You shouldn't treat head lice with permethrin
Permethrin is a common head lice treatment. However, recent research is raising concerns about the long-term effects of these pesticides.
Feb 21, 2026 · 4 min read
TL;DR
Permethrin is an insecticide once widely used for head lice. Growing resistance and concerns about long-term effects mean it's no longer the first choice. Silicone- or oil-based treatments and wet combing are safer and often more effective.
What is permethrin?
Permethrin is a synthetic insecticide that kills lice by affecting their nervous system. It was the standard treatment for decades, but many head lice populations have developed resistance, so it often fails to work.
Why avoid permethrin for head lice?
Research shows that permethrin-resistant lice are common. Repeated use can also expose users to pesticides without benefit. Health bodies increasingly recommend non-insecticide options: silicone-based lotions, wet combing, or professional removal.
For sensitive skin or children, choose pesticide-free treatments. Find a clinic near you for expert help.