DEET is available in many bug spray products, in concentrations ranging from less than 10 percent to more than 75 percent. The effectiveness of DEET plateaus at approximately 30 percent, but higher concentrations provide longer durations of protection. Products with concentrations around 10 percent are effective for periods of approximately two hours; a concentration of about 24 percent provides an average of five hours of protection. Protection is shortened by swimming, washing, rainfall, sweating, and wiping skin.
A good approach is to select the lowest concentration effective for the amount of time spent outdoors. Products with 10 to 35 percent DEET are adequate in most circumstances. Higher concentrations should be reserved for situations in which insect infestation is high, elevated temperatures and humidity may limit evaporation, or time outdoors will exceed three to four hours.
The American Academy of Pediatrics (AAP) recommends children younger than two months of age should not use products with DEET. For older infants and children, repellents with 10 to 30 percent DEET should be safe and effective when used according to the directions on the product labels. DEET can be used on exposed skin, as well as clothing, socks, and shoes, but should not be used on the face, under clothing, on cuts or irritated skin, or on the hands of young children. DEET should be applied only once a day.
Products containing both DEET and sunscreen are not recommended for children because reapplication (as may be necessary for the sunscreen component) will result in an excessive exposure to DEET.
Missy Nicholson, CPNP
