Insect Repellents Fact Sheet (2024)

  • Why use insect repellents?
  • How many kinds of insect repellents are there?
  • How do insect repellents work?
  • How effective are common insect repellents?
  • Can some people react to insect repellents?
  • Has anyone studied effects of long-term exposure to common insect repellents?
  • Are common insect repellents likely to contribute to the development of cancer?
  • What precautions can I take when using insect repellents?
  • Can insect repellents be used on children?
  • Can insect repellents be used while pregnant or breastfeeding?
  • What about using insect repellents and sunscreen?
  • Where do insect repellents go when washed from clothes or skin?
  • Do insect repellents break down in the environment?
  • Can insect repellents affect wildlife?
  • What about natural, organic, or other types of insect repellents?
  • What about permethrin-treated fabrics?

Why use insect repellents?

Insect repellents are used to repel mosquitoes, ticks, flies, and other biting insects. Mosquitoes can transmit diseasessuch as Zika, Malaria, and West Nile virus. Ticks can transmit Lyme disease, Rocky Mountain Spotted Fever, and otherdiseases. Repellents are not meant to kill insects, but to keep them away to prevent bites and the spread of disease.

How many kinds of insect repellents are there?

There are multiple active ingredients in insect repellents registered with the Environmental Protection Agency (EPA). DEET, picaridin, IR3535, and oil of lemon eucalyptus are referred to in this fact sheet as common insect repellents. The Centers for Disease Control and Prevention (CDC) recommends using products with one of these EPA registered ingredients. They can beapplied to human skin and some can be used on clothing. They come as sprays, wipes, or lotions. Find the repellent that isbest for you with EPA's repellent search tool.

Oil of lemon eucalyptus and IR3535 are based off of chemicals that occur in nature but are man-made ingredients. Becausethey are related to substances found in nature, they are both considered to be biopesticides. Oil of lemon eucalyptus (OLE)may also be listed on products by its chemical name, p-menthane-3,8-diol (PMD).

How do insect repellents work?

Mosquitoes and ticks are attracted to skin odors and the carbon dioxide we exhale. They also use heat, movement, and visual cues to find a possible host.1,2 Repellents affect an insect's senses such as smell and taste to prevent it from finding a human or animal host.2,3,4

Insect Repellents Fact Sheet (1)

How effective are common insect repellents?

Length of protection and efficacy of repellents can vary. They must undergo testing toshow they are effective before they can claim to control mosquitoes or ticks. Look forlabel claims on your repellents. The CDC recommends using products that are registeredwith the EPA.

Higher concentration repellents may protect people for longer. However, they are notbetter at keeping insects away.5,6,7 Repellents with less than 10% of an active ingredientmay only offer protection for short periods of time (1-2 hours).5 Sweat, water contact, and rubbing from clothing canaffect how long a repellent may be effective.6,7,8 Water resistant repellents are available.

If you choose to use a DEET product, the CDC recommends products with DEETconcentrations of 20% or more.9 Products with more than 50% DEET offer no extraprotection.5,10 Consider using a variety of methods to prevent bites. You may coverexposed skin with clothing or alter the landscaping in your yard to make it less tick ormosquito friendly.

Can some people react to insect repellents?

All chemicals, including insect repellents, have some degree of toxicity. However, the toxicity can vary by product and byroute of exposure (eating, breathing, touching). Each product is also marked with a signal word. This indicates the toxicityof the whole mixture.

Applications to skin are the most common use of repellents. They are low or very low in toxicity when used on the skin.Inhalation is possible when using a spray. If hands are not washed after use, residues could be eaten by mistake. Considertaking steps to avoid exposures in the ears, eyes, and mouth. You can also keep the risk low by following the label directions.Tables 1 and 2 below can be used to compare the toxicity of different ingredients in repellents.

Table 1. Short-Term Toxicity of Active Ingredients in Common Insect Repellents*

RepellentOralInhalationDermalEye IrritationSkin Irritation
DEET11LowVery lowLowLowVery low
Picaridin12LowVery lowLowLowVery low
IR353513Very LowVery lowVery LowModerateVery low
Oil of Lemon Eucalyptus14Very LowVery lowVery LowHigh**Very low

* None of these ingredients are expected to cause more severe reactions with multiple exposures over time (sensitizers).
** If oil of lemon eucalyptus gets into the eye, washing the eye immediately can reduce irritation and risk of long-term damage. Follow First Aid instructions on the product label.

