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DEET vs Permethrin

The same eleven questions, side by side, each answer in the agency's words. No verdict from us: we sell a product built on one of these actives, so the agencies do the talking.

DEETN,N-diethyl-meta-toluamide
Permethrina synthetic pyrethroid insecticide

Per EPA's tool

DEET

Registered; 505 products in EPA's tool; 2 to 12 h mosquitoes, 2 to 10 h ticks.

Permethrin

Registered since 1979; CDC says fabric only, never skin; Not in EPA’s tool.

What is it, and where does it come from?

DEET

EPA says DEET, made for skin, works by making it hard for biting bugs to smell us.

Source and detail: EPA

DEET, N,N-diethyl-meta-toluamide, is what EPA's DEET page calls the active ingredient in many repellent products, designed for direct application to people's skin. EPA says it was developed by the U.S. Army in 1946 and registered for use by the general public in 1957, and that rather than killing biting bugs it works by making it hard for them to smell us.

DEET (chemical name, N,N-diethyl-meta-toluamide) is the active ingredient in many repellent products. It is widely used to repel biting pests such as mosquitoes and ticks. Every year, an estimated one-third of the U.S. population use DEET to protect them from mosquito-borne illnesses like West Nile Virus, the Zika virus or malaria and tick-borne illnesses like Lyme disease and Rocky Mountain spotted fever.

EPA, DEET (epa.gov/insect-repellents/deet), fetched 2026-09-22

DEET is designed for direct application to people's skin to repel insects. Rather than killing them, DEET works by making it hard for these biting bugs to smell us. After it was developed by the U.S. Army in 1946, DEET was registered for use by the general public in 1957. Approximately 120 products containing DEET are currently registered with EPA by about 30 different companies.

EPA, DEET (epa.gov/insect-repellents/deet), fetched 2026-09-22
Permethrin

A synthetic pyrethroid that NPIC says acts like natural chrysanthemum extracts, registered by EPA as an insecticide.

Source and detail: EPA, NPIC

Permethrin is an insecticide in the pyrethroid family; NPIC's permethrin fact sheet says pyrethroids are synthetic chemicals that act like natural extracts from the chrysanthemum flower. EPA's Repellent-Treated Clothing page describes it as a broad spectrum, non-systemic, synthetic pyrethroid insecticide, registered as an insecticide for a variety of settings, and says that when used to pre-treat clothing it is an insect repellent.

Permethrin is an insecticide in the pyrethroid family. Pyrethroids are synthetic chemicals that act like natural extracts from the chrysanthemum flower.

NPIC, Permethrin General Fact Sheet

Permethrin is a broad spectrum, non-systemic, synthetic pyrethroid insecticide that targets adults and larvae of many species of biting, chewing, scaling, soil, and flying invertebrates. Permethrin is registered by the EPA as an insecticide for use in a variety of settings. When used to pre-treat clothing, it is an insect repellent.

EPA, Repellent-Treated Clothing

How does EPA treat it?

DEET

Registered, about 120 products per EPA; its 1998 review found repellents containing DEET present no health concern.

Source and detail: EPA

Registered: EPA's DEET page says approximately 120 products containing DEET are registered with EPA by about 30 companies. EPA's 1998 reregistration decision concluded that insect repellents containing DEET do not present a health concern; its registration review risk assessment found no risks of concern because no toxic effects have been identified when it is used as a dermally applied insect repellent, with a final decision waiting on Endocrine Disruptor Screening.

DEET is designed for direct application to people's skin to repel insects. Rather than killing them, DEET works by making it hard for these biting bugs to smell us. After it was developed by the U.S. Army in 1946, DEET was registered for use by the general public in 1957. Approximately 120 products containing DEET are currently registered with EPA by about 30 different companies.

EPA, DEET (epa.gov/insect-repellents/deet), fetched 2026-09-22

After completing a comprehensive re-assessment of DEET, we concluded that insect repellents containing DEET do not present a health concern. Consumers are advised to read and follow label directions when using any pesticide product, including insect repellents. Based on extensive toxicity testing, we believe that the normal use of DEET does not present a health concern to the general population, including children. We completed this review and issued a reregistration decision (called a RED) in 1998.

