July 15, 2007
Insect Repellents — The Facts
by Keisha Green, Pharm.D Candidate, Medical University of South Carolina
Bzzzzz-bzzzzz, what’s that sound? It must be the sound of mosquitoes flying around! But do not be afraid, here is some information about insect repellents to save the day!
Choosing and using insect repellents can be easy if you know the facts. It is important to choose a repellent that has active ingredients registered with the U.S. Environmental Protection Agency (EPA). The active ingredients that are registered with EPA mean that they are approved for effectiveness and safety when used according to the instructions on the label.
There are two active ingredients that have a high level of effectiveness and provide longer-lasting protection than others. They are:
- DEET (N, N-diethyl-m-toluamide)
- Picaridin (KBR 3023)
Also, certain products, which contain permethrin, are recommended for use on clothing, shoes, bed nets, and camping gear, and are registered with EPA for this use.
How long an insect repellent lasts depends on the amount of active ingredient, temperature, amount of physical activity and sweating, and any water exposure. The more active ingredient a product has the longer it provides protection from mosquito bites. For example:
- A product containing 23.8% DEET provides an average of 5 hours of protection from mosquito bites
- A product containing 20% DEET provides almost 4 hours of protection
- A product with 6.65% DEET provides almost 2 hours of protection
- A product with 4.75% DEET provides almost 1hour and a half of protection
How to Use Insect Repellents Safely
- Apply only to exposed skin and/or clothing (as directed on the product label). Do not use 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 face—spray 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 children’s hands. DEET is not recommended for use on children under 2 months of age.
- 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 very important when repellents are used repeatedly in a day or on consecutive days. Also, wash treated clothing before wearing it again.
- If you or your child gets a rash or other bad reaction from an insect repellent, stop using it, wash the repellent off with mild soap and water, and see your doctor. When you go to see the doctor, take the repellent with you.
- If you are going to use sunscreen, apply sunscreen first then the repellent. Do not use products that combine sunscreen and insect repellent because instructions for use are different for each product.
- There are specific products for animals. Be sure to read product labels carefully.