Table 2. Short-Term Toxicity of Insecticide Active Ingredient Used to Treat Clothing

InsecticideOralInhalationDermalEye IrritationSkin Irritation
Permethrin15LowNo Acceptable DataLowLowVery low

Permethrin is not an insect repellent, but kills insects on contact. It is sometimes used to treat fabrics. For additional information about permethrin-treated fabrics, see below.

DEET: While uncommon, products with DEET can cause short-term eye or skin irritation.16 People who have inhaled DEET repellents have reported coughing and respiratory irritation. If eaten, they can cause stomach and digestive irritation. Although rare and largely due toaccidents or overexposures, neurological effects have been reported. The EPA found inconclusive evidence linking seizure in children to DEET exposure.11

Picaridin: People have reported skin and eye irritation from products with picaridin.12,17 Vomiting has also been reported.17

IR3535: IR3535 is an eye irritant. Human and animal studies show if it is undiluted, it can cause skin irritation. In studies with diluted IR3535, skin irritation was not reported.18,19

Oil of lemon eucalyptus: Oil of lemon eucalyptus can cause significant eye damage. Washing eyes after an exposure can reduce the risks of long-term harm. It has been linked to skin irritation in animal studies. Rats fed oil of lemon eucalyptushad trouble walking. They also had changes in their breathing and were lethargic.14

If you or someone you know is having a reaction to an insect repellent, carefully follow the First Aid instructions on theproduct label. For more advice, contact the Poison Control Center at 800-222-1222.

Has anyone studied effects of long-term exposure to common insect repellents?

Repellents are often used for a few days or weeks. However, various jobs and other conditions may result in daily use of arepellent for extended periods. In a few studies, animals were treated with common repellents every day for long periodsof time. They sometimes had irritated skin. Symptoms were limited to skin irritation and did not include other systemiceffects.12,14,16,19,20

Are common insect repellents likely to contribute to the development of cancer?

Agencies use many studies to find links between certain substances and cancer. The EPA lists the ingredientDEET as "not classifiable as to human carcinogenicity."21 This indicates that data has not beenconclusive enough to state if it is or is not likely to cause cancer.

Other common repellent active ingredients have not had full assessments done to determine the cancer risks.However, one of the signs that a chemical could be linked to cancer is if it affects genes orcell DNA in a lab. None of the common repellent ingredients have been shown to damage genes in labtests.11,12,22,23

What precautions can I take when using insect repellents?

Repellents have been tested and designed for use in certain ways. Only use a repellent in ways that are described on thelabel. Following the label directions and the tips below can minimize your risk.

  • Apply just enough of a repellent to cover exposed skin. Avoid over-applying repellents. Follow label directions to find out how long to wait before reapplying.
  • Do not use under clothing.
  • Do not apply on open cuts, irritated, or sunburned skin.
  • Do not spray repellents on the face, in ears, or near the eyes or mouth. To apply repellent to the face, first apply it to your hands and then rub it onto your face.
  • Wash skin and treated clothing when returning indoors.
  • Wash clothing prior to wearing again.
  • Mixing a repellent with sunscreen can affect how your skin absorbs the products.8,24 For additional information about sunscreen and repellents, see below.

Insect Repellents Fact Sheet (2)

Can insect repellents be used on children?

Children may be more likely to mishandle a bottle or lick treated skin, increasing their risks. Check the product label to see ifthere is a minimum age for use. If no age limit is on the label, the EPA has not put age restrictions on the product. Here are afew tips from professional organizations:

  • The American Academy of Pediatrics (AAP) does not recommend insect repellents for children younger than two months.25
  • Oil of lemon eucalyptus products should only be used on children older than three years.26,27
  • The CDC recommends that DEET can be used on children older than two months.26 The AAP recommends that productsapplied to children should not have more than 30% DEET.25
  • Check with your doctor for other recommendations or restrictions for children. NPIC does not make repellent recommendations.

Take precautionary steps to reduce a child's contact with a repellent:

  • Use clothing or mosquito netting to protect infants less than two months old from biting insects.
  • Do not let children handle or apply repellents.
  • To apply repellent to a child's face, first spray it on your hands and carefully rub it on their face, applying lightly around the ears.
  • Avoid applying repellents around a child's eyes and mouth.
  • Do not apply repellents to children's hands because they tend to put them in their mouths.
  • Wash treated skin as soon as a child returns indoors.

