Insect Repellents: How to Use Them Safely

Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on Feb 6, 2024.

Ingredients | How they work | Safety | Insect-borne diseases | Most Common Insect Repellents | How to apply | Side effects | Use with sunscreen | Use in children & during pregnancy | Conclusion

Introduction

Insect repellents keep mosquitoes, ticks, biting flies and other pests away. Often just called bug spray, they also help to prevent serious insect-borne diseases, like malaria, Lyme disease or Zika. Ingredients can vary but may include DEET, picaridin, 2-undecanone, Oil of Lemon Eucalyptus or IR3535, which are all EPA-registered products. 

To be registered by EPA, these products must have safety and effectiveness data, which the US Environmental Protection Agency (EPA) evaluates before allowing them to be marketed.

But many consumers have questions about insect repellents. Is DEET safe? Can I use an insect repellent on my child? What are the side effects? Here, we tackle these questions and more in this overview of insect repellents.

 

What are the most common ingredients in insect repellents?

Insect repellents found at the stores commonly include DEET (N, N-diethyl-m-toluamide) or picaridin (KBR 3023). Other available options include 2-undecanone (BioUD), Oil of Lemon Eucalyptus (OLE) and IR3535. These active ingredients are found in EPA-registered skin-applied insect repellents. Always follow the instructions for use listed on the bottle or label.

EPA characterizes the active ingredients in DEET and picaridin as conventional insect repellents. OLE, PMD, IR3535, and 2-undecanone are considered biopesticide repellents as they are derived from, or are synthetic versions of, natural materials.

Review effectiveness of common insect repellent ingredients below.

How do insect repellents work?

Humans attract mosquitoes and other blood feeding insects by their breath and skin odors. The insect is attracted to the carbon dioxide in a human's breath.

Repellents are effective only at the skin area and close to the treated surface, so mosquitoes may still be seen flying nearby. Repellents contain an ingredient that makes the person unattractive for biting; however, repellents do not kill the insect.

Repellents with higher concentrations (percentages) of active ingredient usually provide longer-lasting protection.

Insects and arachnids that bite in self-defense instead of to feed -- such as yellow jackets, bees, wasps, hornets, and certain ants or spiders -- may not be effectively repelled with insect repellents. In these cases, covering up with clothing and face protection may be your best option.

Are insect repellents safe?

Before they can be marketed, most skin-applied repellents must be registered by the U.S. Environmental Protection Agency (EPA). Active ingredient names such as DEET, picaridin, and permethrin have been shown to be effective in clinical trials and are registered with the EPA for use as insect repellents on skin or clothing.

When the EPA registers a repellent, they evaluate the product for effectiveness and potential side effects on humans and the environment. An EPA registered insect repellent is not expected to cause serious effects to humans or the environment when used as directed. The EPA evaluation assures that the product does not pose risks to vulnerable populations, including children and pregnant women.

The CDC recommends that consumers use repellent products that have been registered by EPA.

Learn More from the EPA: Repellents: Protection against Mosquitoes, Ticks and Other Arthropods

What diseases are caused by insects?

Not only do insect repellents keep mosquitoes, ticks, biting flies, gnats and other bugs away, insect repellents are a safe and effective way to prevent insect-borne diseases. The U.S. Centers for Disease Control and Prevention (CDC) recommend the use of insect repellents to prevent mosquito-borne diseases.

• Mosquito bites can lead to: West Nile virus, Malaria, Dengue fever, Chikungunya virus, Encephalitis, Yellow Fever (rare in US), Zika virus
• Ticks bites can cause: Lyme disease, Rocky Mountain Spotted Fever (RMSF), Powassan virus, Ehrlichiosis, Encephalitis

Over 249 million cases of malaria and 619,000 deaths occurred in 2022, with most of them in Africa. Deaths due to malaria occur mostly in children under 5 years of age in sub-Saharan Africa.

Mosquitoes that cause West Nile Virus may be biting in the early morning (dusk) and at sunset (dawn), so be sure to apply repellent at these times.

Insect repellents are also useful to prevent bites, skin eruptions and rashes that may be caused by an insect's bite. Mosquito bites can cause severe skin irritation through an allergic reaction to the mosquito's saliva.

How effective are the most common insect repellents?

