My grandchildren treated their had lice problem with over the counter meds twice. But they weren't sure that the lice were gone. So, on the advice of friends, they bought this Ughbug Bed Bug detector which has uv light and a magnifier. They darkened the room and, sure enough, found several nits still attached to the hair shafts. Using that detector, they were easily able to pick off the nits. No more lice.