrin is not an insect repellent, but kills insects on contact. It is sometimes used to treat fabrics." An insect has to touch the treated item to be harmed or killed. What follows, per NPIC, is an attack on the insect nervous system, causing muscle spasms, paralysis and death. Permethrin is more toxic to insects than to people and dogs, because insects cannot break it down as quickly.
The CDC frames it as both effects at once. Its Yellow Book calls permethrin a highly effective insecticide, an acaricide, meaning a pesticide lethal to ticks and mites, and a repellent, and says that at 0.5 percent, permethrin-treated clothing repels and kills the ticks, chiggers and mosquitoes that meet it, along with other biting and nuisance arthropods.
Contact creates a hard boundary. The EPA states that when you wear permethrin factory-treated clothing, only the skin surface covered by that clothing is protected from the pests listed on the label, and that other exposed parts of the body should be treated with an insect repellent labeled for use on human skin. Treated pants do nothing for your forearms. The 0.5 percent label tells you to pay particular attention to socks, trouser cuffs and shirt cuffs, and to wear pant cuffs inside socks or footwear for full protection against ticks and chiggers.
Do permethrin treated socks and boots actually work?
Yes, and footwear is the standout. NPIC says permethrin is not an insect repellent but kills insects on contact, so an insect has to touch the treated item, and applied properly it binds tightly to fabric. NPIC says permethrin is the only pesticide with an EPA registration for treating fabrics; the CDC says it can treat boots, clothing and camping gear.
The hard number is from Miller and colleagues, Journal of Medical Entomology, March 2011, volume 48, issue 2. Researchers placed pathogen-free nymphal Ixodes scapularis on the left shoe, right leg and left arm of 15 volunteers in outfits untreated or treated with permethrin, commercially or with a do-at-home kit, and recorded attachment 2.5 hours later. Subjects in permethrin-treated sneakers and socks were 73.6 times less likely to have a tick bite than subjects in untreated footwear. Whole treated outfits took 3.36 times fewer bites; treated shorts and T-shirts made a bite 4.74 and 2.17 times less likely where they covered. Of attached nymphs, 97.6 percent were alive on untreated outfits, 22.6 percent on treated. Home and commercial treatment showed no statistically significant difference in the number of tick bites.
The label for EPA Reg. No. 50404-3 agrees: pay particular attention to socks, trouser cuffs and shirt cuffs, and it says that in heavily infested areas protection from ticks is improved by wearing the cuffs inside footwear or taping pant cuffs around the legs. The factory-treated apparel label sets the limit: no insect protection product can guarantee complete protection from insects or insect bites, and the apparel does not protect against diseases or reactions from insect bites.
How long does factory-treated clothing last?
Longer than most people expect. The CDC says permethrin-treated items provide protection after multiple washings, and tells you to read the product label to find out how long. The Yellow Book is more specific: treated materials retain repellency or insecticidal activity after repeated launderings, and clothing treated before purchase is labeled for efficacy through many launderings.
The numbers live on the label. The EPA-accepted hang-tag for Insect Shield Repellent Apparel (EPA Reg. No. 74843-2, permethrin 0.52 percent) carries the line "REPELLENCY REMAINS EFFECTIVE FOR [70][50][25] WASHINGS," with the bracketed figures marked on the label as optional or alternate text, so the number a given garment claims varies. The same label warns that dry cleaning removes the active ingredient.
That tag is the pesticide label. The EPA treats factory-treated clothing as a pesticide product that must carry a pesticide use label, which on clothing is a hang-tag attached to the outside of the garment. Keep it.
How long does clothing you treat yourself last?
The label also tells you to keep doing the basics: avoid areas where pests are found, wear light-colored clothing with a long-sleeved shirt and long pants tucked into socks, and inspect your body daily for ticks. How you pull one off matters too.
How long does permethrin last on clothes, self treated versus factory treated?
Two weeks to six weeks if you treat it yourself; the Insect Shield hang tag, EPA Reg. No. 74843-2, is printed for 70, 50 or 25 washings. The CDC says you can buy permethrin-treated clothing and gear or treat items yourself, and lists boots, shirts, pants, socks and tents among the items that can be treated. For factory-treated clothing, the EPA requires manufacturers to submit efficacy data for pests of public health concern such as mosquitoes and ticks, and says it reviewed those data and found the clothing effective in repelling target pests.
