According to an article from August 2012 Family Circle magazine, DEET-based insect repellent is safe for kids. As long as you follow some simple guidelines, "Buy a concentration that's less than 30%, says James R. Roberts, M.D., coauthor of the EPA's Recognition and Management of Pesticide Poisoning report. A higher dose increases the chance of side effects. "For most one-to-two-hour outings, 10% is going to be sufficient."
Avoid over-applying the spray, once daily should be enough, and never spritz on eyes. hands or skin that will be covered. Also, imperative: Make sure children shower off repellent before bed. Parents wanting a more natural approach for kids (safe for those older than 3) should purchase a repellent containing lemon eucalyptus oil.