Is it OK to use DEET to prevent mosquito bites?

DEET, the active ingredient in many common insect repellents, is generally safe as long as you follow the manufacturer's instructions. DEET provides effective protection against mosquito- and tick-transmitted diseases, such as West Nile virus and Lyme disease. The benefits of avoiding these illnesses generally exceed the risks of the small amount of DEET that might enter your bloodstream through your skin. To stay on the safe side, minimize your time outdoors, especially during the first trimester, and use the lowest con­centration of DEET needed for the amount of time you'll spend outside.