See your doctor for a spinosad prescription
Many prescription lotions contain spinosad, an insecticide derived from bacteria present in the soil. This chemical was approved in 2012 for little kids as well as older. In two clinical trials, 86.7% and 84.6% of patients were lice-free after 14 days of treatment, in contrast to 42.9% and 44.9% with permethrin.
Coat the scalp and apply the liquid on dry hair from roots to tip. Leave it for 10 minutes, wash out and comb for nits. The most common side effects are skin and eye irritation.