DEET (Brands: Off, Cutter, Ultrathon, Sawyer)

Studies have shown DEET (N, N-diethyl-m-toluamide) is very effective against insects such as mosquitoes, ticks, chiggers, fleas, and some flies. DEET is a synthetic chemical compound originally developed in the 1950's for military use. DEET can protect you 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.

DEET is considered the 'gold standard' of insect repellents. It's available in concentrations ranging from 5% to 99%, but concentrations above 50% have not been shown to be more effective. A higher concentration does not mean DEET will work better; it means that it will be effective for a longer period of time. 

• DEET is available in lotions, sprays, and wipes for skin application. Long-acting formulations gives roughly 6 to 12 hours of protection and contain roughly 30% DEET.
• DEET can damage synthetic fibers, certain plastics, and watch crystals.
• Allergic reactions and serious side effects are rare. However, rash, mild irritation, urticaria (itching), and skin eruptions have been reported.

The CDC states that DEET is safe for children and infants older than 2 months, and the American Academy of Pediatrics (AAP) recommends that DEET solutions no greater than 30% in concentration be used in children. Avoid prolonged, excessive use or internal consumption in children.

Picaridin (Cutter, Natrapel)

Picaridin (KBR 3023) is available in 5% to 20% concentrations and is an effective repellent for flies, mosquitoes, fleas, chiggers, and ticks. 

• Picaridin is a synthetic chemical that mimics the natural compound piperine found in black pepper. Spray products with at least 20% picaridin have worked as well or better than some Deet-based ones.
• An advantage of picaridin over DEET is that it does not damage plastic or fabric and may be less sticky to use on skin than DEET. 
• The various brand names are available in spray and wipes for application to the skin.

DEET and Picaridin insect repellents have demonstrated a higher degree of effectiveness in peer-reviewed, scientific literature. Products containing these active ingredients typically provide longer-lasting protection than others.

IR3535 (Avon Skin So Soft Bug Guard Plus, Bull Frog Mosquito Coast)

IR3535 is available in concentrations from 7.5% to 20%, and is sold in combination with a sunscreen. Effective in repelling mosquitoes and ticks

• The CDC does not recommend using combination repellent and sunscreen products because the sunscreen will need to be applied more often than the repellent, and excessive use of the repellent may lead to side effects. It's best to apply each product separately; first the sunscreen then the insect repellent. Follow the reapplication and safe use instructions for each product.
• Some studies have questioned the effectiveness of the lower 7.5% concentration of the IR3535 product.
• IR3535 is available as a lotion and a spray.

Oil of Lemon Eucalyptus (Repel Lemon Eucalyptus, Cutter Lemon Eucalyptus, Coleman Botanicals)

Oil of Lemon Eucalyptus (OLE) is a plant-based repellent. P-menthane 3,8-diol (PMD) is the active ingredient in Oil of Lemon Eucalyptus.

The EPA states OLE provides 6 hours worth of protection against mosquito bites, biting flies, and gnats. The CDC states that OLE should NOT be used in children less than 3 years of age. Brands include Repel, Cutter and Murphy's Naturals.

• OLE is registered with the EPA, and is available as a spray. It can cause eye or skin irritation so use caution. Do not consume (swallow) by mouth.
• According to the CDC, when OLE was compared to DEET for mosquitoes found in the U.S., OLE is only about half as effective as DEET, and provided similar protection to lower concentrations of DEET. It may also repel ticks.
• OLE is often marketed as a “natural” insect repellent, but may still cause skin irritation or toxicity if swallowed. It is not an "essential oil".

Permethrin (Sawyer Premium Permethrin Clothing Insect Repellent)

Permethrin is available as a spray for clothes, insect nets, sleeping bags, shoes, and boots. It is NOT intended for direct application to the skin.

• Permethrin is a synthetic pyrethroid contact insecticide for gear and clothing ONLY used to repel and kill ticks, chiggers, mosquitoes, and other biting and nuisance arthropods.
• Clothing and other items must be treated 24 to 48 hours in advance of travel to allow them to dry.
• It remains active for several weeks, even after laundering, but retreat clothing and gear as directed on label.
• Clothing that is pre-treated with permethrin before purchase remains active through 70 launderings.

