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DEET Safety: What the Evidence Actually Says

By Andrew Rothaus, Founder ·

DEET has been in public use since 1957. The EPA reassessed it in 1998 and 2014 and both times concluded that normal use does not present a health concern to the general population, including children. Reported effects are most often eye irritation, then skin irritation. The CDC calls severe reactions rare, and NPIC says reported seizures mostly followed misuse.

A mosquito landing on human skin

How long has DEET been in use, and how many people use it?

The chemical name is N,N-diethyl-meta-toluamide. The EPA says the U.S. Army developed it in 1946 and that it was registered for use by the general public in 1957. The EPA estimates about one-third of the U.S. population uses DEET every year, and NPIC puts the figure at about 30 percent. Formulations registered for direct application to human skin contain from 5 to 99 percent DEET. In the EPA's words, "Rather than killing them, DEET works by making it hard for these biting bugs to smell us."

What did the EPA conclude when it reregistered DEET in 1998?

Pesticides first registered before November 1984 had to be reregistered against newer standards. The EPA finished that review in April 1998, and was specific: "In studies using laboratory animals, DEET generally has been shown to be of low acute toxicity. It is slightly toxic by the eye, dermal and oral routes and has been placed in Toxicity Category III (the second lowest of four categories) for these effects."

The conclusion: 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 human risk assessment "identified no toxicologically significant effects in animal studies," and the agency classified DEET as "a Group D carcinogen (not classifiable as a human carcinogen.)"

Conditions came with it. Every product had to carry a series of 14 statements covering application method, precautions for children and directions for medical attention. Child-safety claims had to come off every end-use label, because the agency called them "misleading and irreconcilable with the intended use and pesticidal ingredients of DEET products." Separately, it wrote that "there appears to be no correlation between the percent active ingredient in the product and its safety."

What did the 2014 review add?

The EPA revisited DEET under Registration Review and posted an Interim Decision on September 24, 2014. The findings were narrow: "no additional data are required at this time" and "no changes to the affected registrations or their labeling are needed at this time." 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."

One piece is unfinished. A final decision on the registration review case "will occur only after the EPA has completed an Endocrine Disruptor Screening under FFDCA section 408(p)," and the agency says DEET sits lower on the screening priority list than chemicals currently being tested. NPIC's archived technical sheet reported that no data were found on endocrine effects from DEET exposure, and none on chronic health effects in humans.

What does the NPIC toxicity summary say?

NPIC, a cooperative agreement between Oregon State University and the EPA, publishes a public DEET fact sheet. Products in the eyes may cause irritation, pain and watery eyes. People who have left DEET products on their skin for extended periods have experienced irritation, redness, rash and swelling. People who have swallowed them have experienced stomach upset, vomiting and nausea. On seizures the qualifier matters: "Very rarely, exposure to DEET has been associated with seizures in people. Most of these reactions have happened after drinking products with DEET in them or using the products in ways that do not follow label directions."

On cancer, NPIC says researchers have not found any evidence that DEET causes cancer in animals or humans, and that the "not classifiable as a human carcinogen" classification means there is not enough evidence to say that it does or does not cause cancer. Its archived technical fact sheet carries the animal numbers behind the low-toxicity label: an acute oral LD50 in rats of 2,170 to 3,664 mg/kg and an acute dermal LD50 in rabbits of 4,280 mg/kg.

What do the documented adverse-effect reports actually show?

Two datasets dominate. The first is poison center reports, which NPIC's archived sheet summarizes for 1993 to 1997: symptoms depended on the pathway of exposure and were most frequently associated with ocular exposure, and dermal symptoms were reported in 5 percent of reports to poison control centers following DEET exposure. That is a share of reports, not a share of users.

The second is the EPA's 1998 seizure record. The agency counted, since 1960, "14 cases of seizure, including four deaths, potentially related to DEET exposure, for which other more likely causes have not been identified," with another 32 cases reported to a national DEET registry then still under review, so the total would "fall between 14 and 46 cases since 1960," a range "subject to both over- and under-reporting." Against use, it wrote: "Given only 14 to 32 cases since 1960 (the first case was reported in 1961) and 50-80 million people using DEET each year, the observed incidence of recognized seizures is about one per 100 million users."

The EPA did not claim the cases were caused by DEET, and it did not clear them either: "The Agency has analyzed these incidents and cannot, at this time, conclude that these seizures are directly related to DEET exposure. However, neither can the Agency definitely conclude that they are not DEET-related." It offered coincidence as one explanation, citing an estimated 15,000 to 20,000 afebrile seizures in children aged 0 to 19 annually and an estimated 17 million children using DEET perhaps as often as 10 times a year. The FIFRA Scientific Advisory Panel agreed the reported incidences were inconclusive.

It tightened labels anyway, saying improved warnings were prudent for a chemical applied directly to skin and used so widely. The CDC's Yellow Book adds the clinical frame: "Severe reactions to insect repellents are rare."

What does the CDC say about DEET and pregnancy?

The CDC's mosquito bite prevention page points pregnant and breastfeeding women to EPA-registered repellents used as directed, and lists DEET among the active ingredients. Its Yellow Book adds that "Other than the safety tips listed above, EPA does not recommend any additional precautions for using registered repellents on children or on women who are pregnant or lactating."