EPA, DEET (epa.gov/insect-repellents/deet), fetched 2026-09-22

The human health risk assessment concluded that there are no risks of concern because no toxic effects have been identified when used as a dermally applied insect repellent, and there is no dietary or occupational exposure for DEET. However, a Final Decision on the DEET registration review case will occur only after the EPA has completed an Endocrine Disruptor Screening under FFDCA section 408(p).

EPA, DEET (epa.gov/insect-repellents/deet), fetched 2026-09-22
Permethrin

Registered since 1979, EPA says; on clothing by the military since 1990, factory-treated consumer clothing since 2003.

Source and detail: EPA

Registered since 1979, per EPA's Repellent-Treated Clothing page, which says permethrin was first registered in 1990 as a repellent on clothing by the military and that factory-treated consumer clothing was first registered in 2003. EPA's sentence is "The only insect repellent currently used for factory treatment of clothing is permethrin."

Permethrin has been registered since 1979. It was first registered in 1990 for use as a repellent on clothing by the military. At about the same time, we also approved permethrin as a spray for use on clothing and gear by consumers, as well as for commercial factory treatment of clothing and various types of gear. In 2003, we first registered consumer-oriented, permethrin factory-treated clothing products.

EPA, Repellent-Treated Clothing

The only insect repellent currently used for factory treatment of clothing is permethrin.

EPA, Repellent-Treated Clothing

What strengths are registered, and does strength change protection?

DEET

EPA registers 5 to 99%; CDC says higher concentrations generally protect longer, with DEET peaking near 50%.

Source and detail: CDC Yellow Book, EPA

EPA's DEET page says formulations registered for direct application to human skin contain from 5 to 99 percent DEET. CDC's Yellow Book says higher concentrations generally provide longer protection regardless of the active ingredient, and that studies suggest DEET efficacy tends to peak at approximately 50 percent, with concentrations above that not offering a marked increase in protection time against mosquitoes.

Products containing DEET currently are available to the public in a variety of liquids, lotions, sprays, and impregnated materials (e.g., towelettes, roll on). Formulations registered for direct application to human skin contain from 5 to 99% DEET.

EPA, DEET (epa.gov/insect-repellents/deet), fetched 2026-09-22

In general, higher concentrations of active ingredients provide longer duration of protection, regardless of the active ingredient. Products with <10% active ingredient might offer only limited protection, often 1-2 hours. Products that offer sustained-release or controlled-release (microencapsulated) formulations, even with lower active ingredient concentrations, might provide longer protection times. Studies suggest that DEET efficacy tends to peak at a concentration of approximately 50% and that concentrations above that do not offer a marked increase in protection time against mosquitoes.

CDC Yellow Book, Mosquitoes, Ticks, and Other Arthropods (Wayback Machine capture 2026-09-19)
Permethrin

Permethrin at 0.5% on clothing repels and kills ticks, chiggers and mosquitoes, CDC says; labels list 0.50%.

Source and detail: CDC Yellow Book, EPA stamped label

CDC's Yellow Book says that at a concentration of 0.5 percent, permethrin-treated clothing repels and kills ticks, chiggers, mosquitoes and other biting and nuisance arthropods. The accepted label for a permethrin clothing treatment, EPA Reg. No. 50404-3, gives its active ingredient as permethrin 0.50 percent, and the accepted hang-tag label for factory-treated apparel, EPA Reg. No. 74843-2, gives permethrin at 0.52 percent.

At a concentration of 0.5%, permethrin-treated clothing repels and kills ticks, chiggers, mosquitoes, and other biting and nuisance arthropods.

CDC Yellow Book, Mosquitoes, Ticks, and Other Arthropods (Wayback Machine capture 2026-09-19)

ACTIVE INGREDIENT: Permethrin*……..……. 0.50%

EPA stamped label, CIC Residual Insecticide No. 1, EPA Reg. No. 50404-3, accepted October 6, 2015

Permethrin 0.52%

EPA stamped label, Insect Shield Repellent Apparel, EPA Reg. No. 74843-2, dated May 15, 2017

How long does EPA say it protects?

DEET

EPA says 2 to 12 hours for mosquitoes and 2 to 10 for ticks, depending on the percentage.

