Prescription shampoos are formulated from harsh chemicals that are not guaranteed to kill or eliminate the lice—and exposing your child to these toxins isn’t worth it. Over time and with the use of pesticides, head lice have become resistant to these products. Though they contain strong chemicals, these chemicals are unable to penetrate the nits' eggshell. Once these eggs hatch, you have a new infestation. Choose a safer, more effective treatment that is actually guaranteed to work.