You should follow the directions for the specific product you are using in order to determine how often to reapply. Sweating or getting wet may mean that you need to reapply more frequently.
In general, the more active ingredient (higher percentage) a mosquito repellent has, the longer a repellent will protect you from mosquitoes. For example, DEET products are available in many formulations -- a product with 30 percent DEET will protect you longer than one with 5 percent DEET.
Here are some general tips on applying mosquito repellent:
- For many hours outside (over three to four hours) or where biting is intense, look for a repellent containing more than 20 percent DEET. Mosquito repellents with more than 50 percent DEET do not offer additional protection.
- For shorter periods of time, use repellents containing less than 20 percent DEET. Other products are also available.
Use your common sense. Reapply mosquito repellent if you start to get bitten, and follow the label instructions.
There are some general considerations for using mosquito repellent safely. Some of these considerations include:
- Always follow the instructions on the product label.
- Apply mosquito repellent only to exposed skin and clothing, as directed on the product label. Do not use repellents under clothing.
- Never apply repellent to cuts, wounds, or irritated skin.
- Never apply to the eyes or mouth, and apply sparingly around ears. When using sprays, do not spray directly on the face -- spray the mosquito repellent on your hands first and then apply to the face.
- Do not allow children to handle mosquito repellent. 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.
- Use just enough mosquito repellent to cover exposed skin and clothing. Heavy application and saturation are generally unnecessary for effectiveness. If biting insects do not respond to a thin film of repellent, apply a bit more.
- After returning indoors, wash treated skin with soap and water, or take a bath. This is particularly important when mosquito 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 repellents -- check the product label.)
- Discontinue use of the mosquito repellent if you or your child gets a rash or other bad reaction. Then, 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 products containing oil of lemon eucalyptus should not be used on children under three years of age.
The EPA does not recommend any other precautions for using registered mosquito repellents on pregnant or breastfeeding women, or on children.
DEET-based mosquito repellents applied according to label instructions may be used along with a separate sunscreen. No data is available at this time regarding the use of other active mosquito repellent ingredients in combination with a sunscreen.