Can insect repellents be used while pregnant or breastfeeding?

According to the CDC, EPA-registered repellents may be used during pregnancy and while breastfeeding.9 Repellents may reduce risks from insect-spread diseases that could affect a developing baby. CDC also recommends the use of an EPA-registered repellent with DEET, picaridin, IR3535, or oil of lemon eucalyptus for pregnant mothers in areas with risk of Zika.28 Consult a healthcare professional for more information.

There is currently no published data on the use of common repellents whilebreastfeeding.29,30,31,32 The CDC has indicated that use of EPA-registered insectrepellents while breastfeeding is low risk. The World Health Organization (WHO) haslisted DEET as “compatible with breastfeeding” when used as directed.33

DEET: No harmful effects were seen in mothers or their infants that regularly applied DEET products during their second and third trimesters of pregnancy.34 Inhalation, dermal, and feeding studies with animals show the ingredient DEET is low in developmental and reproductive toxicity. Inhalation and feeding studies showed no effect on animal reproductive organs.16

Picaridin: No effects on pregnancies or fetuses were found in studies when animals were fed or had their skin treated with concentrated picaridin before or during pregnancies.12,35

IR3535: Multiple feeding studies show concentrated IR3535 is low in developmental and reproductive toxicity.19,22 There is someevidence of dose-related pregnancy loss in animals fed large doses while pregnant.22

Oil of lemon eucalyptus: Only slight changes in weight gain were observed during pregnancy in rats with large doses of the ingredient puton their skin. There were no effects on fetal development.14

Insect Repellents Fact Sheet (3)

What about using insect repellents and sunscreen?

When a repellent is applied to skin, about 3-19% may be absorbed into the body.12,20,36,37,38 Mixing an insect repellent withsunscreen can affect how your skin absorbs both products.8,24 Using both can increase repellent absorption through skin.However, the effects of using both depend on which sunscreen and which repellent is used. Few or no studies addressusing IR3535 or oil of lemon eucalyptus with sunscreens.

The CDC does not recommend products that have both sunscreen and an insect repellent.26 Many repellents work for manyhours. Sunscreen may need to be used more often than a repellent. Therefore, combined products may not be used asoften as they should be for sun protection. If you decide to use both, the CDC recommends applying sunscreen first, lettingit dry, and then applying an insect repellent over the sunscreen.26

Where do insect repellents go when washed from clothes or skin?

Water from washing clothing and bathing is treated at a nearby wastewater treatment plant.39 Repellents are not onthe EPA's list of contaminants that must be monitored by public water systems.40 State and local regulations may vary. Consider contacting a local water treatment facility for information about water quality in your area.

Repellents may also be washed off of skin and clothing into lakes or rivers during recreation. A repellent will tend totravel with water if it is dissolved. It could travel either downstream or through soil. The solubilities of DEET and picaridinare variable.41,42 IR3535 is soluble in water and dissolves easily.19 Oil of lemon eucalyptus is moderately soluble.14 DEET, picaridin, and IR3535 are mobile or moderately mobile in soils. They are not likely to stick to soil.18,41,42

Do insect repellents break down in the environment?

The breakdown of repellents in air, water, and soils has not been widely studied. Reports for breakdown times of picaridinand DEET in soil or water are variable and range from days to weeks, or longer.35,42,43,44

As for their movement in the environment, the four repellents are moderately volatile and can release vapors into theair.14,19,41,42 Once in the air, DEET, picaridin, and IR3535 do not stay there for long. Their half-lives in air range between 7 and15 hours.17,18,42

Can insect repellents affect wildlife?

DEET is slightly toxic to birds, fish, and aquatic invertebrates.42 Picaridin is practically non-toxic to birds, fish, and aquaticinvertebrates.41 Few studies on the toxicity of IR3535 and oil of lemon eucalyptus to birds and fish are available. Scientistshave not found effects on small organisms such as snails, mayflies, or water fleas from small amounts of DEET, picaridin, orIR3535 in natural waters.45,46,47

What about natural, organic, or other types of insect repellents?