NPIC describes a double-blind, randomized trial testing DEET to prevent malaria in pregnancy: women in their second and third trimesters applied a product with 20 percent DEET to their arms and legs daily. DEET crossed the placenta and was detected in 8 percent of cord blood samples in that trial. No significant adverse effects were detected in mother or fetus, and infants showed no differences in development or survival at birth or at age one. Travel raises its own questions, covered in the dengue travel guide.

What is the guidance for children?

The EPA approves DEET for use on children with no age restriction, and sets no restriction on the percentage for children, "since data do not show any difference in effects between young animals and adult animals in tests done for product registration." In 1998 it wrote that reproductive and developmental toxicity data gave no evidence that would lead it to believe the chemical was uniquely toxic to infants or children. The Yellow Book likewise says repellents containing DEET can be used on children without age restriction.

Other bodies publish tighter numbers, worth seeing side by side. NPIC reports that the American Academy of Pediatrics has recommended that DEET not be used on children younger than 2 months, that it be applied no more than once a day for children older than two months, that products with the lowest concentration available be used, and that parents avoid children's hands, eyes and mouths. A CDC fact sheet for travelers says to use no more than 30 percent DEET on a child and not to put insect repellent on babies younger than 2 months. More on age rules in repellents for kids.

How much DEET gets into the body?

Some does. NPIC says that when DEET was applied to the skin of volunteers, a small amount was taken into the body, it can be found in the blood up to 12 hours after application, the liver breaks it down, it leaves mainly through the urine, and nearly all of it is eliminated within 24 hours.

A few things raise absorption. NPIC reports that applying DEET with alcohol increases uptake compared with DEET alone, that drinking alcohol may also increase absorption, and that sunscreen products containing DEET may cause more of it to be taken in through the skin. NPIC also notes that people have had adverse reactions when they applied it under clothing, and that the amount absorbed may increase when treated skin is covered. Hence the label line "DO NOT USE UNDER CLOTHING." Treated fabric is a separate approach, covered in permethrin-treated clothing.

Common questions

Has the EPA ever found DEET to cause cancer?

No. The EPA classified DEET as a Group D carcinogen, meaning not classifiable as a human carcinogen. NPIC explains that this means there is not enough evidence to say that it does or does not cause cancer, and that researchers have not found evidence that it causes cancer in animals or humans.

How long does DEET keep bugs off?

The EPA says studies in its database indicate that DEET repels ticks for about two to ten hours, and mosquitoes from two to twelve hours, depending on the percentage in the product. The Yellow Book says studies suggest efficacy tends to peak around 50 percent, with higher concentrations not offering a marked increase in protection time against mosquitoes.

Does it affect sunscreen?

The Yellow Book says limited data show that DEET-containing repellents applied over sunscreen decrease the sunscreen's sun protection factor by one-third, and advises separate products, sunscreen first.

What should I do if I react to a repellent?

The EPA says to stop using the product, wash treated skin, and call your local poison control center or physician, taking the container with you if you see a doctor.

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 are pregnant, treating an infant, or dealing with a reaction to any product, talk to your clinician, and follow the label on whatever you use.

Sources

  1. EPA, DEET. https://www.epa.gov/insect-repellents/deet
  2. EPA, R.E.D. Facts: DEET, EPA-738-F-95-010, April 1998 (PDF). https://www3.epa.gov/pesticides/chem_search/reg_actions/reregistration/fs_PC-080301_1-Apr-98.pdf
  3. EPA, Reregistration Eligibility Decision (RED) for DEET, EPA738-R-98-010, approved April 13, 1998 (PDF). https://www3.epa.gov/pesticides/chem_search/reg_actions/reregistration/red_PC-080301_1-Apr-98.pdf
  4. EPA, DEET Interim Registration Review Decision, Case Number 0002, posted September 24, 2014, docket EPA-HQ-OPP-2012-0162. https://www.regulations.gov/document/EPA-HQ-OPP-2012-0162-0012
  5. EPA, Using Insect Repellents Safely and Effectively. https://www.epa.gov/insect-repellents/using-insect-repellents-safely-and-effectively
  6. NPIC, DEET General Fact Sheet. https://npic.orst.edu/factsheets/DEETgen.html
  7. NPIC, DEET Technical Fact Sheet (archived). https://npic.orst.edu/factsheets/archive/DEETtech.html
  8. NPIC, Can I apply DEET under my clothes? https://npic.orst.edu/faq/deet.html
  9. CDC, Preventing Mosquito Bites. https://www.cdc.gov/mosquitoes/prevention/index.html
  10. CDC Yellow Book, Mosquitoes, Ticks, and Other Arthropods. https://www.cdc.gov/yellow-book/hcp/environmental-hazards-risks/mosquitoes-ticks-and-other-arthropods.html
  11. CDC, Insect Repellents Help Prevent Malaria and Other Diseases Spread by Mosquitoes (PDF). https://www.cdc.gov/parasites/media/pdfs/2024/05/repellents_2015.pdf

Last reviewed 2026-08-16 · every claim on this page is sourced above