Question: are lice immune to nix?
Answer: Treatment-Resistant Head Lice The new report was last updated in 2002, and since that time, there has been a growing concern that lice are becoming resistant to some common over-the-counter treatments such as permethrins (like Nix) and pyrethrins (like A-200, Clear Lice System, Pronto, R & C, and Rid).