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Skin-applied active

DEET

N,N-diethyl-meta-toluamide

DEET, the active ingredient in many repellents, was developed by the U.S. Army in 1946, EPA says.

Source and detail: EPA

DEET, N,N-diethyl-meta-toluamide, is the active ingredient in many repellent products; EPA's DEET page says it was developed by the U.S. Army in 1946 and registered for the general public in 1957, and that an estimated one-third of the U.S. population uses it every year. What people get wrong is the mechanism: EPA says that rather than killing biting bugs, DEET 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
EPA statusRegistered; 505 products in EPA's tool
Protection, per EPA's tool2 to 12 h mosquitoes, 2 to 10 h ticks
Youngest ageNo age limit (EPA, CDC)
GearNPIC says it can damage certain plastics, rubber, vinyl and synthetics; a label spares nylon, cotton and wool.
PetsEPA lists cats, dogs and horses as use sites; nothing on pets unless the label says so.

Product counts and hours are what EPA's repellent search tool listed on 2026-08-18; the other three lines are the agencies' words, sourced below.

Eleven questions.

One line each. Open any source for the full text and the exact quote.

What is it, and where does it come from?

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

How does EPA treat it?

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

What strengths are registered, and does strength change protection?

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)

How long does EPA say it protects?

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

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

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

What do the agencies say about children?

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)

What do CDC and WHO say about pregnancy?

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

What do NPIC and EPA report about absorption and toxicity?

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

Does it damage plastics, fabrics or gear?

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

What do the agencies say about pets?

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

Which studies are on the record?

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

Put it beside another.

DEET vs PicaridinDEET vs IR3535DEET vs Oil of lemon eucalyptusDEET vs PMDDEET vs 2-UndecanoneDEET vs Catnip oilDEET vs CitronellaDEET vs Other plant oilsDEET vs Permethrin

All ten actives 631 products by ingredient

Sources on this page.

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

  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/