Does hair dye kill lice?

Hair dye does not effectively kill lice. While certain chemicals found in some hair dyes, such as ammonia, hydrogen peroxide, and paraphenylenediamine (PPD), could potentially impact or even kill live lice, they do not penetrate the hardened shell of lice eggs (nits). Since nits remain unaffected, using hair dye as a sole treatment method does not eliminate the entire lice life cycle, leading to persistent infestations when the remaining nits hatch. Additionally, hair dyes are not designed for or tested specifically for their effectiveness against lice, and lice have developed resistance to many over-the-counter medicated treatments. Safer and more effective treatments for head lice include FDA-cleared medical devices, specialized home treatment kits, and manual removal using a fine-toothed comb.