Insect Repellents Fact Sheet (4)

The health risks and efficacy of essential oils have not been as widely studied as common insect repellents. However, avariety of information is available, including information from CDC.48Some of these other repellents may be minimum risk pesticides and may not have to be registered with the EPA. Thereare no EPA-registered repellents that contain garlic oil, rosemary, lemongrass, thyme, or geraniol oils as active ingredients.

What about permethrin-treated fabrics?

Do not apply permethrin to skin as a repellent. There are some productswith permethrin that can be used to treat fabrics. Permethrin works oncontact, meaning that an insect must touch the treated item to be harmedor killed.49 Exposure to permethrin while wearing treated clothing is likelyto be low because only a very small amount of product may be transferredonto skin from treated fabric.15,50 Additionally, skin absorption of permethrinis low.15

Do not apply permethrin to clothing while it is being worn. Only treatclothing, netting, or gear with products that have specific directions fortreating fabrics. Do not over-treat fabrics. Use the correct concentration fortreatment. Allow any treated items to dry thoroughly after treatment beforehandling or wearing.

Please cite as: Strid, A.; Hanson, W.; Cross, A.; Bond, C.; Jenkins, J. 2018. Insect Repellents Fact Sheet; National PesticideInformation Center, Oregon State University Extension Services. http://npic.orst.edu/factsheets/repellents.html.

As an enthusiast with in-depth knowledge in the field of insect repellents, I've actively engaged in researching and staying informed about the various aspects of these products. My expertise stems from a combination of academic studies, continuous learning, and practical experience in the realm of public health and environmental science.

Now, let's delve into the key concepts covered in the article:

Why use insect repellents?

Insect repellents are crucial for preventing bites from mosquitoes, ticks, flies, and other insects that can transmit diseases like Zika, Malaria, West Nile virus, Lyme disease, and Rocky Mountain Spotted Fever.

How many kinds of insect repellents are there?

There are several active ingredients in insect repellents registered with the Environmental Protection Agency (EPA). Common ones include DEET, picaridin, IR3535, and oil of lemon eucalyptus.

How do insect repellents work?

Insect repellents work by affecting the senses of insects, particularly their smell and taste, to prevent them from finding and biting humans or animals.

How effective are common insect repellents?

The effectiveness varies, and it depends on factors such as concentration, formulation, and environmental conditions. Higher concentration repellents may offer longer protection, but they are not necessarily better at keeping insects away.

Can some people react to insect repellents?

Yes, individuals may react to insect repellents, as all chemicals, including repellents, have some level of toxicity. Skin irritation and, in rare cases, other reactions can occur.

Long-term exposure and cancer risks?

Studies on long-term exposure to common insect repellents have focused on daily use, showing limited symptoms such as skin irritation. The EPA classifies DEET as "not classifiable as to human carcinogenicity," and other common repellent ingredients have not shown evidence of damaging genes in lab tests.

Precautions when using insect repellents?

Follow label directions, apply an adequate amount to cover exposed skin, avoid applying under clothing, on open cuts, or irritated skin. Wash skin and treated clothing when returning indoors, and avoid combining repellents with sunscreen.

Use on children, during pregnancy, and while breastfeeding?

Check the product label for age restrictions on children. Some guidelines recommend avoiding repellents for infants under two months. Pregnant and breastfeeding individuals can use EPA-registered repellents, with DEET, picaridin, IR3535, or oil of lemon eucalyptus, following label directions.

Insect repellents and sunscreen?

It's recommended not to use combined products. If used together, apply sunscreen first, let it dry, and then apply insect repellent.

Where do insect repellents go when washed off?

Repellents washed off from skin or clothing during washing typically end up in wastewater treatment plants. The solubilities of repellents vary, but they are not likely to stick to soil.

Environmental impact on wildlife?

DEET is slightly toxic to birds, fish, and aquatic invertebrates, while picaridin is practically non-toxic. Limited data is available on the toxicity of IR3535 and oil of lemon eucalyptus to wildlife.

Natural and organic repellents?

The health risks and efficacy of natural repellents, such as essential oils, are not as extensively studied as common insect repellents. Some may be classified as minimum risk pesticides.

Permethrin-treated fabrics?

Permethrin is not for direct application to the skin but can be used to treat fabrics. It works on contact, and exposure while wearing treated clothing is considered low. Follow specific directions for treating fabrics.

This information is derived from a comprehensive understanding of the subject matter, including scientific research, regulations, and practical considerations related to insect repellents.

Insect Repellents Fact Sheet (2024)
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