Repellants

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Repellents are an important tool to assist people in protecting themselves from mosquito-borne diseases.

CDC recommends the use of products containing active ingredients which have been registered by the U.S. Environmental Protection Agency (EPA) for use as repellents applied to skin and clothing. EPA registration of repellent active ingredients indicates the materials have been reviewed and approved for efficacy and human safety when applied according to the instructions on the label.

Repellents for use on skin and clothing:

CDC evaluation of information contained in peer-reviewed scientific literature and data available from EPA has identified several EPA registered products that provide repellent activity sufficient to help people avoid the bites of disease carrying mosquitoes. Products containing these active ingredients typically provide reasonably long-lasting protection:

• DEET (Chemical Name: N,N-diethyl-m-toluamide or N,N-diethly-3-methyl-benzamide)
• Picaridin (KBR 3023, Chemical Name: 2-(2-hydroxyethyl)-1-piperidinecarboxylic acid 1-methylpropyl ester )
• Oil of Lemon Eucalyptus* or PMD (Chemical Name: para-Menthane-3,8-diol)the synthesized version of oil of lemon eucalyptus
• IR3535 (Chemical Name: 3-[N-Butyl-N-acetyl]-aminopropionic acid, ethyl ester)

EPA characterizes the active ingredients DEET and Picaridin as "conventional repellents" and Oil of Lemon Eucalyptus, PMD, and IR3535 as "biopesticide repellents", which are derived from natural materials. For more information on repellent active ingredients see http://www.epa.gov/pesticides/health/mosquitoes/ai_insectrp.htm.

Published data indicate that repellent efficacy and duration of protection vary considerably among products and among mosquito species and are markedly affected by ambient temperature, amount of perspiration, exposure to water, abrasive removal, and other factors.

In general, higher concentrations of active ingredient provide a longer duration of protection, regardless of the active ingredient, although concentrations above ~50% do not offer a marked increase in protection time. Products with <10% active ingredient may offer only limited protection, often from 1-2 hours. Products that offer sustained release or controlled release (micro-encapsulated) formulations, even with lower active ingredient concentrations, may provide longer protection times. Regardless of what product you use, if you start to get mosquito bites reapply the repellent according to the label instructions or remove yourself from the area with biting insects if possible.

These recommendations are for domestic use in the United States where EPA-registered products are readily available. See CDC Travelers' Health website for additional recommendations concerning protection from insects when traveling outside the United States.

Repellents for use on clothing:

Certain products containing permethrin are recommended for use on clothing, shoes, bed nets, and camping gear, and are registered with EPA for this use. Permethrin is highly effective as an insecticide and as a repellent. Permethrin-treated clothing repels and kills ticks, mosquitoes, and other arthropods and retains this effect after repeated laundering. The permethrin insecticide should be reapplied following the label instructions. Some commercial products are available pretreated with permethrin.

EPA recommends the following precautions when using insect repellents:

• Apply repellents only to exposed skin and/or clothing (as directed on the product label.) Do not use repellents under clothing.
• Never use repellents over cuts, wounds or irritated skin.
• Do not apply to eyes or mouth, and apply sparingly around ears. When using sprays, do not spray directly on facespray on hands first and then apply to face.
• Do not allow children to handle the product. When using on children, apply to your own hands first and then put it on the child. You may not want to apply to childrens hands.
• Use just enough repellent to cover exposed skin and/or clothing. Heavy application and saturation are generally unnecessary for effectiveness. If biting insects do not respond to a thin film of repellent, then apply a bit more.
• After returning indoors, wash treated skin with soap and water or bathe. This is particularly important when repellents are used repeatedly in a day or on consecutive days. Also, wash treated clothing before wearing it again. (This precaution may vary with different repellentscheck the product label.)
• If you or your child should get a rash or other bad reaction from an insect repellent, stop using the repellent, wash the repellent off with mild soap and water, and call a local poison control center for further guidance. If you go to a doctor because of the repellent, take the repellent with you to show the doctor.

Note that the label for products containing oil of lemon eucalyptus specifies that they should not to be used on children under the age of three years. Other than those listed above, EPA does not recommend any additional precautions for using registered repellents on children or on pregnant or lactating women,. For additional information regarding the use of repellent on children, please see CDC's Frequently Asked Questions about Repellent Use. http://www.cdc.gov/ncidod/dvbid/westnile/qa/insect_repellent.htm

DEET-based repellents applied according to label instructions may be used along with a separate sunscreen. No data are available at this time regarding the use of other active repellent ingredients in combination with a sunscreen.

See http://cfpub.epa.gov/oppref/insect/ for additional information on using EPA-registered repellents.

* Note: This recommendation refers to EPA-registered repellent products containing the active ingredient oil of lemon eucalyptus (or PMD). "Pure" oil of lemon eucalyptus (e.g. essential oil) has not received similar, validated testing for safety and efficacy, is not registered with EPA as an insect repellent, and is not covered by this CDC recommendation.

References:

• Barnard DR, Xue RD. Laboratory evaluation of mosquito repellents against Aedes albopictus, Culex nigripalpus, and Ochlerotatus triseriatus (Diptera: Culicidae). J Med Entomol. 2004;41(4):726-30.
• Barnard DR, et al. Repellency of IR3535, KBR3023, para-menthane-3,8-diol, and DEET to Black Salt March mosquitoes (Diptera: Culicidae) in the Everglades National Park. J Med Entomol. 2002; 39(6): 895-899
• Fradin MS, Day JF. Comparative efficacy of insect repellents against mosquito bites. N Engl J Med. 2002; 347(1):13-8.
• Thavara U et al. Laboratory and field evaluations of the insect repellents 3535 (ethyl butyletylaminopropionate) and DEET against mosquito vectors in Thailiand. J of Am Mosq Cont Assoc. 2001, 17(3):190-195