There are 2 kinds of insect repellents: man-made chemicals and plant-based essential oils.
The best-known chemical repellent is DEET—the common name for N,N-diethyl-m-toluamide. DEET is the main ingredient in many insect repellents. Repellents with DEET have been shown to be more effective than other products in preventing mosquito bites in particular. Repellents with DEET are available as sprays and lotions. Check the product label for information about how much DEET the repellent contains. The more DEET a repellent contains, the longer it can protect you from insect bites.
Another man-made product is picaridin. Picaridin is shown to be as effective as DEET in repelling several types of mosquitoes, but does not last as long. The effects wear off after about 1.5 hours.
Plant-based essential oils include citronella, cedar, eucalyptus, and soybean. These repellents will not protect you as long as those that contain DEET or picaridin, so you will need to reapply them more often.
DEET is safe when used according to directions. DEET should not be used on children younger than 2 months of age. If you have a young child, apply the repellent to your hands first, then apply it to your child's skin. If your child is under 2 months old, protect them with mosquito netting.
The Environmental Protection Agency (EPA) does not suggest using any special precautions for using registered repellants on pregnant women or on women who are breastfeeding. Contact your doctor if you have any concerns about using products that contain DEET. Visit the Centers for Disease Control and Prevention (CDC) website for more information about the safety of insect repellents.
In rare cases, repellents with DEET may cause skin reactions. However, most of these cases have happened when the product was not used according to the directions, such as applying over broken skin, and using over many days without washing in between.
If you think you have a reaction to a DEET product, wash the treated skin and contact your local poison control center.
Although DEET is effective, it is still a chemical-based product. When using products with DEET:
Most plant-based insect repellents use essential oils from one or more of these plants: citronella, cedar, eucalyptus, peppermint, lemongrass, geranium, and soybean. Of the products tested in a small study, a soybean oil-based repellent gave protection from mosquito bites for about 1.5 hours. This is similar to a product with 10% DEET.
Use a soybean oil-based product instead of DEET if you:
When using soybean oil-based repellent, reapply the product if you are outdoors for longer than 1.5 hours, or if you start being bitten by mosquitoes.
Picaridin is a product widely used in Europe and Australia. Its effectiveness is comparable to DEET, but does not last as long and will need to reapplied. It is odorless and does not irritate skin. It is also effective against other insects like fleas or ticks.
Centers for Disease Control and Prevention
US Environmental Protection Agency
The College of Family Physicians of Canada
Public Health Agency of Canada
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6/17/2013 DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed: Insect repellents. American Academy of Pediatrics Healthy Children website. Available at: http://www.healthychildren.org/English/safety-prevention/at-play/pages/Insect-Repellents.aspx?n. Updated March 1, 2017. Accessed May 4, 2017.
Last reviewed May 2017 by Michael Woods, MD, FAAP
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.