Repellent Information

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• What can be done to prevent West Nile virus?

  ››It is important to protect yourself from mosquitoes between dusk and dawn:
  

  • Use mosquito repellent with DEET on exposed skin and clothing when outside between dusk and dawn.
    • For adults, use repellents containing up to 35% DEET (Concentrations higher than 50% do not provide additional protection.)
    • Children between 2 months and 12 years can use repellents containing between 10-30% DEET (always follow product label directions). Do not put DEET on children's hands or feet.
    • Consider wearing long pants and long-sleeved shirts for additional protection.
  • Use mosquito netting or a screened tent when sleeping outdoors and to protect small infants at any time.

• Why should I use a mosquito repellent that contains DEET?

  ››DEET is the most effective insect repellent available. The more DEET an insect repellent contains, the longer it will protect you. A higher percentage of DEET does not mean it will protect you better, just that it will last longer. However, DEET concentrations higher than 50% do not increase the length of protection.
• Is DEET safe?

  ››Yes, products containing DEET are very safe when used according to the directions.
  Always follow these steps:

  • Use enough repellent to cover exposed skin or clothing. Don't apply repellent to skin that is under clothing. Heavy application is not necessary to achieve protection.
  • Do not apply repellent to cuts, wounds, or irritated skin.
  • After returning indoors, wash treated skin with soap and water.
  
  • Do not spray aerosol or pump products in enclosed areas.
  • Do not apply aerosol or pump products directly to your face.
  • Spray your hands and then rub them carefully over the face, avoiding eyes and mouth.

  
  See http://npic.orst.edu/factsheets/DEETgen.pdf for more information.
  
• Can I use an insect repellent containing DEET and sunscreen at the same time?

  ››Yes. People can and should use both sunscreen and DEET when they are outdoors to protect their health. Follow the instructions on the package for proper application of each product. Apply sunscreen first, followed by repellent containing DEET.
  
  

  Wearing clothing with long sleeves and long pants will provide additional protection. You can also apply insect repellent containing DEET to your clothing, rather than directly to your skin.
• What time of day should I wear mosquito repellent?

  ›› Many of the mosquitoes that carry the West Nile virus are especially likely to bite around dusk and dawn. If you are outdoors around these times of the day, it is important to apply repellent. In many parts of the country, there are mosquitoes that also bite during the day, and these mosquitoes have also been found to carry the West Nile virus. The safest decision is to apply repellent whenever you are outdoors.
• How often should repellent be reapplied?

  ››Follow the directions on the product you are using in order to determine how frequently you need to reapply repellent. Sweating or getting wet may mean that you need to re-apply repellent more frequently. If you are not being bitten, it is not necessary to re-apply repellent. Repellents containing a higher concentration of active ingredient (such as DEET) provide longer-lasting protection.
• Should I wear repellent while I am indoors?

  ››Probably not. If mosquitoes are biting you while you are indoors, there are probably better ways to prevent these bites instead of wearing repellent all the time. Check window and door screens for holes that may be allowing mosquitoes inside. If your house or apartment does not have screens, a quick solution may be to staple or tack screening (available from a hardware store) across the windows. In some areas community programs can help older citizens or others who need assistance.
• How does mosquito repellent work?

  ›› Female mosquitoes bite people and animals because they need the protein found in blood to help develop their eggs. Mosquitoes are attracted to people by skin odors and carbon dioxide from breath. Many repellents contain a chemical, N,N-diethyl-m-toluamide (DEET), which repels the mosquito, making the person unattractive for feeding. DEET does not kill mosquitoes; it just makes them unable to locate us. Repellents are effective only at short distances from the treated surface, so you may still see mosquitoes flying nearby. As long as you are not getting bitten, there is no reason to apply more DEET.
• How does the percentage of DEET in a product relate to the amount of protection it gives?

  ››Based on a recent study (Fradin MS, Day JF.Comparative efficacy of insect repellents against mosquito bites. N Engl J Med. 2002;347(1):13-8):

  • A product containing 23.8% DEET provided about 5 hours of protection from mosquito bites.
  • A product containing 20% DEET provided about 4 hours of protection
  • A product with 6.65% DEET provided about 2 hours of protection
  • Products with 4.75% DEET and 2% soybean oil were both able to provide about 1 and a half hours of protection.
  
  
  

  Choose a repellent that provides protection for the amount of time that you will be outdoors. A higher percentage of DEET should be used if you will be outdoors for several hours while a lower percentage of DEET can be used if time outdoors will be limited. You can also re-apply a product if you are outdoors for a longer time than expected and start to be bitten by mosquitoes.
• Are non-DEET repellents effective (e.g. Skin-So-Soft, plant-based repellents?

  ››Some non-DEET repellent products, which are intended to be applied directly to skin, also provide some protection from mosquito bites. However, studies have suggested that other products do not offer the same level of protection, or that protection does not last as long as products containing DEET. A soybean-oil-based product has been shown to provide protection for a period of time similar to a product with a low concentration of DEET (4.75%) (Fradin and Day, 2002.).
  
  

  People should choose a repellent that they will be likely to use consistently and that will provide sufficient protection for the amount of time that they will be spending outdoors. Product labels often indicate the length of time that protection that can be expected from a product. Persons who are concerned about using DEET may wish to consult their health care provider for advice. The National Pesticide Information Center (NPIC) can also provide information through a toll-free number, 1-800-858-7378 or http://npic.orst.edu/
• Should pregnant or nursing women use DEET?

  ›› Women who are pregnant or nursing can use DEET. Be sure to follow the directions carefully.