2-Undecanone or BioUD (BiteBlocker)

• BioUD (2-undecanone 7.75%) is a synthetic pesticide, registered with the EPA but assigned a low toxicity rating. It is derived from wild tomato plants (Lycopersicon hirsutum Dunal f. glabratum C. H. Müll).
• In studies against the mosquitoes Aedes aegypti (L.) and Aedes albopictus Skuse, when 2-undecanone was compared to DEET 7% to 30%, overall, 2-undecanone was found to be an effective repellent for mosquitoes (up to 6 hours) and ticks (up to 2.5 hours).

Catnip oil (Nepeta cataria, also known as catmint)

The ingredient is extract of Oil Nepeta cataria which is a member of the mint family of plants (Labiatae). Catnip is a herb that grows year-round and grows wild in most parts of the United States. It is registered with the EPA.

• It is used as an active ingredient for direct application to human skin to repel black flies, mosquitoes and other biting insects.
• Reapplication after six hours will be necessary. Researchers have reported that catnip oil is about 10 times more effective than DEET.
• The EPA concludes that no risks to human health are expected due to low toxicity and current use as a food ingredient by the general public without any reported adverse effects on human health. However, it can can lead to eye irritation.

Oil of Citronella

Oil of citronella is distilled from two grass varieties. It can be formulated into sprays, lotions, sunscreen products, and is commonly found in repellent candles. It works by masking scents that are attractive to insects. Oil of citronella is EPA registered.

• Oil of citronella repels insects rather than killing them. It works short-term on mosquitoes but not ticks.
• May cause irritation to the skin and eyes, skin allergies, cough or throat irritation.
• Some oil of citronella products should not be used on children less than 6 months old unless directed by a healthcare provider.

Learn More: EPA Guidelines on Skin-Applied Repellent Ingredients

How do I apply bug spray?

Judicious use of insect repellents is important. Apply them when you plan to be outside and only to exposed areas of the skin. Do not spray or apply repellent under clothing. Use only enough repellent to cover but not saturate the skin. Do not apply repellent to open wound areas, and avoid spraying directly onto your face.

Choose a repellent that provides protection for the amount of time that you will be outdoors. Frequent reapplication is usually not needed. Always follow the directions on the label for time between applications. Spray aerosols outside in ventilated areas and keep away from food. Wash the treated skin area with soap and water when you have returned indoors.

It is best to spray repellent into your hands, then rub carefully around the face, eyes and the mouth. When applying insect repellents to children, avoid applying to their hands, around their eyes, or to any skin areas that are cut or irritated. Wash your hands after application. 

If you want to use a sunscreen and a bug spray at the same time, apply the sunscreen first and then the insect repellent. Follow the application directions from each product. It's recommended to use separate products as sunscreen needs to be applied more often, and this will help to limit an excessive dose of insect repellent.

Can I apply bug spray to my clothing?

You can apply DEET or permethrin to your clothing, but DEET can stain clothing and tends to feel sticky.

Sprays containing permethrin are available specifically for clothes, mosquito nets, sleeping bags, shoes, and hiking boots. Clothing that has permethrin imbedded can be purchased, as well. DO NOT apply permethrin directly to your skin.

You can cover-up with clothing instead of using insect repellent, but you may still get bites. 

What are common side effects with insect repellents?

• skin reactions or allergic rashes
• eye irritation, especially if it gets into the eye
• if the repellent gets into your eyes, immediately flush your eyes with water and contact your doctor or Poison Control Center (1-800-222-1222).
• serious side effects to insect repellents are uncommon if directions are followed.

If you think you are having a bad side effect, discontinue use of the product, wash the affected area with soap and water, and call 911 or contact a Poison Control Center (National Poison Control Center 1-800-222-1222, 24 hours a day, everyday).

Be sure to take the insect repellent bottle with listed ingredients to any doctor, clinic or emergency room you may visit.

Can I use DEET and a sunscreen at the same time?

Yes, sunscreens and insect repellents with DEET can both be applied, but apply the sunscreen first, followed by the insect repellent containing DEET. 

• In general, the recommendation is to use separate products when you apply a sunscreen and any insect repellent at the same time.
• First, apply the sunscreen and then apply the insect repellent.
• Follow the applications directions and frequency for each individual product, which means they may be applied at different times. 

Some insect repellents are available with a sunscreen in the mixture already, but these products are no longer recommended by the CDC. Reapplying the combination sunscreen-repellent product too frequently may lead to repellent side effects.