Source and detail: EPA, U.S. EPA

EPA's DEET page says studies in its database indicate DEET repels ticks for about two to ten hours and mosquitoes from two to twelve hours, depending on the percentage of DEET in the product. In EPA's repellent search tool, Ben's 100 Insect Repellent, EPA Reg. No. 56575-7, at 98.11 percent DEET, lists 10 hours for mosquitoes and 10 for ticks. EPA says protection times vary because testing conditions differ, and that the tool's database was last updated in June 2019.

Studies in EPA's database indicate that DEET repels ticks for about two to ten hours, and mosquitoes from two to twelve hours depending on the percentage of DEET in the product.

EPA, DEET (epa.gov/insect-repellents/deet), fetched 2026-09-22

Ben's 100 Insect Repellent | 10 | 10 | DEET | 98.11 | Tender Corp. | 56575-7

EPA, Find the Repellent that is Right for You, search results for DEET, cfpub.epa.gov/oppref/insect_s

While this technical information is based on scientific testing guidelines and approved study methods, there are variations in the resulting protection times because of differences in the testing conditions.

EPA, Find the Repellent that is Right for You

Any products listed are for informational purposes only. Inclusion of a product listed/referenced is not an endorsement. * EPA and the U.S. Government do not endorse any product or service. * The information in this database was last updated in June 2019.

U.S. EPA, Find the Repellent that is Right for You
Permethrin

Labels say six weeks or six washes when you treat clothing, 70, 50 or 25 washings when factory-treated.

Source and detail: CDC Yellow Book, EPA stamped label

The accepted label for a 0.5 percent permethrin clothing treatment, EPA Reg. No. 50404-3, says protection lasts a minimum of six weeks, with retreatment after six weeks or the sixth laundering; the hang-tag for factory-treated apparel, EPA Reg. No. 74843-2, says repellency remains effective for a bracketed 70, 50 or 25 washings. CDC's Yellow Book says treated materials retain repellency after repeated launderings but should be retreated per the label.

This product contains an active ingredient, which actually binds to the fabric being treated, providing residual protection, which lasts a minimum of six weeks [42 days], and holds up through several machine washings. Follow standard laundering procedures. Clothing should be retreated after six weeks [42 days] or after the sixth laundering to maintain adequate protection.

EPA stamped label, CIC Residual Insecticide No. 1, EPA Reg. No. 50404-3, accepted October 6, 2015

REPELLENCY REMAINS EFFECTIVE FOR [70][50][25] WASHINGS

EPA stamped label, Insect Shield Repellent Apparel, EPA Reg. No. 74843-2, dated May 15, 2017

Permethrin-treated materials retain repellency or insecticidal activity after repeated launderings but should be retreated as described on the product label to provide continued protection. Clothing treated before purchase is labeled for efficacy through many launderings.

CDC Yellow Book, Mosquitoes, Ticks, and Other Arthropods (Wayback Machine capture 2026-09-19)

ACTIVE INGREDIENT: Permethrin*……..……. 0.50%

EPA stamped label, CIC Residual Insecticide No. 1, EPA Reg. No. 50404-3, accepted October 6, 2015

Which pests do accepted labels name, and what does CDC say those pests carry?

DEET

A 15% label names mosquitoes, gnats, no-see-ums, biting flies, ticks, chiggers and fleas.

Source and detail: EPA notification label

The accepted label for a 15 percent DEET aerosol, EPA Reg. No. 4822-380, claims protection from mosquitoes, gnats, no-see-ums, biting flies, ticks, chiggers and fleas. On ticks, the label's exact wording is "including ticks that may cause Lyme disease."

EFFECTIVE PROTECTION from Mosquitoes, Gnats, No-See-Ums, Biting Flies, Ticks (including ticks that may cause Lyme disease), Chiggers and Fleas

EPA notification label, OFF! Insect Repellent II, EPA Reg. No. 4822-380, 15% DEET aerosol, November 13, 2009
Permethrin

Labels name mosquitoes, ticks, chiggers, mites, ants, flies and midges.

Source and detail: EPA stamped label

The accepted label for a 0.5 percent permethrin clothing treatment, EPA Reg. No. 50404-3, says it repels and kills mosquitoes, chiggers, mites and ticks, in the label's words "including Ticks which carry Lyme Disease and Rocky Mountain Spotted Fever." The accepted hang-tag label for factory-treated apparel, EPA Reg. No. 74843-2, claims that it repels mosquitoes, ticks, ants, flies, chiggers and midges.

To repel & kill mosquitoes, chiggers, mites and ticks, including Ticks which carry Lyme Disease and Rocky Mountain Spotted Fever.

EPA stamped label, CIC Residual Insecticide No. 1, EPA Reg. No. 50404-3, accepted October 6, 2015

REPELS MOSQUITOES, TICKS, ANTS, FLIES, CHIGGERS, AND MIDGES

EPA stamped label, Insect Shield Repellent Apparel, EPA Reg. No. 74843-2, dated May 15, 2017

ACTIVE INGREDIENT: Permethrin*……..……. 0.50%

EPA stamped label, CIC Residual Insecticide No. 1, EPA Reg. No. 50404-3, accepted October 6, 2015

What do the agencies say about children?

DEET

No age limit, EPA and CDC say, and EPA sets no percentage limit for children.

Source and detail: CDC Yellow Book, EPA

EPA's DEET page states that DEET "is approved for use on children with no age restriction," and that there is no restriction on the percentage of DEET in a product for use on children, since registration tests showed no difference in effects between young and adult animals. CDC's Yellow Book says insect repellents containing DEET, picaridin, IR3535 and 2-undecanone can be used on children without age restriction.

DEET is approved for use on children with no age restriction. There is no restriction on the percentage of DEET in the product for use on children, since data do not show any difference in effects between young animals and adult animals in tests done for product registration.

EPA, DEET (epa.gov/insect-repellents/deet), fetched 2026-09-22

Insect repellents containing DEET, picaridin, IR3535, and 2-undecanone can be used on children without age restriction

CDC Yellow Book, Mosquitoes, Ticks, and Other Arthropods (Wayback Machine capture 2026-09-19)
Permethrin

No minimum age stated; EPA's 2009 review called treated clothing unlikely to pose significant hazard, toddlers included.

Source and detail: EPA

No CDC, EPA or label source we read states a minimum age for wearing permethrin-treated clothing. The closest agency statement is EPA's: its 2009 revised exposure and risk assessment evaluated multiple exposure scenarios for permethrin factory-treated clothing, including toddlers wearing or mouthing the clothing, and all scenarios showed the clothing is unlikely to pose any significant immediate or long-term hazard to people wearing it.

Our 2009 revised exposure and risk assessment evaluated multiple exposure scenarios for permethrin factory-treated clothing, including toddlers wearing or mouthing the clothing, and military personnel who wear permethrin-treated uniforms on a daily basis. 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, Repellent-Treated Clothing

What do CDC and WHO say about pregnancy?

DEET

CDC lists it for pregnant and breastfeeding women; one 897-woman trial found no adverse effects to one year.

Source and detail: CDC, McGready R

CDC's Preventing Mosquito Bites page lists DEET among the active ingredients it names, and says that when used as directed, EPA-registered insect repellents are "proven safe and effective, even for pregnant and breastfeeding women." McGready 2001, a double-blind randomized trial of 897 women, found no adverse neurologic, gastrointestinal or dermatologic effects from daily DEET in the second and third trimesters, and none on survival, growth or development at birth or one year.

Use EPA-registered insect repellents with one of the following active ingredients. When used as directed, EPA-registered insect repellents are proven safe and effective, even for pregnant and breastfeeding women.

CDC, Preventing Mosquito Bites (Wayback Machine capture 2026-09-16)

When used as directed, EPA-registered insect repellents are proven safe and effective, even for pregnant and breastfeeding women. DEET Picaridin (known as KBR 3023 and icaridin outside the United States)

CDC, Preventing Mosquito Bites (Wayback Machine capture 2026-09-16)

The safety of daily application of N, N-diethyl-m-toluamide (DEET) (1.7 g of DEET/day) in the second and third trimesters of pregnancy was assessed as part of a double-blind, randomized, therapeutic trial of insect repellents for the prevention of malaria in pregnancy (n = 897). No adverse neurologic, gastrointestinal, or dermatologic effects were observed for women who applied a median total dose of 214.2 g of DEET per pregnancy (range = 0-345.1 g).

McGready R, et al. Safety of the insect repellent N,N-diethyl-M-toluamide (DEET) in pregnancy. Am J Trop Med Hyg. 2001 Oct;65(4):285-9. PMID 11693870

DEET crossed the placenta and was detected in 8% (95% confidence interval = 2.6-18.2) of cord blood samples from a randomly selected subgroup of DEET users (n = 50). No adverse effects on survival, growth, or development at birth, or at one year, were found. This is the first study to document the safety of DEET applied regularly in the second and third trimesters of pregnancy.

McGready R, et al. Am J Trop Med Hyg. 2001 Oct;65(4):285-9. PMID 11693870
Permethrin

EPA says no evidence of reproductive or developmental effects to mother or child; no CDC statement found.

Source and detail: EPA

EPA's Repellent-Treated Clothing page says that, based on its review of scientific studies, there is no evidence of reproductive or developmental effects to mother or child following exposure to permethrin. No CDC or WHO page we read makes a permethrin-specific pregnancy statement.

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, Repellent-Treated Clothing

What do NPIC and EPA report about absorption and toxicity?

DEET

NPIC says a small amount absorbs through skin; EPA calls it generally low in acute toxicity.

Source and detail: EPA, NPIC

NPIC says a small amount of DEET applied to skin is taken into the body, more when alcohol is also on the skin. EPA's 1998 R.E.D. FACTS sheet calls DEET generally of low acute toxicity and a Group D carcinogen, not classifiable as a human carcinogen. EPA's 1998 reregistration decision counted 14 seizure cases since 1960, including four deaths, potentially related to DEET: an observed incidence of about one recognized seizure per 100 million users each year.

When DEET was applied to the skin of volunteers by researchers, they found that a small amount of the DEET was taken into the body through the skin. When DEET and alcohol are applied to the skin, more DEET is taken into the skin compared with DEET alone. Drinking alcohol may also cause more DEET to be absorbed through the skin. Sunscreen products that contain DEET may cause more DEET to be taken into the body through the skin.

NPIC, DEET General Fact Sheet

DEET generally is of low acute toxicity, and, based on the available toxicological data, the Agency believes that the normal use of DEET does not present a health concern to the general U.S. population (the Agency's human risk assessment has identified no toxicologically significant effects in animal studies.) DEET has been classified as a Group D carcinogen (not classifiable as a human carcinogen.)

EPA, R.E.D. FACTS: DEET, EPA-738-F-95-010, April 1998

In summary, since 1960, there have been 14 cases of seizure, including four deaths, potentially related to DEET exposure, for which other more likely causes have not been identified. An additional 32 cases of seizure reported to the national DEET registry are currently under review.

EPA, Reregistration Eligibility Decision (RED) DEET, EPA738-R-98-010, approved April 13, 1998

people using DEET each year, the observed incidence of recognized seizures is about one per 100 million users.

EPA, Reregistration Eligibility Decision (RED) DEET, EPA738-R-98-010, approved April 13, 1998
Permethrin

EPA says treated clothing gives low exposure and skin absorbs it poorly; NPIC says it may irritate skin.

Source and detail: EPA, NPIC

EPA's Repellent-Treated Clothing page says the amount of permethrin allowed in clothing is very low, that human exposure from wearing permethrin factory-treated clothing is low, and that available data show permethrin is poorly absorbed through the skin. NPIC says people who get permethrin on their skin may have irritation or tingling, burning and itching at that spot, and in the eyes it can cause redness, pain or burning.

The amount of permethrin allowed in clothing is very low, and scientific studies indicate that human exposure resulting from wearing permethrin factory-treated clothing also is low. Available data show that permethrin is poorly absorbed through the skin.

EPA, Repellent-Treated Clothing

When people get permethrin on their skin, they may have irritation or tingling, burning and itching at that spot. If permethrin gets in the eyes it can cause redness, pain or burning.

NPIC, Permethrin General Fact Sheet

Does it damage plastics, fabrics or gear?

DEET

NPIC says it can damage certain plastics, rubber, vinyl and synthetics; a label spares nylon, cotton and wool.

