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Insect Repellents - Topic Overview

You can lower your chance of being bitten by an insect or spiderlike animal (arachnid) by using insect repellents. Mosquitoes, biting flies, and ticks can cause annoying bites and sometimes a serious disease. Mosquito bites can spread infections such as West Nile virus, a virus that causes swelling of the brain (encephalitis), and malaria in some parts of the world. Tick bites can cause serious diseases such as Lyme disease and Rocky Mountain spotted fever. Bites from biting flies are painful and may cause a skin infection.

You can buy many different kinds of insect repellents. Some work better than others. DEET provides the longest-lasting protection against mosquito bites.1

If you have a question or concern about the use of insect repellents, or if you are pregnant or nursing, talk with your doctor.

Products that work the best

DEET (N,N-diethyl-3-meta-toluamide) is the most effective insect repellent.

  • A solution of 23.8% DEET provides about 5 hours of protection from mosquitoes.1 DEET is available in varying strengths up to 100%. Research shows that strengths greater than 50% do not provide substantially higher protection. Unless you are in areas with a large number of mosquitoes, repellents with 10% to 24% DEET should keep most mosquitoes away from your skin.
  • Concerns have been raised about safety, because DEET is applied to the skin. Studies over the past 40 years haven't shown that DEET causes cancer or other illnesses.
  • Experts disagree about the safest concentration of DEET to use on children. No serious illness has been linked to the use of DEET in children when used according to the product recommendations. The American Academy of Pediatrics (AAP) and other experts suggest that it is safe to apply DEET in concentrations of 10% to 30% DEET to children older than age 2 months. When applying DEET to children 2 months to 24 months of age:
    • Use only when there is a high risk of insect bites.
    • Use repellents with the lowest concentration of DEET available (usually 10% to 30%).
    • As with all insect repellents, use DEET sparingly, and never apply to the hands or near the eyes.
    • Apply no more than 1 time a day, and avoid prolonged use.
  • When applying DEET to children 2 years to 12 years of age:
    • Use repellents with the lowest concentration of DEET available (10% to 30%).
    • Apply no more than 3 times a day, and avoid prolonged use.
  • If you are pregnant or breast-feeding and have concerns about the use of DEET, talk with your doctor. There is no evidence that the use of DEET by pregnant or lactating women poses a health hazard to developing babies or children who are breast-feeding.
  • Do not use DEET products that are combined with sunscreen. Sunscreen needs to be applied more often than DEET.
  • DEET reduces how well sunscreen works by one-third.2 If you need to use sunscreen and DEET at the same time, put on sunscreen first and wait 20 minutes before applying DEET. Do not use DEET on skin that will be covered by clothing.
  • DEET should also be used carefully on clothing. DEET may damage some synthetic fabrics as well as plastic watch crystals and eyeglass frames.
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WebMD Medical Reference from Healthwise

Last Updated: August 20, 2012
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
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