Limited data have shown that use of DEET with sunscreens may lower the effectiveness of the sunscreen or sun protection factor (SPF) by up to one-third. Due to the decrease in SPF when using a DEET-containing insect repellent after applying sunscreen, you may need to reapply the sunscreen more frequently. 

Are insect repellents safe for children?

The label that is on the container of the insect repellent must state the age limits for children; if no age limits are noted then the repellent can be used in any age range. According to the CDC, most repellents can be used on children aged >2 months, but Oil of Lemon Eucalyptus should NOT be used on children under 3 years.

No serious illness has been linked to the use of DEET in children when used as directed. DEET is the only repellent with recommendations for children from The American Academy of Pediatrics (AAP).

The AAP states “insect repellents containing DEET with a concentration of 10% appear to be as safe as products with a concentration of 30% when used according to the directions on the product labels.” The AAP recommends that repellents should contain no more than 30% DEET when used on children, but no insect repellents should be used on infants less than 2 months of age.

Parents should choose a repellent based on the amount of outdoor time, exposure to mosquitoes, and risk of mosquito-transmitted disease in the area.

Follow these guidelines when applying insect repellent to children:

• apply to your own hands then rub onto the child; do not allow a child to apply it themselves
• avoid a child’s eyes, mouth, and use sparingly around ears
• do not apply repellent to areas with open wounds
• do not apply repellent under clothing; wash treated clothing before wearing again
• wash the treated skin with soap and water when you have returned indoors
• keep repellents out of reach of children and pets.

Other ways to avoid mosquito bites

• wear long sleeves and long pants
• use mosquito netting over bed or seating areas. Protect infants 2 months or younger from mosquitoes by using mosquito netting with an elastic edge for a tight fit for a crib or infant carrier.
• applying permethrin to clothing and bedding (not skin)
• use mosquito nets when camping
• avoid areas of standing water.

Are insect repellents safe in pregnancy?

According to the CDC, there are no additional precautions for pregnant or breastfeeding women; the standard safety tips and directions for use should be followed. As always, if you have questions or concerns, contact your healthcare provider.

A study from Harvard looking at DEET use as a protectant from Zika virus found that it is safe with few side effects if used properly. Several expert researchers also agree.

Insect repellent use in areas with mosquitos carrying the Zika virus is critical. Zika infection during pregnancy can put babies at risk for death and birth defects including small brains (microcephaly), poor growth, and hearing or eyesight loss. The American College of Obstetrics and Gynecology (ACOG) states that DEET, picaridin, IR3535, oil of lemon eucalyptus, paramenthane-diol, or 2-undecanone are all safe for use in pregnancy and while breastfeeding. 

Other measures for Zika protection generally include covering arms and legs, using window screens and bed nets, staying in air conditioned areas as much as possible, and avoiding geographic areas where Zika is prevalent. To learn more about Zika virus, visit the CDC website for the latest information.

Conclusion: Which bug spray is the best?

Healthcare providers typically recommend DEET at a strength of 10% to 35% for most people. It has proven effectiveness and can be used safely in pregnancy and children older than two months of age. Picaridin (KBR 3023) 20% is an reasonable option for people who don't like the sticky feel of DEET or are worried about clothing and gear, but it may not last quite as long.

For higher risk situations, a combination of permethrin-treated clothing and gear, plus DEET on exposed skin areas may be needed.

In general, devices you wear such as wristbands and patches which may contain DEET, OLE, and citronella are not effective.

The EPA publishes a tool to help consumers determine the best possible choices for skin-applied insect repellents. The tool allows you to specify:

• if you need protection from mosquitoes, ticks or both
• length of protection time
• preferred active ingredient
• and other product-specific information

If you are additional questions about using insect repellents you should contact your healthcare provider for advice. 

Additional Information

If you think you are having side effect on your skin, you have swallowed insect repellent, it has gotten into your eyes, or any other serious effect to insect repellent (bug spray) has occurred, call 911 or contact a Poison Control Center (U.S. National Poison Control Center 1-800-222-1222, 24 hours a day, everyday).

The National Pesticide Information Center (NPIC) can also provide information at 1-800-858-7378 about products and toxicity.

Useful Links

• EPA: Insect Repellents: Use and Effectiveness
• CDC: Protection against Mosquitoes, Ticks, & Other Arthropods
• CDC: FAQ: Insect Repellent Use and Safety

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer