Also Known As: Permethrin, Permethrin Shampoo, Permethrin Lotion, Nix
Permethrin is a common synthetic chemical, widely used as an insecticide, acaricide, and insect repellent. It belongs to the family of synthetic chemicals called pyrethroids and functions as a neurotoxin, affecting neuron membranes by prolonging sodium channel activation. It is not known to rapidly harm most mammals or birds, but is dangerously toxic to cats and fish. In general, it has a low mammalian toxicity and is poorly absorbed by skin.
In medicine, permethrin is a first-line treatment for scabies; a 5% (w/w) cream is marketed by Johnson & Johnson under the name Lyclear. It is also used in 1% over the counter formulations as a treatment for head lice. In nordic countries it is marketed under trade name Nix, often available over the counter.
Permethrin is used on humans to eradicate parasites such as head lice and mites responsible for scabies; the common prescription is Permethrin with 5% concentration for scabies, and OTC (over-the-counter) treatment for head lice/crabs is usually permethrin with 1% concentration. However, the British National Formulary states that permethrin has low efficacy in eradicating head lice.