Source and detail: EPA amended reregistration label, NPIC

NPIC's DEET technical fact sheet calls DEET a plasticizer that can damage certain rubber, plastic, vinyl or elastic materials, including contact lenses, eyeglass frames and lenses, watch crystals, combs, painted and varnished surfaces, and certain synthetic or treated fabrics. The accepted label for a 10 percent DEET product, EPA Reg. No. 121-53, says it will not damage nylon, cotton or wool.

DEET is a plasticizer and can damage certain rubber, plastic, vinyl, or elastic materials such as contact lenses, eyeglass frames and lenses, watch crystals, combs, painted and varnished surfaces, and certain synthetic or treated fabrics.

NPIC, DEET Technical Fact Sheet (archived)

Will not damage nylon, cotton, or wool.

EPA amended reregistration label, Cutter Insect Repellent #10GE, EPA Reg. No. 121-53, 10% DEET, March 18, 2009
Permethrin

CDC says never on skin, only clothing, nets and fabrics; a label adds tents, sleeping bags and backpacks.

Source and detail: CDC Yellow Book, EPA stamped label

CDC's Yellow Book says permethrin should never be applied to skin, only to clothing, nets or other fabrics as the label directs. The label for a 0.5 percent permethrin treatment, EPA Reg. No. 50404-3, lists netting, tents, sleeping bags, backpacks, hammocks and camping chairs, with no treating inside a sleeping bag and only the exterior surfaces of a tent sprayed; the hang-tag for factory-treated apparel, EPA Reg. No. 74843-2, says dry cleaning removes the active ingredient.

Permethrin should never be applied to the skin but only to clothing, mosquito nets, or other fabrics as directed on the product label.

CDC Yellow Book, Mosquitoes, Ticks, and Other Arthropods (Wayback Machine capture 2026-09-19)

GEAR: MOSQUITO NETTING, NETS, TENTS, CANOPIES, SCREEN ENCLOSURES, SLEEPING BAGS, BACKPACKS, GROUNDCLOTHS, HAMMOCKS AND CAMPING CHAIRS: Do not treat inside of sleeping bag. Spray exterior surfaces of tent only.

EPA stamped label, CIC Residual Insecticide No. 1, EPA Reg. No. 50404-3, accepted October 6, 2015

DRYCLEANING REMOVES ACTIVE INGREDIENT- DO NOT DRY CLEAN

EPA stamped label, Insect Shield Repellent Apparel, EPA Reg. No. 74843-2, dated May 15, 2017

ACTIVE INGREDIENT: Permethrin*……..……. 0.50%

EPA stamped label, CIC Residual Insecticide No. 1, EPA Reg. No. 50404-3, accepted October 6, 2015

What do the agencies say about pets?

DEET

EPA lists cats, dogs and horses as use sites; nothing on pets unless the label says so.

Source and detail: EPA, NPIC

EPA's 1998 R.E.D. FACTS sheet lists cats, dogs, horses and pet living and sleeping quarters among DEET's use sites. EPA tells consumers not to use any product on pets unless the label clearly states it is for animals. NPIC says reports of pets exposed to DEET in amounts that would make them sick are rare; overexposed pets have shown vomiting, shaking, excitement, lack of coordination and seizures.

N,N-diethyl-meta-toluamide (DEET) is an insect repellent used in households/domestic dwellings, on the human body and clothing being worn, on cats, dogs, horses and pet living/sleeping quarters. There are no food uses.

EPA, R.E.D. FACTS: DEET, EPA-738-F-95-010, April 1998

Do not use any product on pets or other animals unless the label clearly states it is for animals.

EPA, Using Insect Repellents Safely and Effectively

Reports of pets being exposed to DEET in amounts that would make them sick are rare. Pets that have been overexposed to DEET have shown varying effects, including vomiting, shaking, excitement, lack of coordination, and seizures.

NPIC, DEET General Fact Sheet
Permethrin

NPIC says cats are more sensitive than dogs or people because they break it down slowly.

Source and detail: NPIC

NPIC says permethrin is more toxic to insects than to people and dogs, and that cats are more sensitive than dogs or people because their bodies take a long time to break it down. NPIC's technical fact sheet describes a report of 11 cats intentionally treated with products containing 45 to 65 percent permethrin: all 11 were hospitalized, with muscle tremors, seizures, incoordination and agitation, and four died.

Permethrin is more toxic to insects than it is to people and dogs. This is because insects can't break it down as quickly as people and dogs. Cats are more sensitive to permethrin than dogs or people because it takes their bodies a long time to break it down.

NPIC, Permethrin General Fact Sheet

A report of 11 cats intentionally treated with products containing 45-65% permethrin described adverse effects including muscle tremors, seizures, incoordination and agitation after exposure. Of the 11 cats that were treated, all were hospitalized, and four died after the exposure.

NPIC, Permethrin Technical Fact Sheet (archived)

Which studies are on the record?

DEET

One trial found 20% DEET and 20% picaridin performed equally, with 97.4% protection over five hours.

Source and detail: Carroll JF, Van Roey K

Van Roey 2014 (PLoS Neglected Tropical Diseases) reported an overall five-hour protection rate of 97.4 percent, with picaridin 20 percent performing equally well as DEET 20 percent. Carroll 2010 (Journal of Medical Entomology) found formulations of deet, picaridin and IR3535 at 20 percent or more active ingredient highly effective against lone star ticks over 12 hours, with fewer than 10 percent of ticks crossing the treatment bands.

Based on a total of 4996 mosquitoes collected on negative control persons, the overall five hour protection rate was 97.4% [95%CI: 97.1-97.8%], not decreasing over time. Picaridin 20% performed equally well as DEET 20% and better than picaridin 10%.

Van Roey K, et al. Field evaluation of picaridin repellents reveals differences in repellent sensitivity between Southeast Asian vectors of malaria and arboviruses. PLoS Negl Trop Dis. 2014 Dec 18;8(12):e3326. PMID 25522134

Formulations containing > or = 20% active ingredient were highly effective, with <10% of the ticks crossing through the treatment bands for any challenge during the 12 h. At least 40% of ticks exposed to any formulation for any challenge fell or crawled off the volunteers.

Carroll JF, Benante JP, Kramer M, Lohmeyer KH, Lawrence K. Formulations of deet, picaridin, and IR3535 applied to skin repel nymphs of the lone star tick (Acari: Ixodidae) for 12 hours. J Med Entomol. 2010 Jul;47(4):699-704. PMID 20695288

There was no difference in effectiveness between the 20% spray and 20% lotion formulations of picaridin. The 10% IR3535 lotion was significantly less effective than the formulations with higher concentrations of repellent. In the formulations tested, deet, picaridin, and IR3535 provided lasting protection against A. americanum.

Carroll JF, et al. J Med Entomol. 2010 Jul;47(4):699-704. PMID 20695288
Permethrin

One trial found 3.36 times fewer tick bites on subjects wearing permethrin-treated outfits than untreated ones.

Source and detail: Miller NJ

Miller 2011 (Journal of Medical Entomology) found that subjects wearing outfits treated with permethrin received 3.36 times fewer tick bites than subjects wearing untreated outfits, with no statistically significant difference between commercial permethrin treatment and the do-at-home application method. In the same study, 97.6 percent of nymphs attached to subjects in untreated outfits were alive, against 22.6 percent on subjects in repellent-treated outfits.

Subjects wearing outfits treated with permethrin received 3.36 times fewer tick bites than subjects wearing untreated outfits. No statistically significant differences in number of tick bites were detected between commercial permethrin treatment (19.33%) and the do-at-home permethrin application method (24.67%).

Miller NJ, Rainone EE, Dyer MC, Gonzalez ML, Mather TN. Tick bite protection with permethrin-treated summer-weight clothing. J Med Entomol. 2011 Mar;48(2):327-33. PMID 21485369

On subjects wearing untreated outfits, 97.6% of attached nymphs were alive, whereas significantly fewer (22.6%) attached nymphs were alive on subjects wearing repellent-treated outfits.

Miller NJ, et al. J Med Entomol. 2011 Mar;48(2):327-33. PMID 21485369

Sources on this page.

21 sources. Every quote was fetched on or before 2026-09-22 and is stored with the page. Last reviewed 2026-09-22. All ten actives.

  1. EPA, DEET (epa.gov/insect-repellents/deet), fetched 2026-09-22. https://www.epa.gov/insect-repellents/deet
  2. CDC Yellow Book, Mosquitoes, Ticks, and Other Arthropods (Wayback Machine capture 2026-09-19). https://www.cdc.gov/yellow-book/hcp/environmental-hazards-risks/mosquitoes-ticks-and-other-arthropods.html
  3. EPA, Find the Repellent that is Right for You, search results for DEET, cfpub.epa.gov/oppref/insect_s. https://cfpub.epa.gov/oppref/insect_s/search_results.cfm
  4. EPA, Find the Repellent that is Right for You. https://www.epa.gov/insect-repellents/find-repellent-right-you
  5. EPA notification label, OFF! Insect Repellent II, EPA Reg. No. 4822-380, 15% DEET aerosol, November 13, 2009. https://www3.epa.gov/pesticides/chem_search/ppls/004822-00380-20091113.pdf
  6. CDC, Preventing Mosquito Bites (Wayback Machine capture 2026-09-16). https://www.cdc.gov/mosquitoes/prevention/index.html
  7. McGready R, et al. Safety of the insect repellent N,N-diethyl-M-toluamide (DEET) in pregnancy. Am J Trop Med Hyg. 2001 Oct;65(4):285-9. PMID 11693870. https://pubmed.ncbi.nlm.nih.gov/11693870/
  8. NPIC, DEET General Fact Sheet. https://npic.orst.edu/factsheets/DEETgen.html
  9. EPA, R.E.D. FACTS: DEET, EPA-738-F-95-010, April 1998. https://www3.epa.gov/pesticides/chem_search/reg_actions/reregistration/fs_PC-080301_1-Apr-98.pdf
  10. EPA, Reregistration Eligibility Decision (RED) DEET, EPA738-R-98-010, approved April 13, 1998. https://www3.epa.gov/pesticides/chem_search/reg_actions/reregistration/red_PC-080301_1-Apr-98.pdf
  11. NPIC, DEET Technical Fact Sheet (archived). https://npic.orst.edu/factsheets/archive/DEETtech.html
  12. EPA amended reregistration label, Cutter Insect Repellent #10GE, EPA Reg. No. 121-53, 10% DEET, March 18, 2009. https://www3.epa.gov/pesticides/chem_search/ppls/000121-00053-20090318.pdf
  13. EPA, Using Insect Repellents Safely and Effectively. https://www.epa.gov/insect-repellents/using-insect-repellents-safely-and-effectively
  14. Van Roey K, et al. Field evaluation of picaridin repellents reveals differences in repellent sensitivity between Southeast Asian vectors of malaria and arboviruses. PLoS Negl Trop Dis. 2014 Dec 18;8(12):e3326. PMID 25522134. https://pubmed.ncbi.nlm.nih.gov/25522134/
  15. Carroll JF, Benante JP, Kramer M, Lohmeyer KH, Lawrence K. Formulations of deet, picaridin, and IR3535 applied to skin repel nymphs of the lone star tick (Acari: Ixodidae) for 12 hours. J Med Entomol. 2010 Jul;47(4):699-704. PMID 20695288. https://pubmed.ncbi.nlm.nih.gov/20695288/
  16. NPIC, Permethrin General Fact Sheet. https://npic.orst.edu/factsheets/PermGen.html
  17. EPA, Repellent-Treated Clothing. https://www.epa.gov/insect-repellents/repellent-treated-clothing
  18. EPA stamped label, CIC Residual Insecticide No. 1, EPA Reg. No. 50404-3, accepted October 6, 2015. https://www3.epa.gov/pesticides/chem_search/ppls/050404-00003-20151006.pdf
  19. EPA stamped label, Insect Shield Repellent Apparel, EPA Reg. No. 74843-2, dated May 15, 2017. https://www3.epa.gov/pesticides/chem_search/ppls/074843-00002-20170515.pdf
  20. NPIC, Permethrin Technical Fact Sheet (archived). https://npic.orst.edu/factsheets/archive/Permtech.html
  21. Miller NJ, Rainone EE, Dyer MC, Gonzalez ML, Mather TN. Tick bite protection with permethrin-treated summer-weight clothing. J Med Entomol. 2011 Mar;48(2):327-33. PMID 21485369. https://pubmed.ncbi.nlm.nih.gov/21485369/