| Treatment | EPA-accepted label | How long it lasts | Launderings | Re-treat rule |
|---|---|---|---|---|
| Self treated, aerosol spray | 0.5% Permethrin Aerosol Spray, EPA Reg. No. 71-1 | One clothing treatment lasts 2 weeks; residual protection for a minimum of two weeks | Holds up through several machine washings | Not more than once every two weeks; launder at least once before retreating |
| Self treated, spray | CIC Residual Insecticide No. 1, EPA Reg. No. 50404-3, permethrin 0.50% | A minimum of six weeks, 42 days, against ticks, chiggers, mites and mosquitoes | Holds up through several machine washings | After six weeks or after the sixth laundering |
| Factory treated apparel | Insect Shield Repellent Apparel hang tag, EPA Reg. No. 74843-2, permethrin 0.52% | Repellency remains effective for the number of washings printed on the tag | 70, 50 or 25 washings, carried on the label as alternate text; the garment's own tag shows which applies | Read the wash count on the hang tag; the CDC says the product label tells you how long protection lasts |
Two rules make the table usable. First, the CDC says permethrin-treated items provide protection after multiple washings and tells you to read the product label to find out how long protection will last, so your own tag or bottle outranks this table. Second, wash treated clothing separately. The EPA says small amounts of permethrin can come off in the wash, that only outer clothing is treated because outer clothing is most likely to contact the listed pests, and that the label instructs consumers to wash permethrin-treated clothing separately from non-treated clothing. NPIC gives the same instruction.
Fabric durability is counted in weeks and washings. The repellent on your exposed skin runs on a different clock, and we walk through it in how long picaridin lasts.
What do the CDC and EPA say about it?
The CDC's tick prevention page lists it among the steps before going outdoors: treat clothing and gear with products containing 0.5 percent permethrin, which it says can be used on boots, clothing and camping gear and remains protective through several washings, or buy treated clothing and gear instead. Its mosquito prevention page is briefer, telling people to wear clothing and gear treated with permethrin, which it calls an insecticide that kills or repels mosquitoes.
The EPA's position comes out of its registration process. It requires efficacy data for pests of public health concern such as mosquitoes and ticks, and says it reviewed those data for permethrin factory-treated clothing and found it effective in repelling target pests. Its 2009 revised assessment evaluated multiple exposure scenarios, including toddlers wearing or mouthing the clothing and military personnel wearing treated uniforms daily, and reported that all of them showed permethrin factory-treated clothing is unlikely to pose any significant immediate or long-term hazard to people wearing it. Permethrin was first registered for clothing use by the military in 1990, consumer factory-treated products followed in 2003, and it is still the only insect repellent used for factory treatment of clothing.
What does EPA say about the safety of permethrin treated clothing?
EPA states it plainly: "All exposure scenarios showed that permethrin factory-treated clothing is unlikely to pose any significant immediate or long-term hazard to people wearing the clothing." EPA reached that finding in a 2009 revised exposure and risk assessment covering multiple scenarios, including toddlers wearing or mouthing the clothing and military personnel who wear permethrin-treated uniforms daily. EPA says the April 2009 revision also evaluated short-term and long-term cancer risks to adults, youth and toddlers wearing the clothing, plus toddler object-to-mouth activity, and that "all scenarios resulted in risk estimates below our level of concern."
EPA addresses mothers and children directly: "Based on our review of scientific studies, there is no evidence of reproductive or developmental effects to mother or child following exposure to permethrin." EPA adds that the amount of permethrin allowed in clothing is very low, that exposure from wearing it is also low, and that available data show permethrin is poorly absorbed through the skin.
EPA also reviewed the efficacy data for permethrin factory-treated clothing and found it effective in repelling target pests. EPA also notes that small amounts of permethrin can come off in the wash, and that the label instructs consumers to wash treated clothing separately from non-treated clothing. Every line above is EPA describing permethrin factory-treated clothing, except the reproductive and developmental finding, which is EPA's statement about exposure to permethrin.
How is this different from a repellent you put on your skin?
Different job, different surface, different clock. Skin repellents go on exposed skin or the outside of clothing, never underneath. The EPA lists the active ingredients in registered skin-applied insect repellents: DEET, picaridin, IR3535, oil of lemon eucalyptus, p-menthane-3,8-diol, 2-undecanone, catnip oil and oil of citronella. Those products go where fabric does not: face, hands and other exposed areas of the body.
Durability is the sharpest contrast. The Yellow Book notes that clothing treated with other repellent products, such as DEET, protects against biting arthropods but will not last through washing and requires more frequent application. Permethrin bonds to the fabric and survives the laundry.
Neither replaces the other. Wear the treated clothing, cover exposed skin separately: that is the layering behind tick-bite prevention and mosquito-borne illness guidance alike.
What does treated clothing not do?
It does not make you invisible. The EPA-accepted label for factory-treated apparel carries two lines worth reading: that neither the apparel nor any other insect protection product can guarantee complete protection from insects or insect bites, and that it does not protect against diseases or reactions from insect bites. It does not work on everything, either. The Yellow Book states that permethrin-impregnated clothing and insect repellent have not been proven effective against tsetse flies.
And it does not retire the routine. The CDC still wants a tick check after you come indoors, a shower within two hours, which it says has been shown to reduce the risk of getting Lyme disease, and clothes tumble dried on high heat for 10 minutes to kill ticks riding in on dry fabric. Tick exposure can happen year-round, it notes, though ticks are most active April through September.
How should you wash and handle treated clothing?
Wash treated clothing separately. The EPA explains why: small amounts of permethrin can come off in the wash, only outer clothing is treated, and these products are not to be applied to certain clothing such as underwear.
Cats are the household exception. NPIC reports that cats are more sensitive to permethrin than dogs or people because it takes their bodies a long time to break it down, and that cats exposed by accident to products with high, 45 to 65 percent, levels of permethrin may seem anxious, may not walk normally, may have muscle tremors and seizures, and may die.
NPIC also notes that permethrin is highly toxic to fish and other animals that live in water, and to bees and other beneficial insects, and it says to apply these products outdoors in well ventilated areas protected from wind. One more reason to handle standing water around the house instead of spraying more.
Common questions
Can I dilute permethrin and use it on my skin?
No. The CDC says not to use permethrin products directly on skin, and the Yellow Book says it should never be applied to the skin, only to clothing, mosquito nets or other fabrics as directed on the label.
Does permethrin wash out of treated clothing?
Some does. The EPA says small amounts of permethrin can come off in the wash, which is why the label tells you to wash treated clothing separately. Factory-treated garments carry a wash count on the hang-tag. One 0.5 percent label says self-treated clothing should be re-treated after six weeks or after the sixth laundering. Another EPA-accepted 0.5 percent label, Reg. No. 71-1, says one clothing treatment lasts two weeks, so the interval depends on the product you bought.
Is this the same permethrin used for head lice and scabies?
Same active ingredient, different regulatory category. NPIC notes that some permethrin products treat scabies and head lice on people, and that those are drugs regulated by the U.S. Food and Drug Administration. Clothing treatments are pesticides regulated by the EPA, with directions for fabric only.
Can you spray too much permethrin on clothes?
Yes, and the labels say not to. The label for EPA Reg. No. 50404-3 says do not exceed recommended spraying times, and not to treat underwear, hats, caps or inner clothing. NPIC says to read the application instructions carefully, apply according to the label directions, and not to over-treat. NPIC says any pesticide product with permethrin will not do: look for one with specific instructions for treating clothing.
Is permethrin toxic to humans?
NPIC says permethrin is more toxic to insects than to people and dogs because insects cannot break it down as quickly. On treated clothing, the EPA says permethrin is poorly absorbed through the skin, that all exposure scenarios showed factory-treated clothing is unlikely to pose any significant immediate or long-term hazard to wearers, and, about permethrin exposure generally, that it found no evidence of reproductive or developmental effects to mother or child.
About Longsleeve
Longsleeve is an EPA-registered picaridin lotion (EPA Reg. No. 101457-1). It repels mosquitoes and ticks for up to 14 hours. It is fragrance-free, with nine disclosed ingredients.
None of this is medical advice. If you develop a rash or a fever after a bite, call your doctor and tell them what bit you.
More Longsleeve in your Google feed:
Sources
- CDC, About Permethrin-Treated Clothing and Gear. https://www.cdc.gov/mosquitoes/prevention/about-permethrin-treated-clothing-and-gear.html
- CDC, Preventing Tick Bites. https://www.cdc.gov/ticks/prevention/index.html
- CDC, Preventing Mosquito Bites. https://www.cdc.gov/mosquitoes/prevention/index.html
- CDC Yellow Book, Mosquitoes, Ticks, and Other Arthropods. https://www.cdc.gov/yellow-book/hcp/environmental-hazards-risks/mosquitoes-ticks-and-other-arthropods.html
- EPA, Repellent-Treated Clothing. https://www.epa.gov/insect-repellents/repellent-treated-clothing
- EPA, Skin-Applied Repellent Ingredients. https://www.epa.gov/insect-repellents/skin-applied-repellent-ingredients
- NPIC, Permethrin General Fact Sheet (PDF). https://npic.orst.edu/factsheets/PermGen.pdf
- NPIC, Insect Repellents Fact Sheet. https://npic.orst.edu/factsheets/repellents.html
- NPIC, Permethrin Treated Clothing. https://npic.orst.edu/pest/mosquito/ptc.html
- EPA Pesticide Product Label, Insect Shield Repellent Apparel, EPA Reg. No. 74843-2 (PDF). https://www3.epa.gov/pesticides/chem_search/ppls/074843-00002-20170515.pdf
- EPA Pesticide Product Label, CIC Residual Insecticide No. 1, EPA Reg. No. 50404-3 (PDF). https://www3.epa.gov/pesticides/chem_search/ppls/050404-00003-20151006.pdf
- EPA Pesticide Product Label, 0.5% Permethrin Aerosol Spray, EPA Reg. No. 71-1 (PDF). https://www3.epa.gov/pesticides/chem_search/ppls/000071-00001-20150716.pdf
- PubMed, Miller NJ, Rainone EE, Dyer MC, Gonzalez ML, Mather TN. Tick bite protection with permethrin-treated summer-weight clothing. Journal of Medical Entomology, 2011, volume 48, issue 2, pages 327 to 333. https://pubmed.ncbi.nlm.nih.gov/21485369/
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